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Network Working Group                                          D. MittonRequest for Comments: 3127                               Nortel NetworksCategory: Informational                                      M. St.Johns                                                  Rainmaker Technologies                                                              S. Barkley                                                                   UUNET                                                               D. Nelson                                                      Enterasys Networks                                                                B. Patil                                                                   Nokia                                                              M. Stevens                                                       Ellacoya Networks                                                                B. Wolff                                                            Databus Inc.                                                               June 2001Authentication, Authorization, and Accounting:Protocol EvaluationStatus of this Memo   This memo provides information for the Internet community.  It does   not specify an Internet standard of any kind.  Distribution of this   memo is unlimited.Copyright Notice   Copyright (C) The Internet Society (2001).  All Rights Reserved.Abstract   This memo represents the process and findings of the Authentication,   Authorization, and Accounting Working Group (AAA WG) panel evaluating   protocols proposed against the AAA Network Access Requirements,RFC2989.  Due to time constraints of this report, this document is not   as fully polished as it might have been desired.  But it remains   mostly in this state to document the results as presented.Mitton, et al.               Informational                      [Page 1]

RFC 3127            AAA Protocol Evaluation Process            June 2001Table of Contents1.  Process Description  . . . . . . . . . . . . . . . . . . . . . .31.1  WG Co-Chair's Note  . . . . . . . . . . . . . . . . . . . . . .31.2  Chairman's Note . . . . . . . . . . . . . . . . . . . . . . . .41.3  Members Statements  . . . . . . . . . . . . . . . . . . . . . .41.4  Requirements Validation Process . . . . . . . . . . . . . . . .61.5  Proposal Evaluation . . . . . . . . . . . . . . . . . . . . . .71.6  Final Recommendations Process . . . . . . . . . . . . . . . . .72.  Protocol Proposals . . . . . . . . . . . . . . . . . . . . . . .83.  Item Level Compliance Evaluation  . . . . . . . . . . . . . . .83.1  General Requirements . . . . . . . . . . . . . . . . . . . . .93.2  Authentication Requirements. . . . . . . . . . . . . . . . . .113.3  Authorization Requirements . . . . . . . . . . . . . . . . . .123.4  Accounting Requirements  . . . . . . . . . . . . . . . . . . .123.5  MOBILE IP Requirements . . . . . . . . . . . . . . . . . . . .134.  Protocol Evaluation Summaries . . . . . . . . . . . . . . . . .144.1  SNMP . . . . . . . . . . . . . . . . . . . . . . . . . . . . .144.2  Radius++ . . . . . . . . . . . . . . . . . . . . . . . . . . .144.3  Diameter . . . . . . . . . . . . . . . . . . . . . . . . . . .144.4  COPS . . . . . . . . . . . . . . . . . . . . . . . . . . . . .144.5  Summary Recommendation   . . . . . . . . . . . . . . . . . . .145.  Security Considerations . . . . . . . . . . . . . . . . . . . .146.  References  . . . . . . . . . . . . . . . . . . . . . . . . . .157.  Authors' Addresses. . . . . . . . . . . . . . . . . . . . . . .15A.Appendix A - Summary Evaluations  . . . . . . . . . . . . . . .17B.Appendix B - Review of the Requirements . . . . . . . . . . . .18B.1 General Requirements. . . . . . . . . . . . . . . . . . . . . .18B.2 Authentication Requirements . . . . . . . . . . . . . . . . . .19B.3 Authorization Requirements. . . . . . . . . . . . . . . . . . .19B.4 Accounting Requirements . . . . . . . . . . . . . . . . . . . .20C.Appendix C - Position Briefs  . . . . . . . . . . . . . . . . .21C.1  SNMP PRO Evaluation  . . . . . . . . . . . . . . . . . . . . .21C.2  SNMP CON Evaluation  . . . . . . . . . . . . . . . . . . . . .28C.3  RADIUS+ PRO Evaluation . . . . . . . . . . . . . . . . . . . .33C.4  RADIUS+ CON Evaluation . . . . . . . . . . . . . . . . . . . .37C.5  Diameter PRO Evaluation  . . . . . . . . . . . . . . . . . . .44C.6  Diameter CON Evaluation  . . . . . . . . . . . . . . . . . . .50C.7  COPS PRO Evaluation  . . . . . . . . . . . . . . . . . . . . .55C.8  COPS CON Evaluation  . . . . . . . . . . . . . . . . . . . . .59D.Appendix D - Meeting Notes  . . . . . . . . . . . . . . . . . .66D.1  Minutes of 22-Jun-2000 Teleconference  . . . . . . . . . . . .66D.2  Minutes of 27-Jun-2000 Teleconference  . . . . . . . . . . . .68D.3  Minutes of 29-Jun-2000 Teleconference  . . . . . . . . . . . .73D.4  Minutes of 06-Jul-2000 Teleconference  . . . . . . . . . . . .78D.5  Minutes of 11-Jul-2000 Teleconference  . . . . . . . . . . . .80   Full Copyright Statement  . . . . . . . . . . . . . . . . . . . . .84Mitton, et al.               Informational                      [Page 2]

RFC 3127            AAA Protocol Evaluation Process            June 20011.  Process Description   Due to time constraints, the original draft of this document was   rushed to meet the publication deadline of the June 2000 Pittsburgh   meeting.  Since the meeting has passed, we do not wish to   substantially revise the findings within this document, so that we   don't give the appearance of changing information after the   presentation.  Only additional descriptions of the process,   formatting, layout editing and errors of fact have been corrected in   subsequent revisions.1.1.  WG Co-Chair's Note:   After the AAA WG re-charter was approved, and the Network Access   Requirements document passed AAA WG Last Call, a Solicitation of   Protocol Submissions was issued on 4/13/2000.  The Solicitation was   sent to the AAA WG mailing list, as well as to other IETF WG mailing   lists related to AAA, including NASREQ, Mobile IP, RAP, and SNMPv3.   Submissions were solicited effective immediately.  Authors of   candidate protocols were requested to notify the AAA WG chairs of   their intent to submit a candidate protocol.  It was suggested that   this notification be sent by May 1, 2000.   Protocol submissions and compliance description documents were to be   submitted in Internet Draft format by email to internet-   drafts@ietf.org.  The deadline for submissions was June 1, 2000.  To   be considered as a candidate, submissions needed to include an   unqualifiedRFC 2026 statement, as described at:http://www.ietf.org/Sec10.txt   In order to assist the AAA WG in evaluating the protocol submissions   and compliance description documents, the AAA WG chairs then formed   an evaluation team, which was announced on May 20, 2000.  The job of   the team was be to put together an Internet Draft documenting their   evaluation of the protocol submissions.  The goal is to have a first   draft available prior to the July 14, 2000 submission deadline for   IETF 48.   In composing the evaluation draft, the evaluation team was asked to   draw from the protocol specifications, the compliance descriptions,   and other relevant documents, the Network Access Requirements   document,RFC 2989.   Mike St. Johns was asked to chair the evaluation team.  The chairs of   WGs related to AAA were also invited to join the team.  These   included Dave Mitton, co-chair of NASREQ WG, Basavaraj Patil, co-   chair of Mobile IP WG, and Mark Stevens, co-chair of the RAP WG.Mitton, et al.               Informational                      [Page 3]

RFC 3127            AAA Protocol Evaluation Process            June 2001   Additional members of the evaluation team were chosen to represent   the interests of network operators as well as developers of AAA   client and server software.   As usual, the IESG advised the evaluation team.  IESG advisors   included Randy Bush and Bert Wijnen, Directors of the Operations and   Management Area.1.2.  Chairman's Note:   This document is the result of 6 weeks of intense work by the panel   listed below.  Our mission was to evaluate the various AAA proposals   and provide recommendations to the AAA working group and to the IESG   on the viability of each of the proposals.   The evaluation process had three distinct phases.  1) Validate the   AAA requirements document [AAAReqts] against the base requirements   documents for NASREQ, MOBILEIP and ROAMOPS.  2) Evaluate each of the   SNMP, Radius++, Diameter and COPS proposal claims against the   validated requirements.  3) Provide final recommendations based on   side by side comparison for each proposal on a requirement by   requirement basis.   In general, the ONLY information the evaluators were allowed to use   throughout the process was that provided in the source documents (the   requirements document and the proposal) or documents referenced by   the source documents.  In other words, if it wasn't written down, it   generally didn't exist.  Our cutoff for acceptance of information was   1 June 2000 - any submissions after that time were not considered in   the panel's deliberations.1.3.  Members Statements   The group was chaired by Michael St.Johns.  David Mitton was the   document editor.  Following are the background statements and any   conflicts of interest from them and the rest of the panel.   Michael St. Johns, Rainmaker Technologies   I have no known conflicts of interest with respect to the AAA   process.  I have neither advocated nor participated in the creation   of any of the submissions.  My company is a service company (ISP) and   will not be involved in the manufacture or sale  of AAA enabled   products.  Other than my participation as the chair of the AAA   evaluation process, I have not had any contact with the AAA standards   process.Mitton, et al.               Informational                      [Page 4]

RFC 3127            AAA Protocol Evaluation Process            June 2001   David Mitton, Nortel Networks   I have been Nasreq WG co-chair and author of several Nasreq drafts.   As well as, previously contributed to several RADIUS drafts.   I have been a RADIUS NAS implementor and Technical Prime on our   Server products, so know it extremely well.  In my current job role I   am involved with Nortel's IP Mobility products, which support   Diameter.   I have written a presentation on COPS vs NASreq Requirements for a   Nasreq meeting, but have not implemented it, nor consider myself an   through expert on the subject.   Stuart Barkley, UUNET   I've been working for 5 years at UUNET on various parts of our dialup   network.  I have extensive experience with designing, developing and   operating our SNMP based usage data gathering system.  I've also been   involved in our radius based authentication and authorization systems   in an advisory position.   I've participated in radius/roamops/nasreq/aaa groups for the past   several years.  I'm not an author or contributer on any of the   requirements or protocol documents being presented although I have   been peripherally involved in these working groups.   Dave Nelson, Enterasys Networks   Very active in the RADIUS WG, especially during the early years.  No   involvement in the AAA submission.  Have not contributed to the   development of Diameter.   No involvement with SNMPv3 or the AAA submission.  David Harrington,   a proponent, works in a different group within my company.  We have   not discussed the submission.  No involvement with the COPS protocol.   Basavaraj Patil, Nokia   I am a contributor to the AAA requirements document (RFC 2977)   submitted by the Mobile IP WG.  I was a member of the team that was   constituted to capture the Mobile IP requirements for AAA services.   As part of the co-chairing activity of the Mobile IP WG I have   realized the need for AAA services by Mobile IP and hence closely   followed the work done in the AAA WG, RADIUS, RoamOps and TR45.6.Mitton, et al.               Informational                      [Page 5]

RFC 3127            AAA Protocol Evaluation Process            June 2001   My present work at Nokia does involve looking at AAA protocols (to   some extent at least) for use in wireless networks.  I have also done   some work with AAA protocols such as Diameter in my previous job at   Nortel Networks.   Mark Stevens, Ellacoya Networks   I am the co-chair of the IETF RAP working group which is the working   group that has developed the COPS protocol.  I have not contributed   to the documents describing how COPS can satisfy AAA requirements.   I participated in early AAA working group meetings, but have not been   an active participant since the group's rechartering.  The company   that currently employees me builds devices might benefit from being   AAA enabled.   Barney Wolff, Databus Inc.   I have implemented RADIUS client, proxy and server software, under   contract to AT&T.  That software is owned by AT&T and I have no   financial interest in it.   I have been a member of the RADIUS WG for several years, and consider   myself an advocate for RADIUS against what I consider unjustified   attacks on it.   I've never worked for any of the companies whose staff have produced   any of the proposals, although I obviously might at some future time.1.4.  Requirements Validation Process   For each of the base requirements documents, the chair assigned a   team member to re-validate the requirement.  The process was fairly   mechanical; the evaluator looked at what was said in [AAAReqts], and   verified that the references and supporting text in the basis   document supported the requirement in [AAAReqts] as stated.  Where   the reference was wrong, too general, missing or otherwise did not   support the requirement, the evaluator either deleted or downgraded   the requirement.  The results of that process were sent to the AAA   mailing list and are also included in this document in the   appendixes.  The group's used [AAAReqts] as modified by our   validation findings to evaluate the AAA proposals.Mitton, et al.               Informational                      [Page 6]

RFC 3127            AAA Protocol Evaluation Process            June 20011.5.  Proposal Evaluation   For each of the four proposals, the chair assigned two panel members   to write evaluation briefs.  One member was assigned to write a 'PRO'   brief and could take the most generous interpretation of the   proposal; he could grant benefit of doubt.  The other member was   assigned to write a 'CON' brief and was required to use the strictest   criteria when doing his evaluation.   Each brief looked at each individual requirement and evaluated how   close the proposal came in meeting that requirement.  Each item was   scored as one of an 'F' for failed to meet the requirement, 'P' for   partially meeting the requirement, or 'T' for totally meeting the   requirement.  The proposals were scored only on the information   presented.  This means that a particular protocol might actually meet   the specifics of a requirement, but if the proposal did not state,   describe or reference how that requirement was met, in might be   scored lower.   The panel met by teleconference to discuss each proposal and the PRO   and CON briefs.  Each of the briefers discussed the high points of   the brief and gave his summary findings for the proposal.  We then   discussed each individual requirement line-by-line as a group.  At   the conclusion, the members provided their own line-by-line   evaluations which were used to determine the consensus evaluation for   the specific requirement relative to that proposal.  The meeting   notes from those teleconferences as well as the individual briefs are   included in the appendixes.1.6.  Final Recommendations Process   The panel met for one last time to compare the results for the four   proposals and to ensure we'd used consistent evaluation criteria.  We   did a requirement by requirement discussion, then a discussion of   each of the protocols.   The final phase was for each member to provide his final summary   evaluation for each of the protocols.  Each proposal was scored as   either Not Acceptable, Acceptable Only For Accounting, Acceptable   with Engineering and Fully Acceptable.  Where a proposal was   acceptable with engineering, the member indicated whether it would be   a small, medium or large amount.   It should be noted that score indicated the opinion of the team   member.  And they may have taken into consideration background   knowledge or additional issues not captured in the minutes presented   here.Mitton, et al.               Informational                      [Page 7]

RFC 3127            AAA Protocol Evaluation Process            June 2001   Each member's scores were used within the group to develop the   group's consensus.2.  Protocol Proposals   The following proposal documents were submitted to the AAA WG for   consideration by the deadline.   - SNMP:      [SNMPComp] "Comparison of SNMPv3 Against AAA Network Access                  Requirements", Work in Progress.   - RADIUS Enhancements:      [RADComp]  "Comparison of RADIUS Against AAA Network Access                  Requirements", Work in Progress.      [RADExt]   "Framework for the extension of the RADIUS(v2)                  protocol", Work in Progress.   - Diameter      [DIAComp]  "Comparison of Diameter Against AAA Network Access                  Requirements", Work in Progress.   - COPS for AAA:      [COPSComp]"Comparison of COPS Against the AAA NA Requirements",                  Work in Progress.      [COPSAAA]"COPS Usage for AAA", Work in Progress.3.  Item Level Compliance Evaluation   For each requirement item, the group reviewed the proposal's level of   compliance.  Where the proposal was lacking, the evaluators may have   made supposition on how hard it would be to resolve the problem.  The   following shows the consensus results for each requirement item.   Key:   T = Total Compliance, Meets all requirements fully   P = Partial Compliance, Meets some requirements   F = Failed Compliance, Does not meet requirements acceptably   Where two are shown eg: P/T, there was a tie.Mitton, et al.               Informational                      [Page 8]

RFC 3127            AAA Protocol Evaluation Process            June 2001   The sub-section numbering corresponds to the requirements document   section and item numbers.  This relative numbering was also used in   the Protocol Position presentations, here in the appendices.3.1 General Requirements   3.1.1 Scalability - SNMP:P, RADIUS:P, Diameter:T, COPS:T   SNMP was downgraded due to a lack of detail of how the current agent   model would be adapted to a client request based transaction.  The   RADIUS proposal did not address the problem adequately.  There are   open issues in all proposals with respect to webs of proxies.   3.1.2 Fail-over - SNMP:P, RADIUS:P, Diameter:P, COPS:T/P   The group particularly noted that it didn't think any protocol did   well in this requirement.  Insufficient work has been done to specify   link failure detection and primary server recovery in most   submissions.  COPS has some mechanisms but not all.  How these   mechanisms would work in a web of proxies has not been addressed.   3.1.3 Mutual Authentication  - SNMP:T, RADIUS:T/P, Diameter:T, COPS:T   Many of the submissions missed the point of the requirement.  There   should be a way for the peers to authenticate each other, end-to-end,   or user-to-server.   However, the group questions who really needs   this feature, and if it could be done at a different level.   Mutual authentication in RADIUS is only between hops.   3.1.4 Transmission Level Security  - SNMP:T, RADIUS:P, Diameter:T,   COPS:T   All protocols have methods of securing the message data.   3.1.5 Data Object Confidentiality  - SNMP:P, RADIUS:P, Diameter:T,   COPS:T   This requirement usually comes from third-party situations, such as   access outsourcing.   Diameter and COPS both use CMS formats to secure data objects.  The   group is concerned if this method and it's support is perhaps too   heavy weight for NAS and some types of edge systems.Mitton, et al.               Informational                      [Page 9]

RFC 3127            AAA Protocol Evaluation Process            June 2001   3.1.6 Data Object Integrity  - SNMP:F, RADIUS:P, Diameter:T, COPS:T   How to guard the data object from changes was not adequately   described in the SNMP proposal.  The RADIUS solution was not very   strong either.   3.1.7 Certificate Transport  - SNMP:T, RADIUS:T, Diameter:T, COPS:T   All protocols can figure out some way to transport a certificate.   3.1.8 Reliable AAA Transport  - SNMP:P, RADIUS:P, Diameter:T, COPS:T   The requirement does not give a definition of "how reliable" it must   be.   The SNMP and RADIUS proposals lacked in providing solutions to   message retransmission and recovery.   3.1.9 Run over IPv4  - SNMP:T, RADIUS:T, Diameter:T, COPS:T   3.1.10 Run over IPv6  - SNMP:P, RADIUS:T, Diameter:T, COPS:T   The SNMP proposal indicated that this area is still in the   experimental stages.   3.1.11 Support Proxy and Routing Brokers  - SNMP:F, RADIUS:P,   Diameter:T, COPS:P   The SNMP proposal did not address this requirement.  COPS claims   support, but does not work through some of the issues.  Diameter was   the only protocol that attempted to address this area to a fair   extent.   3.1.12 Auditability - SNMP:F, RADIUS:F, Diameter:T, COPS:P   We treated this requirement as something like "non-repudiation".   There is a concern that digital signatures may be too computationally   expensive for some equipment, and not well deployed on those   platforms.   The SNMP and RADIUS proposals did not attempt to work this   requirement.  COPS suggests that a History PIB will help solve this   problem but gives no description.Mitton, et al.               Informational                     [Page 10]

RFC 3127            AAA Protocol Evaluation Process            June 2001   3.1.13 Shared Secret Not Required  - SNMP:P/T, RADIUS:T, Diameter:T,   COPS:T   The requirement is interpreted to mean that any application level   security can be turned off in the presence of transport level   security.   Pretty much every protocol can use an enveloping secure transport   that would allow them not to use an internal secret.   3.1.14 Ability to Carry Service Specific Attributes  - SNMP:T,   RADIUS:T, Diameter:T, COPS:T3.2 Authentication Requirements   3.2.1 NAI Support  - SNMP:T, RADIUS:T, Diameter:T, COPS:T   3.2.2 CHAP Support  - SNMP:T, RADIUS:T, Diameter:T, COPS:T   3.2.3 EAP Support  - SNMP:T, RADIUS:T, Diameter:T, COPS:T   3.2.4 PAP/Clear-text Passwords  - SNMP:T, RADIUS:T, Diameter:T,   COPS:T   The requirement for clear-text passwords comes from one-time-password   systems and hard-token (SecurID) systems.   3.2.5 Reauthentication on demand - SNMP:T, RADIUS:P, Diameter:P,   COPS:T   To supply this, the proposal must have asynchronous peer-to-peer   capabilities, and there must defined operation for such state   changes.   We also distinguished event-driven Reauthentication from timer-driven   (or lifetime-driven).  Also concerned about how this would work in a   proxy environment.   3.2.6 Authorization w/o Authentication - SNMP:P, RADIUS:T/P,   Diameter:T, COPS:T   This requirement really means authorization with trivial   authentications (e.g. by assertion or knowledge).Mitton, et al.               Informational                     [Page 11]

RFC 3127            AAA Protocol Evaluation Process            June 20013.3 Authorization Requirements   3.3.1 Static and Dynamic IP Addr Assignment - SNMP:P/F, RADIUS:T,   Diameter:T, COPS:T   There is difficulty in interpreting what is static or dynamic with   respect to the viewpoint of the client, server, administrator or   user.   3.3.2 RADIUS Gateway Capability  - SNMP:P, RADIUS:P, Diameter:T/P,   COPS:P   It was noted that any new capability in a new AAA protocol would not   be able to map directly back to RADIUS.  But this is already a   problem within a RADIUS environment.   3.3.3 Reject Capability  - SNMP:T/P/F, RADIUS:T, Diameter:T, COPS:P   3.3.4 Preclude Layer 2 Tunneling  - SNMP:F, RADIUS:T, Diameter:T,   COPS:T   3.3.5 Reauthorization on Demand  - SNMP:P/F, RADIUS:P, Diameter:T/P,   COPS:T   Some evaluators wondered how the server will know that re-   authorization is supposed to be done?  Will it interface to something   external, or have sufficient internals?   3.3.6 Support for Access Rules & Filters  - SNMP:P, RADIUS:P,   Diameter:P, COPS:T/P   Only the Diameter proposal actually tackled this issue, but the group   felt that the rules as designed were too weak to be useful.  There   was also concern about standardizing syntax without defining   semantics.   3.3.7 State Reconciliation - SNMP:F, RADIUS:P/F, Diameter:P, COPS:T/P   All of the protocols were weak to non-existent on specifying how this   would be done in a web of proxies situation.   3.3.8 Unsolicited Disconnect  - SNMP:T, RADIUS:P, Diameter:T, COPS:T3.4 Accounting Requirements   3.4.1 Real Time Accounting  - SNMP:T, RADIUS:T, Diameter:T, COPS:TMitton, et al.               Informational                     [Page 12]

RFC 3127            AAA Protocol Evaluation Process            June 2001   3.4.2 Mandatory Compact Encoding  - SNMP:T, RADIUS:T, Diameter:T,   COPS:T   3.4.3 Accounting Record Extensibility  - SNMP:T, RADIUS:T,   Diameter:T, COPS:T   3.4.4 Batch Accounting  - SNMP:T, RADIUS:F, Diameter:P, COPS:P   Some members of the group are not sure how this fits into the rest of   the AAA protocol, which is primarily real-time and event driven.   Would this be better met with FTP?   3.4.5 Guaranteed Delivery   - SNMP:T, RADIUS:T, Diameter:T, COPS:T   3.4.6 Accounting Timestamps       - SNMP:T, RADIUS:T, Diameter:T,   COPS:T   3.4.7 Dynamic Accounting  - SNMP:T, RADIUS:T, Diameter:T, COPS:T3.5 MOBILE IP Requirements   3.5.1 Encoding of MOBILE IP Registration Messages  - SNMP:T,   RADIUS:T/P, Diameter:T, COPS:T   3.5.2 Firewall Friendly   - SNMP:F, RADIUS:T, Diameter:P, COPS:P   There was considerable discussion about what it means to be "firewall   friendly".  It was suggested that not making the firewall look into   packets much beyond the application port number.  Protocols such as   SNMP and COPS are at a disadvantage, as you must look far into the   packet to understand the intended operation.  Diameter will have the   disadvantage of SCTP, which is not well deployed or recognized at the   moment.   SNMP and COPS also have the problem that they are used for other   types of operations than just AAA.   Should firewalls have AAA Proxy engines?   We didn't look at "NAT friendly" issues either.   COPS:T   The group is not clear on how this requirement impacts the actual   protocol.  Raj explained it to us, but we mostly took it on faith.Mitton, et al.               Informational                     [Page 13]

RFC 3127            AAA Protocol Evaluation Process            June 20014.  Protocol Evaluation Summaries4.1.  SNMP   SNMP is generally not acceptable as a general AAA protocol.  There   may be some utility in its use for accounting, but the amount of   engineering to turn it into a viable A&A protocol argues against   further consideration.4.2.  Radius++   Radius++ is not considered acceptable as an AAA protocol.  There is a   fairly substantial amount of engineering required to make it meet all   requirements, and that engineering would most likely result in   something close to the functionality of Diameter.4.3.  Diameter   Diameter is considered acceptable as an AAA protocol.  There is some   minor engineering required to bring it into complete compliance with   the requirements but well within short term capabilities.  Diameter   might also benefit from the inclusion of a broader data model ala   COPS.4.4.  COPS   COPS is considered acceptable as an AAA protocol.  There is some   minor to medium engineering required to bring it into complete   compliance with the requirements.4.5.  Summary Recommendation   The panel expresses a slight preference for Diameter based on the   perception that the work for Diameter is further along than for COPS.   However, using SCTP as the transport mechanism for Diameter places   SCTP on the critical path for Diameter.  This may ultimately result   in COPS being a faster approach if SCTP is delayed in any way.5.  Security Considerations   AAA protocols enforce the security of access to the Internet.  The   design of these protocols and this evaluation process took many   security requirements as critical issues for evaluation.  A candidate   protocol must meet the security requirements as documented, and must   be engineered and reviewed properly as developed and deployed.Mitton, et al.               Informational                     [Page 14]

RFC 3127            AAA Protocol Evaluation Process            June 20016.  References   [AAAReqts] Aboba, B., Clahoun, P., Glass, S., Hiller, T., McCann, P.,              Shiino, H., Walsh, P., Zorn, G., Dommety, G., Perkins, C.,              Patil, B., Mitton, D., Manning, S., Beadles, M., Chen, X.,              Sivalingham, S., Hameed, A., Munson, M., Jacobs, S., Lim,              B., Hirschman, B., Hsu, R., Koo, H., Lipford, M.,              Campbell, E., Xu, Y., Baba, S. and E. Jaques, "Criteria              for Evaluating AAA Protocols for Network Access",RFC2989, April 2000.   [AAAComp]  Ekstein, TJoens, Sales and Paridaens, "AAA Protocols:              Comparison between RADIUS, Diameter and COPS", Work in              Progress.   [SNMPComp] Natale, "Comparison of SNMPv3 Against AAA Network Access              Requirements", Work in Progress.   [RADComp]  TJoens and DeVries, "Comparison of RADIUS Against AAA              Network Access Requirements", Work in Progress.   [RADExt]   TJoens, Ekstein and DeVries, "Framework for the extension              of the RADIUS (v2) protocol", Work in Progress,   [DIAComp]  Calhoun, "Comparison of Diameter Against AAA Network              Access Requirements", Work in Progress.   [COPSComp] Khosravi, Durham and Walker, "Comparison of COPS Against              the AAA NA Requirements", Work in Progress.   [COPSAAA]  Durham, Khosravi, Weiss and Filename, "COPS Usage for              AAA", Work in Progress.7.  Authors' Addresses   David Mitton   Nortel Networks   880 Technology Park Drive   Billerica, MA 01821   Phone: 978-288-4570   EMail: dmitton@nortelnetworks.comMitton, et al.               Informational                     [Page 15]

RFC 3127            AAA Protocol Evaluation Process            June 2001   Michael StJohns   Rainmaker Technologies   19050 Pruneridge Ave, Suite 150   Cupertino, CA 95014   Phone: 408-861-9550 x5735   EMail: stjohns@rainmakertechnologies.com   Stuart Barkley   UUNET   F1-1-612   22001 Loudoun County Parkway   Ashburn, VA  20147  US   Phone: 703-886-5645   EMail: stuartb@uu.net   David B. Nelson   Enterasys Networks, Inc. (a Cabletron Systems company)   50 Minuteman Road   Andover, MA 01810-1008   Phone: 978-684-1330   EMail: dnelson@enterasys.com   Basavaraj Patil   Nokia   6000 Connection Dr.   Irving, TX 75039   Phone: +1 972-894-6709   EMail: Basavaraj.Patil@nokia.com   Mark Stevens   Ellacoya Networks   7 Henry Clay Drive   Merrimack, NH  03054   Phone: 603-577-5544 ext. 325   EMail: mstevens@ellacoya.com   Barney Wolff, Pres.   Databus Inc.   15 Victor Drive   Irvington, NY 10533-1919 USA   Phone: 914-591-5677   EMail: barney@databus.comMitton, et al.               Informational                     [Page 16]

RFC 3127            AAA Protocol Evaluation Process            June 2001Appendix A - Summary Evaluations Consensus Results by Requirement             and Protocol   Requirement Section         SNMP      Radius++  Diameter  COPS           1.1.1                P         P         T         T           1.1.2                P         P         P       T/P           1.1.3                T       T/P         T         T           1.1.4                T         P         T         T           1.1.5                P         P         T         T           1.1.6                F         P         T         T           1.1.7                T         T         T         T           1.1.8                P         P         T         T           1.1.9                T         T         T         T           1.1.10               P         T         T         T           1.1.11               F         P         T         P           1.1.12               F         F         T         P           1.1.13             P/T         T         T         T           1.1.14               T         T         T         T           1.2.1                T         T         T         T           1.2.2                T         T         T         T           1.2.3                T         T         T         T           1.2.4                T         T         T         T           1.2.5                T         P         P         T           1.2.6                P       T/P         T         T           1.3.1              P/F         T         T         T           1.3.2                P         T       T/P         P           1.3.3            T/P/F         T         T         P           1.3.4                F         T         T         T           1.3.5              P/F         P       T/P         T           1.3.6                P         P         P       T/P           1.3.7                F       P/F         P       T/P           1.3.8                T         P         T         T           1.4.1                T         T         T         T           1.4.2                T         T         T         T           1.4.3                T         T         T         T           1.4.4                T         F         P         P           1.4.5                T         T         T         T           1.4.6                T         T         T         T           1.4.7                T         T         T         T           1.5.1                T       T/P         T         T           1.5.2                F         T         P         P           1.5.3                F         P         T         TMitton, et al.               Informational                     [Page 17]

RFC 3127            AAA Protocol Evaluation Process            June 2001Appendix B - Review of the Requirements   Comments from the Panel on then work in progress, "Criteria for   Evaluating AAA Protocols for Network Access" now revised and   published asRFC 2989.  This became the group standard interpretation   of the requirements at the time.B.1 General Requirements   Scalability - In clarification [a], delete "and tens of thousands of   simultaneous requests."  This does not appear to be supported by any   of the three base documents.   Transmission level security - [Table] Delete the ROAMOPS "M" and   footnote "6".  This appears to be an over generalization of the   roaming protocol requirement not necessarily applicable to AAA.   Data object confidentiality - [Table] Delete the MOBILE IP "S" and   footnote "33".  The base document text does not appear to support   this requirement.   Reliable AAA transport mechanism - In clarification [h] delete   everything after the "...packet loss" and replace with a ".".  The   requirements listed here are not necessarily supported by the base   document and could be mistakenly taken as requirements for the AAA   protocol in their entirety.   Run over IPv4 - [Table] Replace the MOBILE IP footnote "17" with   footnote "33".  This appears to be a incorrect reference.   Run over IPv6 - [Table] Replace the MOBILE IP footnote "18" with a   footnote pointing tosection 8 of [8].  This appears to be an   incorrect reference.   Auditability - Clarification [j] does not appear to coincide with the   NASREQ meaning of Auditability.  Given that NASREQ is the only   protocol with an auditability requirement, this section should be   aligned with that meaning.   Shared secret not required - [Table] General - This section is   misleadingly labeled.  Our team has chosen to interpret it as   specified in clarification [k] rather than any of the possible   interpretations of "shared secret not required".  We recommend the   tag in the table be replaced with "Dual App and Transport Security   Not Required" or something at least somewhat descriptive of [k].   Delete the NASREQ "S" and footnote "28" as not supported by the   NASREQ document.  Delete the MOBILE IP "O" and footnotes "34" and 39"   as not supported.Mitton, et al.               Informational                     [Page 18]

RFC 3127            AAA Protocol Evaluation Process            June 2001B.2 Authentication Requirements   NAI Support - [Table] Replace MOBILE IP footnote "38" with "39".   This appears to be a more appropriate reference.   CHAP Support - [Table] Delete MOBILE IP "O" as unsupported.   EAP Support - [Table] Delete MOBILE IP "O" as unsupported.   PAP/Clear-Text Support - [Table] Replace NASREQ footnote "10" with   "26" as being more appropriate.  Replace ROAMOPS "B" with "O".  The   reference text appears to not explicitly ban this and specifically   references clear text for OTP applications.  Delete MOBILE IP "O" as   unsupported.   Re-authentication on demand - Clarification [e] appears to go beyond   the requirements in NASREQ and MOBILE IP.  [Table] Delete MOBILE IP   footnote "30" as inapplicable.   Authorization Only without Authentication - Clarification [f] does   not include all NASREQ requirements, specifically that unneeded   credentials MUST NOT be required to be filled in.  Given that there   are no other base requirements (after deleting the MOBILE IP   requirement) we recommend that clarification [f] be brought in line   with NASREQ.  [Table] Delete MOBILE IP "O" and footnote "30".  The   referenced text does not appear to support the requirement.B.3 Authorization Requirements   Static and Dynamic... - Clarification [a] appears to use a   particularly strange definition of static and dynamic addressing.   Recommend clarification here identifying who (e.g. client or server)   thinks address is static/dynamic.  [Table] ROAMOPS "M" appears to be   a derived requirement instead of directly called out.  The footnote   "1" should be changed to "5" as being more appropriate.  A text   clarification should be added to this document identifying the   derived requirement.   RADIUS Gateway capability - [Table] Delete the MOBILE IP "O" and   footnote "30".  The referenced text does not appear to support the   requirement.   Reject capability - [Table] Delete the NASREQ "M" and footnote "12".   The NASREQ document does not appear to require this capability.Mitton, et al.               Informational                     [Page 19]

RFC 3127            AAA Protocol Evaluation Process            June 2001   Reauthorization on Demand - [Table] Delete the MOBILE IP "S" and   footnotes "30,33" The referenced text does not support this   requirement.   Support for Access Rules... - Clarification [e] has a overbroad list   of requirements.  NASREQ only requires 5-8 on the list, and as The   MOBILE IP requirement is not supported by its references, this   clarification should match NASREQ requirements.  [Table] Delete the   MOBILE IP "O" and footnotes "30,37" as not supported.   State Reconciliation - Clarification [f] should be brought in line   with NASREQ requirements.  The clarification imposes overbroad   requirements not required by NASREQ and NASREQ is the only service   with requirements in this area.B.4 Accounting Requirements   Real-Time accounting - [Table] Replace MOBILE IP footnote [39] with a   footnote pointing tosection 3.1 of [3] as being more appropriate.   Mandatory Compact Encoding - [Table] Delete MOBILE IP "M" and   footnote "33" as the reference does not support the requirement.   Accounting Record Extensibility - [Table] Delete NASREQ "M" and   footnote "15" as the reference does not support the requirement.   Accounting Time Stamps - [Table] Delete MOBILE IP "S" and footnote   "30" as they don't support the requirement.  Replace MOBILE IP   footnote "40" with a footnote pointing tosection 3.1 of [3] as being   more appropriate.   Dynamic Accounting - [Table] Replace the NASREQ footnote "18" with a   footnote pointing tosection 8.4.1.5 of [3].  Delete the MOBILE IP   "S" and footnote "30" as the reference does not support the   requirement.   Footnote section.   [40] should be pointing to 6.1 of [4].   [41] should be pointing to 6.2.2 of [4].   [45] should be pointing to 6.4 of [4].   [46] should be pointing to 8 of [4].Mitton, et al.               Informational                     [Page 20]

RFC 3127            AAA Protocol Evaluation Process            June 2001Appendix C - Position BriefsC.1 SNMP PRO Evaluation   Evaluation of SNMP AAA Requirements   PRO Evaluation   Evaluator - Stuart Barkley   Ref [1] is "Comparison of SNMPv3 Against AAA Network Access   Requirements", aka 'the document'   Ref [2] is the aaa eval criteria as modified by us, aka 'the   requirements'   The document uses T to indicate total compliance, P to indicate   partial compliance and F to indicate no compliance.  For each section   I've indicated my grade for the section.  If there is a change, I've   indicated that and the grade given by the authors.   1 Per item discussion   1.1 General Requirements   1.1.1 Scalability - Grade T   The document indicates that SNMP can adequately handle that scale   from the requirements document.  Since most current uses are ppp   connections and SNMP is already capable of handling the interface   table and other per session tables it is clear that basic capacity   exists.  Additions to support other tables and variables scales in a   simple linear fashion with the number of additional variables and   protocol interactions.  Regardless of the final selected protocol   handling the scaling required is not a trivial undertaking.  SNMP can   draw upon existing network management practices to assist in this   implementation.   1.1.2 Fail-over - Grade T   SNMP is of vital importance to the operation of most networks.   Existing infrastructures can handle required failover or other   redundant operations.   1.1.3 Mutual Authentication - Grade T   The use of shared secrets described in the document is a well   understood method of integrity control.  Although shared secrets   don't necessarily provide full authentication since other parties may   also have the same secrets, the level of authentication is sufficient   for the task at hand.  In many cases the SNMP infrastructure willMitton, et al.               Informational                     [Page 21]

RFC 3127            AAA Protocol Evaluation Process            June 2001   already exist and shared secrets should already be properly managed   on an operational network.  A failure of the SNMP shared secret   approach regardless of the AAA protocol will likely leave equipment   and systems open to substantial misuse bypassing any more elaborate   AAA authentication.   1.1.4 Transmission Level Security - Grade T   SNMPv3 provides many additional security options which were not   available or were more controversial in previous SNMP versions.   1.1.5 Data Object Confidentiality - New Grade P (from T)   The document discusses SNMPv3 which can provide data confidentially   for data passing over the wire.  There is substantial implied AAA   architecture (brokers and proxies) in the requirements that full   conformance is difficult to determine.  In particular, the evaluator   has difficulty with the concept of "the target AAA entity for whom   the data is ultimately destined", but will concede that the desired   requirement is only partially met (most especially with the transfer   of a PAP password).   1.1.6 Data Object Integrity - New Grade T (from P)   SNMP has full capabilities that allow the authentication of the data.   Brokers, proxies or other intermediaries in the data chain can verify   the source of the information and determine that the data has not   been tampered with.  The document downgrades the grade to P because   of confusion over the integrity checking role of intermediaries.   1.1.7 Certificate Transport - Grade T   The requirements require the capability of transporting certificates   but do not have any specific use for the certificates.  The   requirements make assumptions that the protocol selected will be   dependent upon certificates, but this is not necessarily true.  SNMP   can transport arbitrary objects and can transport certificates if   necessary.  The document indicates some issues with size of   certificates and current maximum practical data sizes, however if the   compact encoding requirement extends to the internal certificate   information this should be less of an issue.   1.1.8 Reliable AAA Transport - New Grade T (from P)   The requirements is stated rather strongly and makes substantial   assumptions of AAA protocol architecture and based upon current   protocols and their failings.  SNMP allows for great flexibility in   retransmission schemes depending upon the importance of the data.Mitton, et al.               Informational                     [Page 22]

RFC 3127            AAA Protocol Evaluation Process            June 2001   1.1.9 Run over IPv4 - Grade T   SNMP has operated in this mode for many years.   1.1.10 Run over IPv6 - New Grade T (from P)   SNMP must support IPv6 for many other systems so support for this   should be possible by the time the requirement becomes effective.   The document indicates that experimental versions satisfying this   requirement are already in existence.   1.1.11 Support Proxy and Routing Brokers - New Grade T (from P)   The requirements make significant assumptions about the final   architecture.  It is well within the capabilities of SNMP to provide   intermediaries which channel data flows between multiple parties.   The document downgrades SNMPs compliance with this requirement due to   issues which are covered more specifically under "Data Object   Confidentially" which the evaluator has downgraded to P.   1.1.12 Auditability - New Grade T (from F)   Data flows inside SNMP are easily auditable by having secondary data   flows established which provide copies of all information to   auxiliary servers.  The document grades this as a failure, but this   support is only minor additions within a more fully fleshed out set   of data flows.   1.1.13 Shared Secret Not Required - Grade T   Shared secrets are not required by SNMP.  They are desirable in many   instances where a lower level does not provide the necessary   capabilities.  The document supplies pointers to various security   modes available.   1.1.14 Ability to Carry Service Specific Attributes - Grade T   SNMP has long had the ability for other parties to create new   unambiguous attributes.   1.2 Authentication Requirements   1.2.1 NAI Support - Grade T   SNMP easily supports this.  NAIs were defined to be easily carried in   existing protocols.Mitton, et al.               Informational                     [Page 23]

RFC 3127            AAA Protocol Evaluation Process            June 2001   1.2.2 CHAP Support - Grade T   SNMP can easily provide objects to pass the necessary information for   CHAP operation.   1.2.3 EAP Support - New Grade T (from P)   SNMP can easily provide objects to pass the necessary information for   EAP operation.  As with CHAP or PAP MIB objects can be created to   control this operation thus the upgrade from the document grade.   1.2.4 PAP/Clear-text Passwords - New Grade P (from T)   SNMP can easily provide objects to pass the necessary information for   PAP operation.  The requirement about non-disclosure of clear text   passwords make assumptions about the protocol implementation.  The   choice to use clear text passwords is inherently insecure and forced   protocol architecture don't really cover this.  This requirement   grade is downgraded to P (partial) because the document does not   really address the confidentially of the data at application proxies.   1.2.5 Reauthorization on demand - Grade T   SNMP can easily provide objects to control this operation.   1.2.6 Authorization w/o Authentication - New Grade T (from T)   The document makes an incorrect interpretation of this requirement.   However, SNMP makes no restriction which prevents to desired   requirements.  No actual change of grade is necessary, since both the   actual requirements and the incorrect interpretation are satisfied by   SNMP.   1.3 Authorization Requirements   1.3.1 Static and Dynamic IP Addr Assignment - Grade T   SNMP can easily provide objects to control this operation.   1.3.2 RADIUS Gateway Capability - Grade T   As the document describes, with the addition of any necessary   compatibility variables SNMP can be gatewayed to RADIUS applications.Mitton, et al.               Informational                     [Page 24]

RFC 3127            AAA Protocol Evaluation Process            June 2001   1.3.3 Reject Capability - Grade T   Any of the active components in the SNMP based structure could decide   to reject and authentication request for any reason.  Due to mixing   different levels of requirements the document doesn't attempt to   directly address this, instead indicating that a higher level   application can cause this operation.   1.3.4 Preclude Layer 2 Tunneling - New Grade T (from ?)   Nothing in SNMP explicitly interacts with the selection of any   tunneling mechanisms the client may select.  The document author was   unclear about the needs here.   1.3.5 Reauth on Demand - Grade T   SNMP can easily provide objects to control this operation.   1.3.6 Support for ACLs - Grade T   The document indicates that should it be desired SNMP can provide   objects to control these operations.  In addition, active components   can apply substantial further configurable access controls.   1.3.7 State Reconciliation - Grade T   The requirements describe an over broad set of required capabilities.   The document indicates concern over incompatibilities in the   requirements, however SNMP can provide methods to allow active   components to reacquire lost state information.  These capabilities   directly interact with scalability concerns and care needs to be   taken when expecting this requirement to be met at the same time as   the scalability requirements.   1.3.8 Unsolicited Disconnect - Grade T   The document indicates that SNMP can easily provide objects to   control this operation.   1.4 Accounting Requirements   1.4.1 Real Time Accounting - Grade T   SNMP can provide this mode of operation.  The document outlines   methods both fully within SNMP and using SNMP to interface with other   transfer methods.  Many providers already use SNMP for real timeMitton, et al.               Informational                     [Page 25]

RFC 3127            AAA Protocol Evaluation Process            June 2001   notification of other network events.  This capability can directly   interact with scalability concerns and implementation care needs to   be taken to make this properly interact is large scale environments.   1.4.2 Mandatory Compact Encoding - Grade T   The document indicates the possibility of controlling external   protocols to handle data transmissions where the BER encoding of SNMP   objects would be considered excessive.  SNMP BER encoded protocol   elements are generally in a fairly compact encoding form compared   with text based forms (as used in some existing radius log file   implementations).  This interacts with the general requirement for   carrying service specific attributes and the accounting requirement   for extensibility.  With careful MIB design and future work on SNMP   payload compression the SNMP coding overhead can be comparable with   other less extensible protocols.   1.4.3 Accounting Record Extensibility - Grade T   SNMP has a strong tradition of allowing vendor specific data objects   to be transferred.   1.4.4 Batch Accounting - Grade T   There are many methods which a SNMP based system could use for batch   accounting.  The document discusses SNMP parameters to control the   batching process and indicates that certain existing MIBs contain   examples of implementation strategies.  SNMP log tables can provide   accounting information which can be obtained in many methods not   directly related to real time capabilities.  The underlying system   buffering requirements are similar regardless of the protocol used to   transport the information.   1.4.5 Guaranteed Delivery - Grade T   SNMP is very amenable to providing guaranteed delivery.  Particularly   in a pull model (versus the often assumed push model) the data   gatherer can absolutely know that all data has been transfered.  In   the common push model the data receiver does not know if the   originator of the data is having problems delivering the data.   1.4.6 Accounting Timestamps - Grade T   Timestamps are used for many SNMP based operations.  The document   points at the DateAndTime textual convention which is available for   use.  As with all environments the timestamps accuracy needs   evaluation before the information should be relied upon.Mitton, et al.               Informational                     [Page 26]

RFC 3127            AAA Protocol Evaluation Process            June 2001   1.4.7 Dynamic Accounting - Grade T   As long as there is some way to relate multiple records together   there are no problems resolving multiple records for the same   session.  This interacts with the scalability requirement and care   must be taken when implementing a system with both of these   requirements.   1.5 MOBILE IP Requirements   1.5.1 Encoding of MOBILE IP Registration Messages - Grade T   SNMP can easily provide objects to transfer this information.   1.5.2 Firewall Friendly - New Grade T (from P)   SNMP is already deployed in many operational networks.  SNMPv3   addresses most concerns people had with the operation of previous   versions.  True SNMPv3 proxies (as opposed to AAA proxies) should   become commonplace components in firewalls for those organizations   which require firewalls.   1.5.3 Allocation of Local Home Agent - New Grade T (from ?)   SNMP is not concerned with the LHA.  This can be under control of the   Local network to meet its needs.   2. Summary Discussion   SNMP appears to meet most stated requirements.  The areas where the   SNMP proposal falls short are areas where specific AAA architectures   are envisioned and requirements based upon that architecture are   specified.   Scaling of the protocol family is vital to success of a AAA suite.   The SNMP protocol has proved scalable in existing network management   and other high volume data transfer operations.  Care needs to be   taken in the design of a large scale system to ensure meeting the   desired level of service, but this is true of any large scale   project.   3. General Requirements   SNMP is well understood and already supported in many ISP and other   operational environments.  Trust models already exist in many cases   and can be adapted to provide the necessary access controls needed by   the AAA protocols.  Important issues with previous versions of SNMP   have been corrected in the current SNMPv3 specification.Mitton, et al.               Informational                     [Page 27]

RFC 3127            AAA Protocol Evaluation Process            June 2001   The SNMP proposal is silent on the specific data variables and   message types to be implemented.  This is largely due to the   requirements not specifying the necessary data elements and the time   constraints in extracting that information from the base document   set.  Such a data model is necessary regardless of the ultimate   protocol selected.   4. Summary Recommendation   SNMP appears to fully meet all necessary requirements for the full   AAA protocol family.C.2 SNMP CON Evaluation   Evaluation of SNMP AAA Requirements   CON Evaluation   Evaluator - Michael StJohns   Ref [1] is "Comparison of SNMPv3 Against AAA Network Access   Requirements", aka 'the document'   Ref [2] is the aaa eval criteria as modified by us.   The document uses T to indicate total compliance, P to indicate   partial compliance and F to indicate no compliance.  For each section   I've indicated my grade for the section.  If there is no change, I've   indicated that and the grade given by the authors.Section 1 - Per item discussion   1.1 General Requirements   1.1.1 Scalability - Although the document indicates compliance with   the requirement, its unclear how SNMP actually meets those   requirements.  The document neither discusses how SNMP will scale,   nor provides applicable references.  The argument that there is an   existence proof given the deployed SNMP systems appears to assume   that one manager contacting many agents maps to many agents (running   AAA) contacting one AAA server.  A server driven system has   substantially different scaling properties than a client driven   system and SNMP is most definitely a server (manager) driven system.   Eval - F   1.1.2 Fail-over - The document indicates the use of application level   time outs to provide this mechanism, rather than the mechanism being   a characteristic of the proposed protocol.  The protocol provides   only partial compliance with the requirement.  Eval - PMitton, et al.               Informational                     [Page 28]

RFC 3127            AAA Protocol Evaluation Process            June 2001   1.1.3 Mutual Authentication - There is some slight handwaving here,   but the protocol's USM mode should be able to support this   requirement.  Eval - No Change (T)   1.1.4 Transmission Level Security - The authors should elaborate on   the specific use of the SNMPv3 modes to support these requirements,   but the text is minimally acceptable.  Eval - No Change (T)   1.1.5 Data Object Confidentiality - The authors describe a mechanism   which does not appear to completely meet the requirement.  VACM is a   mechanism for an end system (agent) to control access to its data   based on manager characteristics.  This mechanism does not appear to   map well to this requirement.  Eval - P   1.1.6 Data Object Integrity - There appears to be some handwaving   going on here.  Again, SNMP does not appear to be a good match to   this requirement due to at least in part a lack of a proxy   intermediary concept within SNMP.  Eval - F   1.1.7 Certificate Transport - The document does indicate compliance,   but notes that optimization might argue for use of specialized   protocols.  Eval - No Change (T)   1.1.8 Reliable AAA Transport - The document indicates some confusion   with the exact extent of this requirement.  Given the modifications   suggested by the eval group to the explanatory text in [2] for the   related annotation, the point by point explanatory text is not   required.  The document does indicate that the use of SNMP is   irrespective of the underlying transport and the support of this   requirement is related at least partially to the choice of transport.   However, SNMP over UDP - the most common mode for SNMP - does not   meet this requirement.  Eval - No Change (P)   1.1.9 Run over IPv4 - While the evaluator agrees that SNMPv3 runs   over V4, the authors need to point to some sort of reference.  Eval -   No Change (T)   1.1.10 Run over IPv6 - The document indicates both experimental   implementations and future standardization of SNMPv3 over IPv6.  Eval   - No Change (P)   1.1.11 Support Proxy and Routing Brokers - The section of the   document (5.5.3) that, by title, should have the discussion of SNMP   proxy is marked as TBD.  The section notes that the inability to   completely comply with the data object confidentiality and integrity   requirements might affect the compliance of this section and the   evaluator agrees.  Eval - FMitton, et al.               Informational                     [Page 29]

RFC 3127            AAA Protocol Evaluation Process            June 2001   1.1.12 Auditability - The document indicates no compliance with this   requirement.  Eval - No Change (F)   1.1.13 Shared Secret Not Required - Slight handwaving here, but   SNMPv3 does not necessarily require use of its security services if   other security services are available.  However, the interaction with   VACM in the absence of USM is not fully described and may not have   good characteristics related to this requirement.  Eval - P   1.1.14 Ability to Carry Service Specific Attributes - SNMP complies   via the use of MIBs.  Eval - No Change (T)   1.2 Authentication Requirements   1.2.1 NAI Support - The document indicates that MIB objects can be   created to meet this requirement, but gives no further information.   Eval - P   1.2.2 CHAP Support - The document indicates that MIB objects can be   created to meet this requirement, but gives no further information.   Given the normal CHAP model, its unclear exactly how this would work.   Eval - F   1.2.3 EAP Support - The document notes that EAP payloads can be   carried as specific MIB objects, but also notes that further design   work would be needed to fully incorporate EAP.  Eval - No Change (P)   1.2.4 PAP/Clear-text Passwords - The document notes the use of MIB   objects to carry the clear text passwords and the protection of those   objects under normal SNMPv3 security mechanisms.  Eval - No Change   (T)   1.2.5 Reauthorization on demand - While there's some handwaving here,   its clear that the specific applications can generate the signals to   trigger reauthorization under SNMP.  Eval - No Change (T)   1.2.6 Authorization w/o Authentication - The author appears to be   confusing the AAA protocol authorization with the AAA user   authorization and seems to be over generalizing the ability of SNMP   to deal with general AAA user authorization.  Eval - F   1.3 Authorization Requirements   1.3.1 Static and Dynamic IP Addr Assignment - The reference to MIB   objects without more definite references or descriptions continues to   be a negative.  While the evaluator agrees that MIB objects can   represent addresses, the document needs to at least lead the reader   in the proper direction.  Eval - FMitton, et al.               Informational                     [Page 30]

RFC 3127            AAA Protocol Evaluation Process            June 2001   1.3.2 RADIUS Gateway Capability - The transport and manipulation of   Radius objects appears to be only a part of what is required.  Eval -   P   1.3.3 Reject Capability - Again, a clarification of how SNMP might   accomplish this requirement would be helpful.  The overall document   lacks a theory of operation for SNMP in an AAA role that might have   clarified the various approaches.  Eval - F   1.3.4 Preclude Layer 2 Tunneling - Document indicates lack of   understanding of this requirement.  Eval - F   1.3.5 Reauth on Demand - See response in 1.3.3 above.  None of the   text responding to this requirement, nor any other text in the   document, nor any of the references describes the appropriate   framework and theory.  Eval - F   1.3.6 Support for ACLs - The response text again references MIB   objects that can be defined to do this job.  There is additional   engineering and design needed before this is a done deal.  Eval - P   1.3.7 State Reconciliation - The text fails to address the basic   question of how to get the various parts of the AAA system back in   sync.  Eval - F   1.3.8 Unsolicited Disconnect - Assuming that the NAS is an SNMP agent   for an AAA server acting as an SNMP manager the evaluator concurs.   Eval - No Change (T).   1.4 Accounting Requirements   1.4.1 Real Time Accounting - SNMP Informs could accomplish the   requirements.  Eval - No Change (T)   1.4.2 Mandatory Compact Encoding - This is a good and reasonable   response.  SNMP can vary the style and type of reported objects to   meet specific needs.  Eval - No Change (T).   1.4.3 Accounting Record Extensibility - MIBs are extensible.  Eval -   No Change (T)   1.4.4 Batch Accounting - MIBs provide data collection at various   times.  Eval - No Change (T)   1.4.5 Guaranteed Delivery - There's some weasel wording here with   respect to what guaranteed means, but the description of mechanisms   does appear to meet the requirements.  Eval - No Change (T)Mitton, et al.               Informational                     [Page 31]

RFC 3127            AAA Protocol Evaluation Process            June 2001   1.4.6 Accounting Timestamps - Accounting records can use the   DateAndTime Textual Convention to mark their times.  Eval - No Change   (T)   1.4.7 Dynamic Accounting - The author may have partially missed the   point on this requirement.  While the number of records per session   is not of great interest, the delivery may be.  The author should go   a little more into depth on this requirement.  Eval - No Change (T)   1.5 MOBILE IP Requirements   1.5.1 Encoding of MOBILE IP Registration Messages - Registration   messages can probably be encoded as SNMP messages.  Eval - No Change   (T)   1.5.2 Firewall Friendly - There's a chicken and egg problem with the   response to the requirement in that the author hopes that SNMP as an   AAA protocol will encourage Firewall vendors to make SNMP a firewall   friendly protocol.  Eval - F   1.5.3 Allocation of Local Home Agent - The author disclaims an   understanding of this requirement.  Eval - F   2. Summary Discussion   The documents evaluation score was substantially affected by a lack   of any document, reference or text which described a theory of   operation for SNMP in AAA mode.  Of substantial concern are the items   relating to the AAA server to server modes and AAA client to server   modes and the lack of a map to the SNMP protocol for those modes.   The evaluator also notes that the scaling issues of SNMP in SNMP   agent/manager mode are in no way indicative of SNMP in AAA   client/server mode.  This has a possibility to substantially impair   SNMPs use in an AAA role.   However, SNMP may have a reasonable role in the Accounting space.   SNMP appears to map well with existing technology, and with the   requirements.   3. General Requirements   SNMP appears to meet the general requirements of an IP capable   protocol, but may not have a proper field of use for all specific   requirements.Mitton, et al.               Informational                     [Page 32]

RFC 3127            AAA Protocol Evaluation Process            June 2001   4. Summary Recommendation   Recommended in Part.  SNMP is NOT RECOMMENDED for use as either an   authentication or authorization protocol, but IS RECOMMENDED for use   as an accounting protocol.C.3 RADIUS+ PRO Evaluation   Evaluation of RADIUS AAA Requirements PRO Evaluation   Evaluator - Mark Stevens   Ref [1] is "Comparison of RADIUS Against AAA Network Access   Requirements"   Ref [2] is "Framework for the extension of the RADIUS(v2) protocol"   Ref [3] is the aaa eval criteria as modified by us.   The documents uses T to indicate total compliance, P to indicate   partial compliance and F to indicate no compliance.   For each section I've indicated my grade for the section.  I have   indicated whether or not my evaluation differs from the statements   made with respect to RADIUS++.  The evaluation ratings as given below   may differ from the evaluations codified in the document referred to   as, "Comparison of RADIUS Against AAA Network Access Requirements"   without any indication.   1.1 General Requirements   1.1.1 [a] Scalability - In as much as a protocol's scalability can be   measured, the protocol seems to transmit information in a fairly   efficient manner.So, in that the protocol appears not to consume an   inordinate amount of bandwidth relative to the data it is   transmitting, this protocol could be considered scalable.  However,   the protocol has a limit in the number of concurrent sessions it can   support between endpoints.  Work arounds exist and are in use.  Eval   - P (no change)   1.1.2 [b] Fail-over - The document indicates the use of application   level time outs to provide this mechanism, rather than the mechanism   being a characteristic of the proposed protocol.  The fail-over   requirement indicates that the protocol must provide the mechanism   rather than the application.  The implication is that the application   need not be aware that the fail-over and subsequent correction when   it happens.  The application using the RADIUS++ protocol will be   involved in fail-over recovery activities.  The protocol layer of the   software does not appear to have the capability built-in.  Given the   wording of the requirement: Eval - P (changed from T)Mitton, et al.               Informational                     [Page 33]

RFC 3127            AAA Protocol Evaluation Process            June 2001   1.1.3 [c] Mutual Authentication - The RADIUS++ protocol provides   shared-secret as a built-in facility for mutual authentication.  The   authors of the document suggest the use of IPSec to obtain mutual   authentication functions.  The RADIUS++ protocol provides no road   blocks to obtaining mutual authentication between instances of AAA   applications, however the protocol provides no facilities for doing   so.   1.1.4 [d] Transmission Level Security - The RADIUS++ protocol   provides no transmission level security features, nor does it   preclude the use of IPSec to obtain transmission level security.   Eval - P (no change)   1.1.5 [e] Data Object Confidentiality - The document describes a   RAIDUS++ message designed to server as an envelope in which encrypted   RADIUS messages (attributes) may be enclosed.  Eval - T (no change)   1.1.6 [f] Data Object Integrity - Using visible signatures, the   RADIUS++ protocol appears to meet this requirement.  Eval - T (no   change)   1.1.7 [g] Certificate Transport - The document indicates compliance   through the use of the CMS-Data Radius Attribute (message).  Eval - T   (no change)   1.1.8 [h] Reliable AAA Transport - The document points out that   RADIUS++ can be considered a reliable transport when augmented with   Layer 2 Tunneling Protocol.  The protocol itself does not provide   reliability features.  Reliability remains the responsibility of the   application or a augmenting protocol.  Eval - P (no change)   1.1.9 [i] Run over IPv4 - Eval - T (no change)   1.1.10 [j] Run over IPv6 - an IPv6 Address data type must be defined.   Eval - T (no change)   1.1.11 [k] Support Proxy and Routing Brokers - There is no mechanism   for rerouting requests, but an extension can be made to do so.  Eval   - T (no change)   1.1.12 [l] Auditability - The document indicates no compliance with   this requirement.  Eval - F (no change)   1.1.13 [m] Shared Secret Not Required - RADIUS++ can be configured to   run with empty shared secret values.  Eval - T (no change)Mitton, et al.               Informational                     [Page 34]

RFC 3127            AAA Protocol Evaluation Process            June 2001   1.1.14 [n] Ability to Carry Service Specific Attributes - Vendor   escape mechanism can be used for this purpose..  Eval - T  (no   change)   1.2 Authentication Requirements   1.2.1 [a] NAI Support -  Eval - T (no change)   1.2.2 [b] CHAP Support - Subject to dictionary attacks.  Eval - P   (changed from T)   1.2.3 [c] EAP Support - Eval - T (no change)   1.2.4 [d] PAP/Clear-text Passwords - No end-to-end security, but   potential for encapsulation exists within current paradigm of the   protocol.  -  Eval -T (no change)   1.2.5 [e] Reauthentication on demand -   The RADIUS protocol   supports re-authentication.  In  case  re-authentication is initiated   by the user or AAA client, the AAA client can send a new   authentication request.  Re-authentication can be initiated from the   visited or home AAA server by sending a challenge message to the AAA   client.  Eval - T (no change)   1.2.6 [f] Authorization w/o Authentication - A new message type can   be created to enable RADIUS++ to support Aw/oA .  Eval - T (no   change)   1.3 Authorization Requirements   1.3.1[a] Static and Dynamic IP Addr Assignment - Both supported.   IPv6 would require the definition of a new address data type.  Eval -   P (no change)   1.3.2 [b] RADIUS Gateway Capability - The transport and manipulation   of RADIUS objects appears to be only a part of what is required.   Requirement seems to be worded to preclude RADIUS.  Eval - P (changed   from T)   1.3.3 [c] Reject Capability -  Eval -T   1.3.4 [d] Preclude Layer 2 Tunneling -  I do not see a definition in   the AAA eval criteria document.  Eval - ?Mitton, et al.               Informational                     [Page 35]

RFC 3127            AAA Protocol Evaluation Process            June 2001   1.3.5 [e] Reauthorization on Demand - Implementation in the field   demonstrate that extensions to RADIUS can support the desired   behavior.  Re-authentication is currently coupled to re-   authorization.  Eval - P (no change)   1.3.6 [f] Support for ACLs - Currently done in the applications   behind the RADIUS end points, not the within the protocol.  RADIUS++   could define additional message types to deal with expanded access   control within new service areas.  Eval - P (no change)   1.3.7 [g] State Reconciliation -  Eval - F (no change)   1.3.8 [h] Unsolicited Disconnect - RADIUS++ extensions to support.   Eval - T. (no change)   1.4 Accounting Requirements   1.4.1 [a] Real Time Accounting -  Eval - T (no change)   1.4.2 [b] Mandatory Compact Encoding -  Eval - T (no change)   1.4.3 [c] Accounting Record Extensibility -  Eval - T (no change)   1.4.4 [d] Batch Accounting - RADIUS++ offers no new features to   support batch accounting.  Eval - F No change)   1.4.5 [e] Guaranteed Delivery - Retransmission algorithm employed.   Eval - T (no change)   1.4.6 [f] Accounting Timestamps - RADIUS++ extensions support   timestamps.  Eval - T (no change)   1.4.7 [g] Dynamic Accounting - RADIUS++ extensions to support.  Eval   - T (no change)   1.5 MOBILE IP Requirements   1.5.1 [a] Encoding of MOBILE IP Registration Messages - RADIUS++   extensions can be made to include registration messages as an opaque   payload.  Eval - T (no change)   1.5.2 [b] Firewall Friendly -  RADIUS  is  known  to  be  operational   in environments where firewalls acting as a proxy are active.  Eval -   T (no change)   1.5.3 [c] Allocation of Local Home Agent -Requirement statement needs   some clarification and refinement.  Eval - F (no change)Mitton, et al.               Informational                     [Page 36]

RFC 3127            AAA Protocol Evaluation Process            June 2001   2. Summary Discussion   The RADIUS protocol, and its associated extensions, is  presently not   fully  compliant  with  the AAA Network Access requirements.   However, it is  possible with a small effort to extend present   procedures to meet the requirements as listed in, while maintaining a   high level  of interoperability  with  the  wide  deployment  and   installed base of RADIUS clients and servers.   3. General Requirements   RADIUS++ the protocol and the application meet the majority of the   requirements and can be extended to meet the requirements where   necessary.   4. Summary Recommendation   RADIUS++ as it could be developed would provide a level of backward   compatibility that other protocols cannot achieve.  By extending   RADIUS in the simple ways described in the documents listed above,   the transition from existing RADIUS-based installations to RADIUS++   installations would be easier.  Although accounting continues to be   weaker than other approaches, the protocol remains a strong contender   for continued use in the areas of Authorization and Authentication.C.4 RADIUS+ CON Evaluation   Evaluation of RADIUS++ (sic) AAA Requirements CON Evaluation   Evaluator - David Nelson   Ref [1] is "Comparison of RADIUS Against AAA Network Access   Requirements", a.k.a. 'the document'   Ref [2] is "Framework for the extension of the RADIUS(v2) protocol",   a.k.a. 'the protocol'   Ref [3] is the AAA evaluation criteria as modified by us.   Ref [4] isRFC 2869.   Ref [5] is an expired work in progress "RADIUS X.509 Certificate   Extensions".   Ref [6] isRFC 2868   The document uses T to indicate total compliance, P to indicate   partial compliance and F to indicate no compliance.  Evaluator's   Note:  The document [1] pre-dates the protocol [2].  It is clear from   reading [2], that some of the issues identified as short comings in   [1] are now addressed in [2].  The evaluator has attempted to take   note of these exceptions, where they occur.Mitton, et al.               Informational                     [Page 37]

RFC 3127            AAA Protocol Evaluation Process            June 2001Section 1 - Per item discussion   1.1 General Requirements   1.1.1 Scalability - The document [1] indicates partial compliance,   largely in deference to the "tens of thousands of simultaneous   requests" language in [3], that has been deprecated.  The issue of   simultaneous requests from a single AAA client is addressed in [1],   indicating that the apparent limitation of 256 uniquely identifiable   outstanding request can be worked around using well known techniques,   such as the source UDP port number of the request.  The document   claims "P", and the evaluator concurs.   1.1.2 Fail-over - The document [1] indicates the use of application   level time outs to provide the fail-over mechanism.  Since the AAA   protocol is indeed an application-layer protocol, this seems   appropriate.  There are significant issues of how to handle fail-   over in a proxy-chain environment that have not been well addressed,   however.  The document claims "T", and the evaluator awards "P".   1.1.3 Mutual Authentication - The document [1] indicates that mutual   authentication exists in the presence of a User-Password or CHAP-   Password attribute in an Access-Request packet or the Message-   Authenticator [4] in any packet.  Once again, this addresses hop-by-   hop authentication of RADIUS "peers", but does not fully address   proxy-chain environments, in which trust models would need to be   established.  The document further indicates that strong mutual   authentication could be achieved using the facilities of IPsec.  This   claim would apply equally to all potential AAA protocols, and cannot   be fairly said to be a property of the protocol itself.  The document   claims "T", and the evaluator awards "F".   1.1.4 Transmission Level Security - The document [1] indicates that   transmission layer security, as defined in [3], is provided in the   protocol, using the mechanisms described insection 1.1.3.  It should   be noted that this requirement is now a SHOULD in [3].  The document   claims "P", and the evaluator concurs.   1.1.5 Data Object Confidentiality - The document [1] indicates that   end-to-end confidentiality is not available in RADIUS, but goes on to   say that it could be added.  The protocol [2] actually makes an   attempt to specify how this is to be done, insection 4.3.2.2 of [2],   using a CMS-data attribute, based in large part uponRFC 2630.  The   evaluator has not, at this time, investigated the applicability ofRFC 2630 to the AAA work.  The document claims "F", but in light of   the specifics of the protocol [2], the evaluator awards "P".Mitton, et al.               Informational                     [Page 38]

RFC 3127            AAA Protocol Evaluation Process            June 2001   1.1.6 Data Object Integrity - The document [1] indicates that end-   to-end integrity is not available in RADIUS, but goes on to say that   it could be added.  The protocol [2] actually makes an attempt to   specify how this is to be done, insection 4.3.2.1 of [2], using a   CMS-data attribute, based in large part uponRFC 2630.  The evaluator   has not, at this time, investigated the applicability ofRFC 2630 to   the AAA work.  The document claims "F", but in light of the specifics   of the protocol [2], the evaluator awards "P".   1.1.7 Certificate Transport - The document [1] indicates that   certificate transport is not available in RADIUS, but goes on to say   that it could be added.  The protocol [2] actually makes an attempt   to specify how this is to be done, insection 4.3.2.3 of [2], using a   CMS-data attribute, based in large part uponRFC 2630.  The evaluator   has not, at this time, investigated the applicability ofRFC 2630 to   the AAA work.  Other relevant work in the area of certificate support   in RADIUS may be found in an expired work in progress, "RADIUS X.509   Certificate Extensions" [5].  The document claims "F", but in light   of the specifics of the protocol [2], the evaluator awards "P".   1.1.8 Reliable AAA Transport - The document [1] indicates that RADIUS   provides partial compliance with the requirements of the original AAA   requirements document.  However, in [3], the requirement has been   simplified to "resilience against packet loss".  Once again, the   evaluator finds that the protocol [2] meets this criteria on a hop-   by-hop basis, but fails to effectively address these issues in a   proxy-chain environment.  The document claims "P", and the evaluator   awards "F".   1.1.9 Run over IPv4 - RADIUS is widely deployed over IPv4.  The   document claims "T", and the evaluator concurs.   1.1.10 Run over IPv6 - The document [1] indicates that adoption of a   limited number of new RADIUS attributes to support IPv6 is   straightforward.  Such discussion has transpired on the RADIUS WG   mailing list, although that WG is in the process of shutting down.   The document claims "P", and the evaluator concurs.   1.1.11 Support Proxy and Routing Brokers - The document [1] indicates   that RADIUS is widely deployed in proxy-chains of RADIUS servers.   This is equivalent to the Proxy Broker case, but the Routing Broker   case is a different requirement.  The protocol [2] does not describe   any detail of how a Routing Broker might be accommodated, although it   opens the door by indicating that the RADIUS++ protocol is peer-to-   peer, rather than client/server.  The document claims "P", and the   evaluator awards "F".Mitton, et al.               Informational                     [Page 39]

RFC 3127            AAA Protocol Evaluation Process            June 2001   1.1.12 Auditability - The document [1] indicates no compliance with   this requirement.  The document claims "F", and the evaluator   concurs.   1.1.13 Shared Secret Not Required - The document [1] indicates that   RADIUS may effectively skirt the requirement of application-layer   security by using a value of "zero" for the pre-shared secret.  While   this is a bit creative, it does seem to meet the requirement.  The   document claims "T" and the evaluator concurs.   1.1.14 Ability to Carry Service Specific Attributes - RADIUS has a   well defined Vendor-Specific Attribute, which, when properly used,   does indeed provide for the ability to transport service-specific   attributes.  The document claims "T", and the evaluator concurs.   1.2 Authentication Requirements   1.2.1 NAI Support - The document [1] indicates that RADIUS specifies   the NAI as one of the suggested formats for the User-Name attribute.   The document claims "T", and the evaluator agrees.   1.2.2 CHAP Support - CHAP support is widely deployed in RADIUS.  The   document claims [1] "T", and the evaluator concurs.   1.2.3 EAP Support - The document [1] indicates that EAP support in   RADIUS is specified in [4].  The document claims [1] "T", and the   evaluator concurs.   1.2.4 PAP/Clear-text Passwords - The document [1] indicates that   RADIUS provides protection of clear-text passwords on a hop-by-hop   basis.  The protocol [2] indicates how additional data   confidentiality may be obtained insection 4.3.2.2 of [2], using a   CMS-data attribute, based in large part uponRFC 2630.  The evaluator   has not, at this time, investigated the applicability ofRFC 2630 to   the AAA work.  The document claims [1] "F", but in light of the   specifics of the protocol [2], the evaluator awards "P".   1.2.5 Reauthentication on demand - The document [1] indicates that   RADIUS may accomplish re-authentication on demand by means of an   Access-Challenge message sent from a server to a client.  The   evaluator disagrees that this is likely to work for a given session   once an Access-Accept message has been received by the client.  The   document claims "T", and the evaluator awards "F".   1.2.6 Authorization w/o Authentication - This requirement, as applied   to the protocol specification, mandates that non- necessary   authentication credentials not be required in a request for   authorization.  The actual decision to provide authorization in theMitton, et al.               Informational                     [Page 40]

RFC 3127            AAA Protocol Evaluation Process            June 2001   absence of any authentication resides in the application (e.g. AAA   server).  RADIUS does require some form of credential in request   messages.  The document [1] claims "F", and the evaluator concurs.   1.3 Authorization Requirements   1.3.1 Static and Dynamic IP Addr Assignment - The document [1]   indicates that RADIUS can assign IPv4 addresses, and can easily be   extended to assign IPv6 addresses (seesection 1.1.10).  Of greater   concern, however, is the issue of static vs. dynamic addresses.  If   dynamic address has the same meaning as it does for DHCP, then there   are issues of resource management that RADIUS has traditionally not   addressed.  The document claims "P", and the evaluator concurs.   1.3.2 RADIUS Gateway Capability - The document [1] maintains that a   RADIUS++ to RADIUS gateway is pretty much a tautology.  The document   claims "T", and the evaluator concurs.   1.3.3 Reject Capability - The document [1] maintains that RADIUS   Proxy Servers, and potentially RADIUS++ Routing Brokers, have the   ability to reject requests based on local policy.  The document   claims "T" and the evaluator concurs.   1.3.4 Preclude Layer 2 Tunneling - The document [1] indicates that   [6] defines support for layer two tunneling in RADIUS.  The document   claims "T", and the evaluator concurs.   1.3.5 Reauth on Demand - The document [1] indicates that RADIUS   provides this feature by means of the Session-Timeout and   Termination- Action attributes.  While this may, in fact, be   sufficient to provide periodic re-authorization, it would not provide   re- authorization on demand.  The protocol [2] does not address this   further.  The document claims "P", and the evaluator awards "F".   1.3.6 Support for ACLs - The document [1] describes the attributes in   RADIUS that are used to convey the access controls described in [3].   Certain of these (e.g. QoS) are not currently defined in RADIUS, but   could easily be defined as new RADIUS attributes.  The document   claims "P", and the evaluator concurs.   1.3.7 State Reconciliation - The document [1] addresses each of the   sub- items, as listed in the original AAA requirements document.  In   reviewing the document against the modified requirements of [3],   there is still an issue with server-initiated state reconciliation   messages.  While the protocol [2] makes provision for such messages,   as servers are allowed to initiate protocol dialogs, no detailedMitton, et al.               Informational                     [Page 41]

RFC 3127            AAA Protocol Evaluation Process            June 2001   message formats are provided.  This is an area that has traditionally   been a short coming of RADIUS.  The document claims "P", and the   evaluator awards "F".   1.3.8 Unsolicited Disconnect - Much of the discussion from the   previous section applies to this section.  The document [1] claims   "F", and the evaluator concurs.   1.4 Accounting Requirements   1.4.1 Real Time Accounting - RADIUS Accounting is widely deployed and   functions within the definition of real time contained in [3].  The   document [1] claims "T", and the evaluator concurs.   1.4.2 Mandatory Compact Encoding - RADIUS Accounting contains TLVs   for relevant accounting information, each of which is fairly compact.   Note that the term "bloated" in [3] is somewhat subjective.  The   document [1] claims "T", and the evaluator concurs.   1.4.3 Accounting Record Extensibility - RADIUS Accounting may be   extended by means of new attributes or by using the Vendor-Specific   attribute.  While it has been argued that the existing attribute   number space is too small for the required expansion capabilities,   the protocol [2] addresses this problem insection 3.0, and its   subsections, of [2].  The document [1] claims "T", and the evaluator   concurs.   1.4.4 Batch Accounting - RADIUS has no explicit provisions for batch   accounting, nor does the protocol [2] address how this feature might   be accomplished.  The document [1] claims "F", and the evaluator   concurs.   1.4.5 Guaranteed Delivery - RADIUS Accounting is widely deployed and   provides guaranteed delivery within the context of the required   application-level acknowledgment.  The document [1] claims "T", and   the evaluator concurs.   1.4.6 Accounting Timestamps - The document [1] indicates that this   feature is specified in [4] as the Event-Timestamp attribute.  The   document claims [1] "T", and the evaluator concurs.   1.4.7 Dynamic Accounting - The document [1] indicates that this   requirement is partially met using the accounting interim update   message as specified in [4].  In addition, there was work in the   RADIUS WG regarding session accounting extensions that has not been   included in [4], i.e., some expired works in progress.  The document   claims [1] "P", and the evaluator concurs.Mitton, et al.               Informational                     [Page 42]

RFC 3127            AAA Protocol Evaluation Process            June 2001   1.5 MOBILE IP Requirements   1.5.1 Encoding of MOBILE IP Registration Messages - The document [1]   claims "F", and the evaluator concurs.   1.5.2 Firewall Friendly - The document [1] indicates that RADIUS   deployment is know to have occurred in fire-walled environments.  The   document claims "T", and the evaluator concurs.   1.5.3 Allocation of Local Home Agent - The document [1] claims "F",   and the evaluator concurs.   2. Summary Discussion   The document [1] and the protocol [2] suffer from having been written   in a short time frame.  While the protocol does provide specific   guidance on certain issues, citing other relevant documents, it is   not a polished protocol specification, with detailed packet format   diagrams.  There is a pool of prior work upon which the RADIUS++   protocol may draw, in that many of the concepts of Diameter were   first postulated as works in progress within the RADIUS WG, in an   attempt to "improve" the RADIUS protocol.  All of these works in   progress have long since expired, however.   3. General Requirements   RADIUS++ meets many of the requirements of an AAA protocol, as it is   the current de facto and de jure standard for AAA.  There are long-   standing deficiencies in RADIUS, which have been well documented in   the RADIUS and NASREQ WG proceedings.  It is technically possible to   revamp RADIUS to solve these problems.  One question that will be   asked, however, is:  "What significant differences would there be   between a finished RADIUS++ protocol and the Diameter protocol?".   4. Summary Recommendation   Recommended in part.  What may possibly be learned from this   submission is that it is feasible to have a more RADIUS-compliant   RADIUS-compatibility mode in Diameter.Mitton, et al.               Informational                     [Page 43]

RFC 3127            AAA Protocol Evaluation Process            June 2001C.5 Diameter PRO Evaluation   Evaluation of Diameter against the AAA Requirements   PRO Evaluation   Evaluator - Basavaraj Patil   Ref [1] is "Diameter Framework Document".   Ref [2] is "Diameter NASREQ Extensions".   Ref [3] is the AAA evaluation criteria as modified by us.   Ref [4] is "Diameter Accounting Extensions".   Ref [5] is "Diameter Mobile IP Extensions".   Ref [6] is "Diameter Base Protocol".   Ref [7] is "Diameter Strong Security Extension".   Ref [8] is "Comparison of Diameter Against AAA Network Access   Requirements".   The document uses T to indicate total compliance, P to indicate   partial compliance and F to indicate no compliance.   Evaluator's note : The Diameter compliance document [8] claims Total   "T" compliance with all the requirements except :  - 1.2.5 - 1.5.2Section 1 - Per item discussion   1.1 General Requirements   1.1.1 Scalability   Diameter is an evolution of RADIUS and has taken into consideration   all the lessons learned over many years that RADIUS has been in   service.  The use of SCTP as the transport protocol reduces the need   for multiple proxy servers (Sec 3.1.1 Proxy Support of [1]) as well   as removing the need for application level acks.  The use and support   of forwarding and redirect brokers enhances  scalability.  Evaluator   concurs with the "T" compliance on this requirement.   1.1.2 Fail-over   Again with the use of SCTP, Diameter is able to detect disconnect   indications upon which it switches to an alternate server (Sec 4.0   [6]).  Also Requests and Responses do not have to follow the same   path and this increases the reliability.  Evaluator concurs with the   "T" compliance on this requirement.Mitton, et al.               Informational                     [Page 44]

RFC 3127            AAA Protocol Evaluation Process            June 2001   1.1.3 Mutual Authentication   The compliance document quotes the use of symmetric transforms for   mutual authentication between the client and server (Sec 7.1 of   [6]).  The use of IPSec as an underlying security mechanism and   thereby use the characteristics of IPSec itself to satisfy this   requirement is also quoted.  Evaluator concurs with the "T"   compliance on this requirement.   1.1.4 Transmission Level Security   Although this requirement has been deprecated by the AAA evaluation   team the document complies with it based on the definition (referring   to hop-by-hop security).Section 7.1 of [6] provides the details of   how this is accomplished in Diameter.  Evaluator concurs with the "T"   compliance on this requirement.   1.1.5 Data Object Confidentiality   This requirement seems to have come from Diameter.  Ref [7] explains   in detail the use of Cryptographic Message Syntax (CMS) to achieve   data object confidentiality.  A CMS-Data AVP is defined in [7].   Evaluator concurs with the "T" compliance on this requirement.   1.1.6 Data Object Integrity   Using the same argument as above and the hop-by-hop security feature   in the protocol this requirement is completely met by Diameter.   Evaluator concurs with the "T" compliance on this requirement.   1.1.7 Certificate Transport   Again with the use of the CMS-Data AVP, objects defined as these   types of attributes allow the transport of certificates.  Evaluator   concurs with the "T" compliance on this requirement.   1.1.8 Reliable AAA Transport   Diameter recommends that the protocol be run over SCTP.  SCTP   provides the features described for a reliable AAA transport.   Although the compliance is not a perfect fit for the definition of   this tag item, it is close enough and the functionality achieved by   using SCTP is  the same.  Evaluator concurs with the "T" compliance   on this requirement.Mitton, et al.               Informational                     [Page 45]

RFC 3127            AAA Protocol Evaluation Process            June 2001   1.1.9 Run over IPv4   Is an application layer protocol and does not depend on the   underlying version of IP.  Evaluator concurs with the "T" compliance   on this requirement.   1.1.10 Run over IPv6   Is an application layer protocol and does not depend on the   underlying version of IP.  Evaluator concurs with the "T" compliance   on this requirement.   1.1.11 Support Proxy and Routing BrokersSection 3.1.1/2 of the framework document [1] provides an explanation   of how Diameter supports proxy and routing brokers.  In fact it   almost appears as though the requirement for a routing broker came   from Diameter.  Evaluator concurs with the "T" compliance on this   requirement.   1.1.12 Auditability   With the use of CMS-Data AVP [7] a trail is created when proxies are   involved in the transaction.  This trail can provide auditability.   Evaluator concurs with the "T" compliance on this requirement.   1.1.13 Shared Secret Not Required   With the use of IPSec as the underlying security mechanism, Diameter   does not require the use of shared secrets for message   authentication.  Evaluator concurs with the "T" compliance on this   requirement.   1.1.14 Ability to Carry Service Specific Attributes   The base protocol [6] is defined by Diameter and any one else can   define specific extensions on top of it.  Other WGs in the IETF can   design an extension on the base protocol with specific attributes and   have them registered by IANA.  Evaluator concurs with the "T"   compliance on this requirement.Mitton, et al.               Informational                     [Page 46]

RFC 3127            AAA Protocol Evaluation Process            June 2001   1.2 Authentication Requirements   1.2.1 NAI Support   The base protocol [6] defines an AVP that can be used to support   NAIs.  Diameter goes one step further by doing Message forwarding   based on destination NAI AVPs.  Evaluator concurs with the "T"   compliance on this requirement.   1.2.2 CHAP Support   Reference [2]section 3.0 describes the support for CHAP.  Evaluator   concurs with the "T" compliance on this requirement.   1.2.3 EAP Support   Reference [2]section 4.0 describes the support for EAP.  Evaluator   concurs with the "T" compliance on this requirement.   1.2.4 PAP/Clear-text Passwords   Reference [2]section 3.1.1.1 describes the support for PAP.   Evaluator concurs with the "T" compliance on this requirement.   1.2.5 Reauthentication on demand   The use of Session-Timeout AVP as the mechanism for reauthentication   is claimed by the compliance document.  However no direct references   explaining this in the base protocol [6] document were found.   Evaluator deprecates the compliance on this to a "P"   Note: However this is a trivial issue.   1.2.6 Authorization w/o Authentication   Diameter allows requests to be sent without having any authentication   information included.  A Request-type AVP is defined in [2] and it   can specify authorization only without containing any authentication.   Evaluator concurs with the "T" compliance on this requirement.Mitton, et al.               Informational                     [Page 47]

RFC 3127            AAA Protocol Evaluation Process            June 2001   1.3 Authorization Requirements   1.3.1 Static and Dynamic IP Addr Assignment   The base protocol includes an AVP for carrying the  address.   References [6.2.2 of 2] and [4.5 of 5] provide detailed  explanations   of how this can be done.  Evaluator concurs with the "T" compliance   on this requirement.   1.3.2 RADIUS Gateway Capability   One of the basic facets of Diameter is to support backward   compatibility and act as a RADIUS gateway in certain environments.   Evaluator concurs with the "T" compliance on this requirement.   1.3.3 Reject Capability   Based on the explanation provided in the compliance document for this   requirement evaluator concurs with the "T" compliance on this   requirement.   1.3.4 Preclude Layer 2 Tunneling   Ref [2] defines AVPs supporting L2 tunnels  Evaluator concurs with   the "T" compliance on this requirement.   1.3.5 Reauth on Demand   A session timer defined in [6] is used for reauthorization.  However   Diameter allows reauthorization at any time.  Since this is a peer-   to-peer type of protocol any entity can initiate a reauthorization   request.  Evaluator concurs with the "T" compliance on this   requirement.   1.3.6 Support for ACLs   Diameter defines two methods.  One that supports backward   compatibility for RADIUS and another one with the use of a standard   AVP with the filters encoded in it.  Evaluator concurs with the "T"   compliance on this requirement.   1.3.7 State Reconciliation   A long explanation on each of the points defined for this tag item in   the requirements document.  Evaluator concurs with the "T" compliance   for this requirement.Mitton, et al.               Informational                     [Page 48]

RFC 3127            AAA Protocol Evaluation Process            June 2001   1.3.8 Unsolicited Disconnect   The base protocol [6] defines a set of session termination messages   which can be used for unsolicited disconnects.  Evaluator concurs   with the "T" compliance on this requirement.   1.4 Accounting Requirements   1.4.1 Real Time Accounting   Evaluator concurs with the "T" compliance based on explanations in   [4].   1.4.2 Mandatory Compact Encoding   Use of Accounting Data Interchange Format (ADIF)-Record-AVP for   compact encoding of accounting data.  Evaluator concurs with the "T"   compliance.   1.4.3 Accounting Record Extensibility   ADIF can be extended.  Evaluator concurs with the "T" compliance.   1.4.4 Batch Accounting   Sec 1.2 of [4] provides support for batch accounting.   1.4.5 Guaranteed Delivery   Sections2.1/2 of [4] describe messages that are used to guarantee   delivery of accounting records.  Evaluator concurs with the "T"   compliance.   1.4.6 Accounting Timestamps   Timestamp AVP [6] is present in all accounting messages.  Evaluator   concurs with the "T" compliance.   1.4.7 Dynamic Accounting   Interim accounting records equivalent to a call-in-progress can be   sent periodically.  Evaluator concurs with the "T" compliance.Mitton, et al.               Informational                     [Page 49]

RFC 3127            AAA Protocol Evaluation Process            June 2001   1.5 MOBILE IP Requirements   1.5.1 Encoding of MOBILE IP Registration Messages   Ref [5] provides details of how Diameter can encode MIP messages.   Evaluator concurs with the "T" compliance.   1.5.2 Firewall Friendly   Some handwaving here and a possible way of solving the firewall   problem with a Diameter proxy server.  Document claims "T", evaluator   deprecates it to a "P"   1.5.3 Allocation of Local Home Agent   Diameter can assign a local home agent in a visited network in   conjunction with the FA in that network.  Evaluator concurs with the   "T"   Summary Recommendation   Diameter is strongly recommended as the AAA protocol.  The experience   gained from RADIUS deployments has been put to good use in the design   of this protocol.  It has also been designed with extensibility in   mind thereby allowing different WGs to develop their own specific   extension to satisfy their requirements.  With the use of SCTP as the   transport protocol, reliability is built in.  Security has been   addressed in the design of the protocol and  issues that were   discovered in RADIUS have been fixed.  Diameter also  is a session   based protocol which makes it more scalable.  The support for   forwarding and redirect brokers is well defined and  this greatly   improves the scalability aspect of the protocol.   Lastly the protocol has been implemented by at least a few people and   interop testing done.  This in itself is a significant step and a   positive point for Diameter to be the AAA protocol.C.6 Diameter CON Evaluation   Evaluation of Diameter against the AAA Requirements   CON Brief   Evaluator: Barney WolffMitton, et al.               Informational                     [Page 50]

RFC 3127            AAA Protocol Evaluation Process            June 2001Section 1 - Per item discussion   1.1 General Requirements   1.1.1 Scalability - P (was T)  The evaluator is concerned with   scalability to the small, not to the large.  Diameter/SCTP may prove   difficult to retrofit to existing NAS equipment.   1.1.2 Fail-over - P (was T)  SCTP gives an indication of peer   failure, but nothing in any Diameter or SCTP document the evaluator   was able to find even mentions how or when to switch back to a   primary server to which communication was lost.  After a failure, the   state machines end in a CLOSED state and nothing seems to trigger   exit from that state.  It was not clear whether a server, on   rebooting, would initiate an SCTP connection to all its configured   clients.  If not, and in any case when the communication failure was   in the network rather than in the server, the client must itself,   after some interval, attempt to re-establish communication.  But no   such guidance is given.   Of course, the requirement itself fails to mention the notion of   returning to a recovered primary.  That is a defect in the   requirement.  The evaluator has had unfortunate experience with a   vendor's RADIUS implementation that had exactly the defect that it   often failed to notice recovery of the primary.   1.1.3 Mutual Authentication - T   1.1.4 Transmission Level Security - T   1.1.5 Data Object Confidentiality - P (was T).  Yes, the CMS data   type is supported.  But the work in progress, "Diameter Strong   Security Extension", says:      Given that asymmetric transform operations are expensive, Diameter      servers MAY wish to use them only when dealing with inter-domain      servers, as shown in Figure 3.  This configuration is normally      desirable since Diameter entities within a given administrative      domain MAY inherently trust each other.  Further, it is desirable      to move this functionality to the edges, since NASes do not      necessarily have the CPU power to perform expensive cryptographic      operations.   Given all the fuss that has been made about "end-to-end"   confidentiality (which really means "NAS-to-home_server"), the   evaluator finds it absurd that the proposed solution is acknowledged   to be unsuited to the NAS.Mitton, et al.               Informational                     [Page 51]

RFC 3127            AAA Protocol Evaluation Process            June 2001   1.1.6 Data Object Integrity - P (was T).  See above.   1.1.7 Certificate Transport - T   1.1.8 Reliable AAA Transport - T   1.1.9 Run over IPv4 - T   1.1.10 Run over IPv6 - T   1.1.11 Support Proxy and Routing Brokers - T   1.1.12 Auditability - T (based on our interpretation as non-   repudiation, rather than the definition given in reqts)   1.1.13 Shared Secret Not Required - T   1.1.14 Ability to Carry Service Specific Attributes - T   1.2 Authentication Requirements   1.2.1 NAI Support - T   1.2.2 CHAP Support - T   1.2.3 EAP Support - T   1.2.4 PAP/Clear-text Passwords - T   1.2.5 Reauthentication on demand - P (was T).  No mechanism was   evident for the server to demand a reauthentication, based for   example on detection of suspicious behavior by the user.  Session-   timeout is not sufficient, as it must be specified at the start.   1.2.6 Authorization w/o Authentication - T   1.3 Authorization Requirements   1.3.1 Static and Dynamic IP Addr Assignment - T   1.3.2 RADIUS Gateway Capability - P (was T).  RADIUS has evolved from   the version on which Diameter was based.  EAP is a notable case where   the convention that the Diameter attribute number duplicates the   RADIUS one is violated.  No protocol, not even RADIUS++, can claim a   T on this.   1.3.3 Reject Capability - T (The evaluator fails to understand how   any AAA protocol could rate anything other than T on this.)Mitton, et al.               Informational                     [Page 52]

RFC 3127            AAA Protocol Evaluation Process            June 2001   1.3.4 Preclude Layer 2 Tunneling - T   1.3.5 Reauth on Demand - P (was T).  As with reauthentication, there   is no evident mechanism for the server to initiate this based on   conditions subsequent to the start of the session.   1.3.6 Support for ACLs - P (was T).  The evaluator finds the Filter-   Rule AVP laughably inadequate to describe filters.  For example, how   would it deal with restricting SMTP to a given server, unless all IP   options are forbidden so the IP header length is known?  No real NAS   could have such an impoverished filter capability, or it would not   survive as a product.   1.3.7 State Reconciliation - P (was T).  It is difficult for the   evaluator to understand how this is to work in a multi-administration   situation, or indeed in any proxy situation.  Furthermore, SRQ with   no session-id is defined to ask for info on all sessions, not just   those "owned" by the requester.   1.3.8 Unsolicited Disconnect - T   1.4 Accounting Requirements   1.4.1 Real Time Accounting - T   1.4.2 Mandatory Compact Encoding - T   1.4.3 Accounting Record Extensibility - T   1.4.4 Batch Accounting - P (was T).  The evaluator suspects that   simply sending multiple accounting records in a single request is not   how batch accounting should or will be done.   1.4.5 Guaranteed Delivery - T   1.4.6 Accounting Timestamps - T  (The evaluator notes with amusement   that NTP time cycles in 2036, not 2038 as claimed in the Diameter   drafts.  It's Unix time that will set the sign bit in 2038.)   1.4.7 Dynamic Accounting - T   1.5 MOBILE IP Requirements   1.5.1 Encoding of MOBILE IP Registration Messages - T   1.5.2 Firewall Friendly - F (was T).  Until such time as firewalls   are extended to know about or proxy SCTP, it is very unlikely that   SCTP will be passed.  Even then, the convenient feature of being ableMitton, et al.               Informational                     [Page 53]

RFC 3127            AAA Protocol Evaluation Process            June 2001   to send a request from any port, and get the reply back to that port,   means that a simple port filter will not be sufficient, and   statefulness will be required.  Real friendship would require that   both source and dest ports be 1812.   1.5.3 Allocation of Local Home Agent - T   2. Summary Discussion   In some areas, Diameter is not completely thought through.  In   general, real effort has gone into satisfying a stupendous range of   requirements.   3. General Requirements   Diameter certainly fails the KISS test.  With SCTP, the drafts add up   to 382 pages - well over double the size of RADIUS even with   extensions.  The evaluator sympathizes with the political instinct   when faced with a new requirement no matter how bizarre, to say "we   can do that" and add another piece of filigree.  But the major places   where Diameter claims advantage over RADIUS, namely "end-to-end"   confidentiality and resource management, are just the places where   some hard work remains, if the problems are not indeed intractable.   More specifically, the evaluator sees no indication that specifying   the separate transport protocol provided any advantage to defray the   large increase in complexity.  Application acks are still required,   and no benefit from the transport acks was evident to the evaluator.   Nor was there any obvious discussion of why "sequenced in-order"   delivery is required, when AAA requests are typically independent.   SCTP offers out-of-order delivery, but Diameter seems to have chosen   not to use that feature.   Whether TLV encoding or ASN.1/BER is superior is a religious   question, but Diameter manages to require both, if the "strong"   extension is implemented.  The evaluator has a pet peeve with length   fields that include the header, making small length values invalid,   but that is a minor point.   Finally, interoperability would be greatly aided by defining a   standard "dictionary" format by which an implementation could adopt   wholesale a set of attributes, perhaps from another vendor, and at   least know how to display them.  That is one of the advantages of   MIBs.Mitton, et al.               Informational                     [Page 54]

RFC 3127            AAA Protocol Evaluation Process            June 2001   4. Summary Recommendation   Diameter is clearly close enough to meeting the myriad requirements   that it is an acceptable candidate, though needing some polishing.   Whether the vast increase in complexity is worth the increase in   functionality over RADIUS is debatable.C.7 COPS PRO Evaluation   Evaluation of COPS AAA Requirements   PRO Evaluation   Evaluator - David Nelson   Ref [1] is "Comparison of COPS Against the AAA NA Requirements", work   in progress, a.k.a. 'the document'   Ref [2] isRFC 2748 a.k.a. 'the protocol'   Ref [3] is the AAA evaluation criteria as modified by us.   Ref [4] is "AAA Protocols: Comparison between RADIUS, Diameter, and   COPS"  work in progress.   Ref [5] is "COPS Usage for AAA", work in progress.   This document uses T to indicate total compliance, P to indicate   partial compliance and F to indicate no compliance.Section 1 - Per item discussion   1.1 General Requirements   1.1.1 Scalability - The document [1] claims "T", and the evaluator   concurs.   1.1.2 Fail-over - The document [1] claims "T", and the evaluator   concurs.   1.1.3 Mutual Authentication - The document claims "T", and the   evaluator concurs.   1.1.4 Transmission Level Security - The document [1] indicates that   transmission layer security, as defined in [3], is provided in the   protocol, using the mechanisms described in [2].  It should be noted   that this requirement is now a SHOULD in [3].  The document claims   "T", and the evaluator concurs.   1.1.5 Data Object Confidentiality - The document [1] indicates that   end-to-end confidentiality is provided using a CMS-data attribute,   based in large part uponRFC 2630.  The evaluator has not, at this   time, investigated the applicability ofRFC 2630 to the AAA work.   The document claims "T", and the evaluator concurs.Mitton, et al.               Informational                     [Page 55]

RFC 3127            AAA Protocol Evaluation Process            June 2001   1.1.6 Data Object Integrity - The document [1] indicates that data   object integrity is provided using a CMS-data attribute, based in   large part uponRFC 2630.  The evaluator has not, at this time,   investigated the applicability ofRFC 2630 to the AAA work.  The   document claims "T", and the evaluator concurs.   1.1.7 Certificate Transport - The document [1] indicates that   certificate transport is provided using a CMS-data attribute, based   in large part uponRFC 2630 andRFC 1510.  The evaluator has not, at   this time, investigated the applicability ofRFC 2630 to the AAA   work.  The document claims "T", and the evaluator concurs.   1.1.8 Reliable AAA Transport - The document [1] indicates that COPS   uses TCP, which certainly meets the requirements for a reliable   transport.  The document claims "T", and the evaluator concurs.   1.1.9 Run over IPv4 - The document [1] claims "T", and the evaluator   concurs.   1.1.10 Run over IPv6 - The document [1] claims "T", and the evaluator   concurs.   1.1.11 Support Proxy and Routing Brokers - Reasonable detail of proxy   operations is provided in [5].  The document [1] claims "T", and the   evaluator concurs.   1.1.12 Auditability - The document [1] alludes to a History PIB that   would enable auditing without explaining how it would work.  The AAA   Extension [5] does not provide additional insight.  The document   claims "T", and the evaluator awards "P".   1.1.13 Shared Secret Not Required - The document [1] claims "T" and   the evaluator concurs.   1.1.14 Ability to Carry Service Specific Attributes -  The document   [1] claims "T", and the evaluator concurs.   1.2 Authentication Requirements   1.2.1 NAI Support - The document [1] indicates that NAI is to be   supported in the Information Model, but notes that for cases where   certificates are in use, the more restrictive syntax ofRFC 2459   applies.  The document claims "T", and the evaluator awards "P".   1.2.2 CHAP Support - The document [1] claims "T", and the evaluator   concurs.Mitton, et al.               Informational                     [Page 56]

RFC 3127            AAA Protocol Evaluation Process            June 2001   1.2.3 EAP Support - The document [1] claims "T", and the evaluator   concurs.   1.2.4 PAP/Clear-text Passwords - The document [1] indicates   compliance, presumably using a CMS-data attribute, based in large   part uponRFC 2630.  The evaluator has not, at this time,   investigated the applicability ofRFC 2630 to the AAA work.  The   document claims "T", and the evaluator concurs.   1.2.5 Reauthentication on demand - The document [1] claims "T", and   the evaluator concurs.   1.2.6 Authorization w/o Authentication - This requirement, as applied   to the protocol specification, mandates that non- necessary   authentication credentials not be required in a request for   authorization.  The actual decision to provide authorization in the   absence of any authentication resides in the application (e.g. AAA   server).  The document [1] claims "T", and the evaluator concurs.   1.3 Authorization Requirements   1.3.1 Static and Dynamic IP Addr Assignment -  The document [1]   claims "T", and the evaluator concurs.   1.3.2 RADIUS Gateway Capability - The document [1] claims "T", and in   the absence of any detailed discussion of how this is accomplished,   in either [1] or [5], the evaluator awards "P".   1.3.3 Reject Capability - The document claims [1] "T" and the   evaluator concurs.   1.3.4 Preclude Layer 2 Tunneling - The document [1] claims "T", and   in the absence of any detailed discussion of how this is   accomplished, in either [1] or [5], the evaluator awards "P".   1.3.5 Reauth on Demand -  The document [1] claims "T", and the   evaluator concurs.   1.3.6 Support for ACLs - The document [1] "T", and the evaluator   concurs.   1.3.7 State Reconciliation - The document [1] "T", and the evaluator   concurs.   1.3.8 Unsolicited Disconnect - The document [1] claims "T", and the   evaluator concurs.Mitton, et al.               Informational                     [Page 57]

RFC 3127            AAA Protocol Evaluation Process            June 2001   1.4 Accounting Requirements   1.4.1 Real Time Accounting -  The document [1] claims "T", and the   evaluator concurs.   1.4.2 Mandatory Compact Encoding - Note that the term "bloated" in   [3] is somewhat subjective.  The document [1] claims "T", and the   evaluator concurs.   1.4.3 Accounting Record Extensibility -  The document [1] claims "T",   and the evaluator concurs.   1.4.4 Batch Accounting - The protocol [2] [5] does not address how in   detail this feature might be accomplished.  The document [1] claims   "T", and the awards "P".   1.4.5 Guaranteed Delivery - Guaranteed delivery is provided by TCP.   The document [1] claims "T", and the evaluator concurs.   1.4.6 Accounting Timestamps - The document [1] claims "T", and the   evaluator concurs.   1.4.7 Dynamic Accounting - The document [1] claims "T", and the   evaluator concurs.   1.5 MOBILE IP Requirements   1.5.1 Encoding of MOBILE IP Registration Messages - The document [1]   claims "T", and the evaluator concurs.   1.5.2 Firewall Friendly - The document [1] claims "T", and the   evaluator concurs.   1.5.3 Allocation of Local Home Agent - The document [1] claims "T",   and the evaluator concurs.   2. Summary Discussion   It may appear, upon initial inspection, that the evaluator has not   lent a critical eye to the compliance assertions of the document [1].   First, this memo is a "PRO" brief, and as such reasonable benefit of   doubt is to be given in favor of the protocol submission.  Second,   there is a fundamental conceptual issue at play.  The COPS-PR model   provides a sufficient set of basic operations and commands, a   stateful model, the ability for either "peer" to initiate certain   kinds of requests, as well as an extensible command set, to be able   to support a wide variety of network and resource management   protocols.  The details of protocol specific messages is left toMitton, et al.               Informational                     [Page 58]

RFC 3127            AAA Protocol Evaluation Process            June 2001   Policy Information Base (PIB) data objects.  Since no AAA PIB has   been written, the evacuator can only (optimistically) assess the   inherent capabilities of the base protocol to accomplish the intended   requirements of [3], given a reasonable set of assumptions about what   an AAA PIB might look like.   In some sense, this akin to asserting that a given algorithm can be   correctly implemented in a specific programming language, without   actually providing the code.   The PIB model used by COPS is a powerful and flexible model.  The   protocol document [5] spends a considerable amount of time   enumerating and describing the benefits of this data model, and   explaining its roots in Object Oriented (OO) design methodology.   Analogies are made to class inheritance and class containment, among   others.  It's always hard to say bad things about OO.   3. General Requirements   COPS-AAA would appear to meet (totally or partially) all of the   requirements of [3], at least as can be determined without the   benefit of an AAA PIB.   4. Summary Recommendation   Recommended with reservation.  Before final acceptance of COPS-AAA,   someone is going to have to write the AAA PIB and evaluate its   details.C.8 COPS CON Evaluation   Evaluation of COPS against the AAA Requirements   CON Evaluation   Evaluator - David Mitton   The Primary document discussed here is [COPSComp] and the arguments   therein based on the proposal [COPSAAA].   [COPSComp]"Comparison of COPS Against the AAA NA Requirements", Work   in Progress.   [COPSAAA] "COPS Usage for AAA", Work in Progress.   [EksteinProtoComp] "AAA Protocols: Comparison between RADIUS,   Diameter, and COPS", Work in Progress.Mitton, et al.               Informational                     [Page 59]

RFC 3127            AAA Protocol Evaluation Process            June 2001   References: (in order of relevancy)   [COPSBase]  Durham, D., Boyle, J., Cohen, R., Herzog, S., Rajan, R.               and A. Sastry, "The Common Open Policy Service Protocol",RFC 2748, January 2000.   [COPSFwork] Yavatkar, R., Pendarakis, D. and R. Guerin, "A Framework               for Policy-based Admission Control",RFC 2753, January               2000.   [COPSPR]"COPS Usage for Policy Provisioning", Work in Progress.   [COPSSPPI]"Structure of Policy Provisioning Information (SPPI)",               Work in Progress.   [COPSCMS]"COPS Over CMS", Work in Progress.   [COPSTLS]"COPS Over TLS", Work in Progress.   [COPSGSS]   "COPS Extension for GSS-API based Authentication               Support", Work in Progress.   Other COPS & RSVP RFCs & drafts not listed as not directly relevant.   Compliance: T==Total, P==Partial, F=FailedSection 1 - Per item discussion   Initial Note: [COPSComp] claims "unconditional compliance" with all   requirements.   1.1 General Requirements   1.1.1 Scalability - P (was T) The evaluator is concerned with   scalability of many always-on TCP connections to a server supporting   a lot of clients, particularly with the heartbeat messages.  The   claim that the request handle is "unbounded" sounds fishy.   1.1.2 Fail-over - P (was T) COPS gives an indication of peer failure,   and has mechanisms to restart state, but there seems to be a bias   toward a single state server.  COPS has decided that synchronizing   state between multiple hot servers is out of scope.   Because COPS uses TCP, it is at the mercy of the TCP timers of the   implementation which can be significant.  Connection timeout   reporting to the application may be delayed beyond the client   authentication timeouts.  Tuning the Keep-Alive message to a tighter   period will increase the session and system overhead.Mitton, et al.               Informational                     [Page 60]

RFC 3127            AAA Protocol Evaluation Process            June 2001   1.1.3 Mutual Authentication - P (was T) The explanation is sort of   for message object integrity.  It does not describe authentication   techniques.  The evaluator assumes that COPS peers would authenticate   each other at Client-Open time.  But cannot understand how this would   work if proxies are involved.   1.1.4 Transmission Level Security - T   1.1.5 Data Object Confidentiality - T  Seems almost a carbon copy of   the Diameter capabilities.  This evaluator echoes the high overhead   concerns of the Diameter evaluator for the CMS capability.  TLS is   not mentioned here, but is piled on later.   1.1.6 Data Object Integrity - T  See above.   1.1.7 Certificate Transport - T   1.1.8 Reliable AAA Transport - T (maybe P) COPS meets this   requirement as well as any other protocol we've evaluated.  That is   it does have one application level ACK.  Statements such as "TCP   provides guaranteed delivery" are incorrect.  COPS does attempt to   identify outages by using a keep-alive message between TCP peers.   1.1.9 Run over IPv4 - T   1.1.10 Run over IPv6 - T   1.1.11 Support Proxy and Routing Brokers - P (was T)  How client   types are supported forward is not well understood by this evaluator.   Does each client type require the Broker to make a different client   Open request to it's upstream servers?  What about routing brokers?   1.1.12 Auditability - P (was T)  (based on our interpretation as   non-repudiation, rather than the definition given in reqts) The   explanation of a History PIB is incomplete and therefore   inconclusive.   1.1.13 Shared Secret Not Required - T  Except this clause in   [COPSAAA] 6.2 page 14 "COPS MUST be capable of supporting TLS"   1.1.14 Ability to Carry Service Specific Attributes - P (was T)   a) COPS only allows a small number of unique objects to be added.      256 Object "classes" or types, with 256 subtypes or versions.      Client types are 16 bits long, where the high bit indicates      "enterprise" specific values.  But pertain to a COPS peer-Mitton, et al.               Informational                     [Page 61]

RFC 3127            AAA Protocol Evaluation Process            June 2001      connection session.  The client type seems to just identify the      information model for the message. eg. it will be fixed to one      value for AAA.   b) Service specific objects are not the same as Vendor Specific      Objects.  They pertain to objects within a client type.   c) The PIB model leads to a different model interoperability.      Because most vendor product differ in some way, each PIB will be      different, and sharing common provisioning profiles will be a      rather difficult mapping problem on the server.   d) It's not clear the different client types can be mixed or that      other objects definitions can be used from other defined client      types.  It's really unclear how the client type of a connection      propagates in a proxy situation.   1.2 Authentication Requirements   1.2.1 NAI Support - T  The requirement thatRFC 2459 (X.509 profiles)   be met presumes that Auth servers would not have a mapping or local   transformation.   1.2.2 CHAP Support - T  An Information Model is being invoked, which   I don't see really fleshed out anywhere.  [COPSAAA] does a bit of   handwaving and definitions but doesn't deliver much meat.   Nonetheless, this could be handled ala RADIUS.   1.2.3 EAP Support - P (was T)  Again with the non-existent   Information Model.  To do EAP, this evaluator thinks another Request   or Decision type is needed here to indicate to proxies that an   extended message exchange is in progress.   1.2.4 PAP/Clear-text Passwords - T   1.2.5 Reauthentication on demand - T   1.2.6 Authorization w/o Authentication - T   The comment "Please note: with existing algorithms, any authorization   scheme not based on prior authentication is meaningless" is   meaningless out of application context.   1.3 Authorization Requirements   1.3.1 Static and Dynamic IP Addr Assignment - TMitton, et al.               Informational                     [Page 62]

RFC 3127            AAA Protocol Evaluation Process            June 2001   1.3.2 RADIUS Gateway Capability - P (was T).  It would be interesting   to see RADIUS attributes wrapped in some COPS "Information Model".   1.3.3 Reject Capability - T   1.3.4 Preclude Layer 2 Tunneling - T   More work for the "Information Model" author!   1.3.5 Reauthorization on Demand - T   1.3.6 Support for Access Rules & Filters - P (was T)  Yet more work   for the "Information Model" author, including some design issues   which alluded the RADIUS and Diameter designers.  At least an attempt   was made in Diameter.  There is nothing here.   1.3.7 State Reconciliation - P (was T).  It is difficult for the   evaluator to understand how well the COPS mechanisms work in a   multi-administration situation, or in any proxy situation.  Multi-   server coordination, if allowed, seems to be lacking a description.   1.3.8 Unsolicited Disconnect - T   1.4 Accounting Requirements   1.4.1 Real Time Accounting - T   1.4.2 Mandatory Compact Encoding - T  This evaluator does not believe   that ADIF is a compact format.  But does believe that the Information   Model author can design a PIB with accounting statistics that will   satisfy this requirement.   1.4.3 Accounting Record Extensibility - P (was T)  By defining a   vendor/device specific PIB for additional elements.   1.4.4 Batch Accounting - P (was T)  Offered description does not seem   to match the requirement.   1.4.5 Guaranteed Delivery - P (was T)  TCP does NOT "guarantee   delivery", only application Acks can do that.  If these acks can be   generated similar to the description here, then this requirement is   met.Mitton, et al.               Informational                     [Page 63]

RFC 3127            AAA Protocol Evaluation Process            June 2001   1.4.6 Accounting Timestamps - T  Another item for the "Information   Model" author.   1.4.7 Dynamic Accounting - T  Event and interim accounting can be   supported.   1.5 MOBILE IP Requirements   1.5.1 Encoding of MOBILE IP Registration Messages - P (was T)  Yet   more work for the "Information Model" author.  Hope he can handle it.   1.5.2 Firewall Friendly - P (was T)  I guess.  Because it uses TCP   and can be identified by known connection port.  But there is an   issue with respect to the impact level of mixed COPS traffic coming   through a common firewall port.   1.5.3 Allocation of Local Home Agent - P (was T)  Just add another   element to that "Information Model" definition.   2. Summary Discussion   COPS was designed to do some things similar to what we want and be   somewhat flexible, but with a totally different set of assumptions on   how many clients and requests would be funneled through the   infrastructure and the acceptable overhead.  This evaluator is not   sure that it scales well to the fast evolving access market where   every product doesn't implement a small set of common features, but a   large set of overlapping ones.   3. General Requirements   COPS started out with small and easily met set of design goals for   RSVP and DiffServe, and is evolving as a new hammer to hit other   nails [COPSPR].  As COPS implementors get more operational   experience, it is interesting to see more reliability fixes/features   quickly get patched in.   Understanding COPS requires that you read a number RFCs and drafts   which do not readily integrate well together.  Each application of   COPS has spawned a number of drafts.  It's not clear if one wants to   or can implement a single COPS server that can service AAA and other   application clients.   The COPS authors seem to overly believe in the goodness of TCP, and   rely on it to solve all their transport problems, with concessions to   application keep-alive messages to probe the connection status and   sequence numbers to prevent replay attacks.  This evaluator believes   this type of approach may work for many networks but really doesn'tMitton, et al.               Informational                     [Page 64]

RFC 3127            AAA Protocol Evaluation Process            June 2001   scale well in larger configurations.  End-to-end application acks are   the only guaranteed delivery solution, particularly where distributed   state is involved.   COPS falls into an in between place on encoding.  It has small number   of simple data object blobs which are concatenated ala   RADIUS/Diameter TLVs to form a flexible message layout.  However,   they attempt to limit the number of objects by making them   arbitrarily complex ala SNMP MIBs, and defining yet another data   structuring language for these PIBs.  There is a lot of computer   science style grandstanding in [COPSAAA]Section 1.2, but no   translation into how a set of data objects can be used to meet these   wonderful features in operation.  (or even if we needed them) This   will be the crux of the interoperability issue.  RADIUS   implementations interoperate because they at least, understand a   common set of functional attributes from the RFCs.  And vendor extent   ions can be simply customized in as needed via dictionaries.  If PIB   definitions are needed for every piece and version of access   equipment, before you can use it, then the bar for ease of   configuration and use has been raised quite high.   Support for PIB definition and vendor extensions will be on the same   order as MIB integration in SNMP management products and put the   supposed complexity of Diameter to shame.   4. Summary Recommendation   COPS has a structure that could be made to serve as a AAA protocol,   perhaps by just copying the features of RADIUS and Diameter into it.   The author of [COPSAAA] and [COPSComp] has not done the whole job yet   and some of the missing pieces are vexing even for those already in   the field.   While some of the synergy with other COPS services is attractive,   this evaluator is concerned about the liabilities of combining AAA   services with the new emerging COPS applications in a single server   entity will introduce more complexity than needed and opportunities   to have progress pulled into other rat-holes. (eg. Policy Frameworks)Mitton, et al.               Informational                     [Page 65]

RFC 3127            AAA Protocol Evaluation Process            June 2001Appendix D - Meeting Notes   The minutes of the team meetings as recorded by various members.D.1  Minutes of 22-Jun-2000 Teleconference   Recorded by: Mark Stevens   Arguments for and against SNMP as an AAA protocol were given.  Stuart   Barkley gave a summary of the pro argument.  Mike St. Johns gave a   summary of the con argument.  Dave Nelson asked for "instructions to   the jury" in an effort to determine what evidence could and could not   be used in making decisions.   The AAA evaluation criteria is weak in some areas and in others it   appears to be written with what might be interpreted as undue   influence from the NASREQ working group.   Mike St. Johns offered that we must restrict ourselves to considering   only the evidence provided in the compliance documents and any   supporting documents to which they may refer.   In summary: AAA evaluation criteria document, AAA evaluation criteria   source documents, protocol response documents and reference   documents.   The question as to what the group should do with malformed   requirements came up.  The consensus seemed to be that we would use   the requirements as adjusted in our last meeting where the   requirements made no sense.   The floor was then given to Stuart Barkley for the pro SNMP argument.   Highlights:   *  In most areas the requirements are met by SNMP.   *  Confidentiality and Certificate transport mechanisms may be weak,      but workable.   *  With regard to Authentication, every technique can be supported      although support for PAP or cleartext passwords is weak.   *  With regard to Authorization, there is nothing in the requirements      that cannot be supported.   *  Accounting everything supported, although there is no specific      consideration for compact encoding.  SNMP not as bloated as ASCII      or XML based encoding schemes.  Requirement for compact encoding      weakly indicated in requirements anyway.  Server-specific      attributes needed, but compact encoding preclude w/o tradeoffs.Mitton, et al.               Informational                     [Page 66]

RFC 3127            AAA Protocol Evaluation Process            June 2001   *  With regard to mobile IP requirement, everything works well,      although firewall friendliness is a judgment call.   *  Proxy mechanisms of SNMPv3 mitigates problems w/ firewalls.   *  Scalability is ok.   *  Overall, meets most requirements and shortfalls are minor.   *  In some cases requirements seemed to expressed in a manner that      "stacks" the odds against SNMP.   *  SNMP is deployed everywhere already.   *  The protocol has a well-understood behavior despite the tedium of      MIB definition, so it has the advantage of not requiring the      creation of a new infrastructure.   *  AAA response document is silent on architecture and MIB      definition, but there is too much work to do at this stage of      evaluation.  Not having done the MIB definitions and architecture      is not a limitation of the protocol.   *  SNMP is a good candidate.   Mike St. Johns took the floor to give a summary of the con argument.   *  Neither the requirements, core documents nor response document      specify the mechanism of operation.   *  Liberties were taken in the assertion that the server to server      interaction requirements were met.   *  The scaling arguments are weak.   *  Fail-over arguments are weak.   *  Security aspects work well with the manager/server paradigm, but      not well in bidirectional interactions among peers.   *  The authentication requirements not understood by authors of the      response document.  *  SNMP is just data moving protocol.   *  Message formats not specified.   *  What is the method for supporting authentication? Storing the      information is handled, but what do the nodes do with it?   *  The protocol certainly shined in the area of meeting accounting      requirements.   *  Although SNMP could certainly play a role in the accounting space,      it is unusable in the areas of Authorization and Authentication.   *  The response document does not address how the problem will be      solved.   *  It does not address the scalability issues that may arise in the      transition from a manager-agent mode of operation to a client-      server model.   The group then examined each requirement against SNMP in a line-by-   line exercise.Mitton, et al.               Informational                     [Page 67]

RFC 3127            AAA Protocol Evaluation Process            June 2001D.2  Minutes of 27-Jun-2000 Teleconference   Attendees - All (Mike St. John, Dave Mitton, Dave Nelson, Mark   Stevens, Barney Wolff, Stuart Barkley, Steven Crain, Basavaraj Patil)   Minutes recorded by : Basavaraj Patil   Evaluation of RADIUS++ AAA Requirements   Pro : Mark Stevens   Con : Dave Nelson   -  Question raised on if all meetings held so far have been recorded.      Last week's meeting was recorded by Mark.  Previous meetings have      been recorded by Mike.  All of these minutes should be available      in the archive.   -  Dave Nelson mentioned that Pat Calhoun has responded on the AAA WG      mailing list to the changes made to the requirements document by      the evaluation team.  Pat's response includes arguments for      inclusion of some of the requirements that were deleted by the      eval team.   -  Mike concluded that we can reinstate these requirements after      reviewing Pat's comments in detail and the RFCs referenced.  The      intent is to take Pat's comments/document and review it between      now and next Thursday (July 6th) and integrate the comments based      on the findings at that time.   Voting Procedure for evaluation : No voting during the discussion.   All votes MUST be submitted to Mike by COB, June 28th, 00.   -  Dave Nelson's summary of the Con statement for RADIUS++.      Overview of the points on which the evaluator disagrees with the      compliance statement.      Conclusion from Dave : Not recommended (Details in the con      statement).      Q: Is it possible to use it for accounting?      A: Authentication and Authorization could be separated, but      Accounting is the weak link in this protocol and hence is not      suitable.   -  Mark Steven's summary of the Pro statement      Agreed with most of the observations made by Dave Nelson.  The      biggest thing going for it is that it has been running in this      environment for a while and it does meet most of the requirementsMitton, et al.               Informational                     [Page 68]

RFC 3127            AAA Protocol Evaluation Process            June 2001      in the document.  Transition will be easy and backwards      compatibility is a key plus point.   Point-by-point Discussion:   General (1.1):   1.1.1 Scalability   BW - There is no actual limit on the number of outstanding requests.   The protocol itself does not limit the number.   DN -Simultaneous requests is not the same as outstanding requests.   Discussion of workarounds that have been implemented to overcome this   problem.   1.1.2 Fail-over   DN - This is an application layer protocol and uses application level   time-outs to provide fail-over solutions.  Analogy and discussion on   the use of round-trip-timer in TCP.   Example of how robust a network can be based on a machine at MIT that   was decommissioned and a new one with the same name installed in the   network.   Discussion of environments where proxies for primary, secondary and   tertiaries exist and the possible effect of flooding messages in the   event of a fail-over detection.   1.1.3 Mutual Authentication   No Discussion.  Accepted as stated.   1.1.4 Transmission level security   This requirement was deleted from the list by the evaluation team.   It was deleted because it is an overgeneralization of Roam Ops.   DN - There is a concern regarding what this really means.  Referred   to what Pat is saying about this on the list and the need for it to   be reinstated.   Suggestion to change the tag in the requirements document to hop-by-   hop security.Mitton, et al.               Informational                     [Page 69]

RFC 3127            AAA Protocol Evaluation Process            June 2001   Does the Roamops group use transmission level security to imply hop-   by-hop security?   1.1.5 Data Object Confidentiality   Mike explained the concept of Cryptographic Message Syntax (CMS -RFC2630).  There are some issues regarding the use of CMS at an end   point.  Symmetric or Asymmetric keys can be used.   There does not seem to be a problem with the suggested usage of CMS   in RADIUS++.   1.1.6/7 Data Object Integrity/Certificate Transport   No discussion.  (I guess everyone concurs with the statement in the   compliance document and the reviewers comments).   1.1.8 Reliable AAA Transport   BW - Radius provides reliability at the application layer by doing   retransmissions.  So why is there a need for a reliable AAA transport   protocol?   - Is it packet loss that the protocol needs to be concerned about?   DN - This requirement is tied to the failover issue.  Explanation of   the negative impact of retransmissions in a network, especially in   the case of a web of proxies.   Conclusion is that this requirement deals with packet loss.   1.1.9/10 Run over IPv4/6   Running over IPv6 should be a trivial issue.   1.1.11 Support Proxy and Routing Brokers   -  Discussion on what this requirement means and analogy to DNS      servers in a network.   -  RADIUS can be extended to support this requirement and from the      compliance document this does not appear to be fully cooked yet.   1.1.12 Auditability   No DiscussionMitton, et al.               Informational                     [Page 70]

RFC 3127            AAA Protocol Evaluation Process            June 2001   1.1.13 Shared Secret Not Required   This seems to be a trivial issue to be addressed in RADIUS++.   1.1.14 Ability to carry Service Specific Attributes   No Discussion   Authentication Requirements:   1.2.1 NAI Support   Trivial - Total compliance.   1.2.2 CHAP Support   Comment : RADIUS support of CHAP could be better and the response   needs to be encrypted.   1.2.3/4 EAP/PAP   No Discussion   1.2.5 Reauthentication on Demand   DN - Document claims that the server can reauthenticate by issuing an   Access-challenge.  There is a change to the state machine and the   suggested solution is too simplistic.  Also backwards compatibility   would be an issue.   1.2.6 Authorization w/o Authentication   DN - This is trivial to fix, but this is not mentioned in the   compliance document.   Authorization Requirements:   1.3.1 Static and Dynamic IP Addr assignment   -  RADIUS does not rise to the demands of being a resource manager   -  RADIUS assigns an address and it stays assigned for the session.      There is no concept of leasing.   1.3.2 RADIUS Gateway Capability   This is a requirement written that is not applicable to RADIUS   itself.Mitton, et al.               Informational                     [Page 71]

RFC 3127            AAA Protocol Evaluation Process            June 2001   1.3.3/4/5/6/7/8   Call dropped.  Somebody else needs to fill in here.  (Mike ????)   Accounting Requirements:   1.4.1 Real time accounting   No dissent.  No discussion   1.4.2 Mandatory compact encoding   Comment made regarding ASN.1 and XML in this context   1.4.3 Accounting Record Extensibility   No discussion   1.4.4 Batch Accounting   No specific wording in the document to show how this can be done.   Basically it is real time accounting without the real time   constraint.   It may be a trivial issue.   1.4.5/6 Guaranteed Delivery/Accounting Timestamps   No Discussion   1.4.7 Dynamic Accounting   There is ongoing discussion in the AAA WG on this requirement.  The   RADIUS WG is also discussing this (comment).  The idea here is to be   able to send the equivalent of a phonecall in progress type of   messages.   Mobile IP Requirements:   1.5.1 Encoding of Mobile IP Reg. Messages   May be trivial.  Discussion on what this requirement really is.  Is   it just the ability to carry the reg. message as payload? Does the   AAA protocol have to delve into the reg. message and behave   differently.Mitton, et al.               Informational                     [Page 72]

RFC 3127            AAA Protocol Evaluation Process            June 2001   1.5.2 Firewall Friendly   No Discussion   1.5.3 Allocation of Local Home Agents   This concept needs to be clarified as the author writing the   compliance statement did not understand it either.   If you notice anything that I recorded here as something   misinterpreted, please feel free to make corrections.D.3  Minutes of 29-Jun-2000 Teleconference   Attendees: Mike St. John, Dave Mitton, Dave Nelson, Barney Wolff,   Stuart Barkley, Steven Crain, Basavaraj Patil.   Missing: Mark Stevens.   Minutes recorded by: Stuart Barkley   Evaluation of Diameter AAA Requirements   Advocates:   Pro: Basavaraj Patil   Con: Barney Wolff   Summary discussion:   PRO summary (Basavaraj Patil):      session based      lightweight base + extensions      has implementation experience      based upon radius      fixes specific problems with radius,      interoperates with radius      looks like requirements are written for diameter   CON summary (Barney Wolff):      meets most needs, designed with requirements in mind   issues:  scalability in small devices (strong crypto specifically)      failover (need guidance on failover recovery procedures)Mitton, et al.               Informational                     [Page 73]

RFC 3127            AAA Protocol Evaluation Process            June 2001      Data object confidentiality has been expressed as very important,      diameter glosses over it referring torfc2630, cost to run on NAS      device      ACL: filter style syntax seems inadequate      state reconciliation: difficult over global multiple      administrative domains      batch accounting: implementation doesn't meet intended need      firewall friendly: until firewalls support SCTP will be failure   summary very close   concerns:   size and complexity needs almost all extensions to actually support   needs separation of SCTP and data (as per IESG suggestion?)   application vs transport acks   Point-by-point Discussion:   General (1.1):   1.1.1 Scalability      Handles large number of requests      SCTP reduces proxy needs (how? what is justification for this      statement?)      Scalability in large   1.1.2 Fail-over      Recovery from SCTP failure needs discussion (Note to DM: Include      in final document considerations)   1.1.3 Mutual Authentication      No Discussion   1.1.4 Transmission level security      No DiscussionMitton, et al.               Informational                     [Page 74]

RFC 3127            AAA Protocol Evaluation Process            June 2001   1.1.5/6 Data Object Confidentiality/Data Object Integrity      Crypto in NAS      NAS needs knowledge of when to use crypto      One Time Passwords   1.1.7 Certificate Transport      No Discussion   1.1.8 Reliable AAA Transport      No Discussion   1.1.9/10 Run over IPv4/6      No Discussion   1.1.11 Support Proxy and Routing Brokers      No Discussion   1.1.12 Auditability      No Discussion   1.1.13 Shared Secret Not Required      No Discussion   1.1.14 Ability to carry Service Specific Attributes      No Discussion   Authentication Requirements:   1.2.1 NAI Support      No Discussion   1.2.2 CHAP Support      No Discussion   1.2.3/4 EAP/PAP      No DiscussionMitton, et al.               Informational                     [Page 75]

RFC 3127            AAA Protocol Evaluation Process            June 2001   1.2.5 Reauthentication on Demand      No Discussion   1.2.6 Authorization w/o Authentication      No Discussion   Authorization Requirements:   1.3.1 Static and Dynamic IP Addr assignment      No Discussion   1.3.2 RADIUS Gateway Capability      Protocol requirement or implementation/application requirement?      Which RADIUS versions are to be supported?  Which subset?   1.3.3 Reject Capability      No Discussion   1.3.4 Preclude L2TP      No Discussion   1.3.5 Reauthorize on demand      Raj to look at this again   1.3.6 Support for ACLs      Standardizes syntax not semantics.      Standardizes semantics in NASREQ extension, but is very weak   1.3.7 State reconciliation      Appears to be weak in that server must "query the world" to      restore its state      Just in time reconciliation      Simultaneous usage limitations      More discussion neededMitton, et al.               Informational                     [Page 76]

RFC 3127            AAA Protocol Evaluation Process            June 2001   1.3.8 Unsolicited disconnect      No Discussion   Accounting Requirements:   1.4.1 Real time accounting      No Discussion   1.4.2 Mandatory compact encoding      Is ADIF compact?      Is ADIF UTF-8 compatible?   1.4.3 Accounting Record Extensibility      No Discussion   1.4.4 Batch Accounting      Diameter okay for small batches.  Specification doesn't seem      suitable for large batch transfers (100,000+ records)   1.4.5 Guaranteed Delivery      No Discussion   1.4.6 Accounting Timestamps      No Discussion   1.4.7 Dynamic Accounting      No Discussion   Mobile IP Requirements:   1.5.1 Encoding of Mobile IP Reg. Messages      Taken of faith   1.5.2 Firewall Friendly      Issues with SCTP being supported initially through firewallsMitton, et al.               Informational                     [Page 77]

RFC 3127            AAA Protocol Evaluation Process            June 2001   1.5.3 Allocation of Local Home Agents      Still lack of understanding of the AAA protocol requirements here      (versus just being a roaming attribute)   Overall summary:   Diameter seems to meet most requirements and is a likely candidate to   support AAA requirements.   Other matters:   Votes on Diameter should be in by Sunday evening.  Same format as   before.  Mike will tally up as both majority and average votes.   Should different requirements have different weight?   Possibility of SNMP reconsideration as per ADs?  To close off our   task in timeframe allocated, should not reopen submissions or   discussions.  Could cause to drag on for long time causing us to miss   our July 15 date.   Possibility of needing a few extra days to finish report due to   editing and review needs of the group.  Mike to ask ADs to consider   slight time extension possibility.   "No discussion" means that the topic was mentioned but there we no   objections/issues raised on that requirement being met.   These are based upon my notes.  Please send any corrections to the   list.D.4  Minutes of 06-Jul-2000 Teleconference   Minutes of AAA-Team Telecon 7/6/00   By: Barney Wolff   Pro review of COPS - Dave Nelson      Likes the object model.      No apparent showstoppers.      Will resend review with typos corrected.Mitton, et al.               Informational                     [Page 78]

RFC 3127            AAA Protocol Evaluation Process            June 2001   Con review of COPS - Dave Mitton      Architecture is mostly there.      Strong dependency on info model, sceptical of object model.      Problem with info model in multi-vendor, multi-administration      environment.      How does server speak to multiple client flavors?      Will resend review with typos corrected.   Comment by Mike StJ "replace SNMP with COPS" - :) I think.   Per-Item discussion   1.1.1 Scalability - concern re always-on TCP.  Direction to DM - add   general issue of number of connections.   1.1.2 Failover - No hot backup, but true of all protocols.  (ie, no   explicit mention of server-server protocol that might keep a backup   server in sync so it could take over instantly.)   1.1.3 Mutual Authentication - perhaps relies on TLS.  Draft does not   otherwise support this.   1.1.8 Reliable AAA Transport - TCP + appl heartbeat.   1.1.11 Proxy & Routing Brokers - client-type interaction with proxy   is questionable.  (In later discussion, it appears client-type is a   field in the request, and perhaps all AAA is one type, so may not be   an issue.)   1.1.13 Shared secret not req'd - runs over TLS, no multiple levels of   security.   1.2.1 NAI Support - some uncertainty on the impact ofRFC 2459 (X.509   profiles) on this - may restrict NAI in some way?   1.2.3 EAP Support - multi-pass handshake needs work.   1.2.6 Authorization without Authentication - Mike comments the   requirement is broken.  BW comment (post-meeting) - the requirement   appears intended specifically to chastise RADIUS for requiring User-   Name and some sort of password in an Access-Request, even if it's   sent pre-connect, on receipt of DNIS, for example.  Sure it's silly,   but does it really matter whether an attribute is absent or filled   with "NONE"?  This was just nasty sniping at RADIUS on somebody's   part, imho.   1.3.2 RADIUS Gateway - skepticism was expressed.Mitton, et al.               Informational                     [Page 79]

RFC 3127            AAA Protocol Evaluation Process            June 2001   1.3.4 Preclude L2 Tunnels - too much handwaving.   1.3.6 Access Rules - lots of work needed.   1.3.7 State Reconciliation - multi-server coordination is an issue.   1.4.4 Batch Accounting - for small batches, perhaps.   1.4.5 Guaranteed Delivery - application acks are an area of mystery.   1.5.2 Firewall-Friendly - COPS like any Swiss-Army-Knife protocol   (SNMP) requires the firewall to look inside the packets, because   passing AAA may be allowed but not other protocol uses.  So it would   be a big help, for both COPS and SNMP, to define a different port for   its AAA application.D.5  Minutes of 11-Jul-2000 Teleconference   Present:  Mike, Bernard, Paul, Bert, Raj, Dave N., Dave M., Barney,   Stuart, Mark   Recorded By: Dave Nelson   Mike St. Johns set the ground rules.   An item by item review of the summary results was held.   1.1.1 Question as to why SNMP and RADIUS++ are "P"?  There are issues   regarding scaling of retries in a web of proxies (multi-layer proxy;   primary, secondary tertiary servers at each level).   1.1.2 No protocol did very well.  Similar issues as above, e.g. web   of proxies.  Recovery of state from a previously failed primary   server?   1.1.3 Question as to how serious is the need for this requirement?   May be some legitimate requirements from Mobile IP.  Is this   requirement an AAA-level issue?   1.1.4 Called hop-by-hop or transmission level?   1.1.5 Most protocols evaluated used CMS to meet this requirement.   Question as to applicability of CMS for NASes and other edge devices?   There is a requirement for object by object confidentiality.   consider three-party scenarios.Mitton, et al.               Informational                     [Page 80]

RFC 3127            AAA Protocol Evaluation Process            June 2001   1.1.6 Question as to why SNMP did not rate the same as for item   1.1.5?  The evaluation is based on what was contained in the   submission documents, rather than capabilities of the protocol   itself.  Too much hand waving.   1.1.7 No comments.   1.1.8 Question as to meaning of "reliable"?  Discussion of transport   protocols was deferred to later in the meeting.   1.1.9 No comments.   1.1.10 SNMP received "P" because of hand waving in the submission   documents.   1.1.11 SNMP received "F" because this section of the submission   document indicated "t.b.d.".  Diameter was the only protocol   submission to completely address this item.   1.1.12 We treated this requirement as "non-repudiation".  There is a   concern that digital signatures are computationally expensive and are   not globally available.  COPS has more work to do on this item.   1.1.13 Question that "no shared secrets" should be interpreted to   mean that an alternative key management mechanism is available?  We   treated this as meaning that application-layer security could be   turned off in deference to transport layer security.  There had been   discussion of the use of IKE in the AAA protocol.   1.1.14 No comments.   1.2.1 No comments.   1.2.2 No comments.   1.2.3 No comments.   1.2.4 Is there a need for a clear-text "password" for service such as   OTP, SecurID, et. al.?   It was noted that all plain passwords are   exposed in clear-text at the NAS or other edge device, which is no   more inherently trustworthy than any AAA server or proxy.   1.2.5 We distinguished event-driven reauthentication from timer-   driven (or lifetime-driven).  How is this requirement to be met in a   proxy environment?   1.2.6 We asserted that this requirement is an oxymoron.Mitton, et al.               Informational                     [Page 81]

RFC 3127            AAA Protocol Evaluation Process            June 2001   1.3.1 We had difficulty in determining what "static" meant, and from   which reference point it was measured.   1.3.2 We agreed that NAIs could be handled, possibly with some   restrictions.   1.3.3 No comment.   1.3.4 The SNMP submission documents contained significant hand   waving.   1.3.5 Similar comments as to item 1.2.5.  The question was raised as   to how the server knows when to send this request?   1.3.6 We found that the notation in Diameter was weak, and of a least   common denominator nature.  In general, there was concern about   achieving interoperability when the syntax was standardized but the   semantics were not.  This area needs further work.   1.3.7 Question as to how this requirement is achieved via proxies?   1.4.1 No comment.   1.4.2 No comment.   1.4.3 No comment.   1.4.4 There was significant skepticism regarding batch accounting as   part of the AAA protocol.  How large are the "batches"?  Should this   requirement be met using FTP or something similar?   1.4.5 No comment.   1.4.6 No comment.   1.4.7 No comment.   1.5.1 No comment.   1.5.2 There was some discussion of what constitutes firewall   friendly.  It was suggested that the firewall didn't want to look   into packets much past the application protocol address (e.g. UDP or   TCP port number).  Protocols such as SNMP and COPS that have usage   other than AAA are at a disadvantage, since the firewall must look   deep into the application PDU to determine the intended purpose of   the packet.  Diameter suffers from reliance of SCTP, which is not   widely deployed or widely recognized by firewalls.  Should firewallsMitton, et al.               Informational                     [Page 82]

RFC 3127            AAA Protocol Evaluation Process            June 2001   also be AAA proxy engines?  Has this issue anything to do with   interoperability with NAT?   1.5.3 We had some confusion as to what the requirement actually was.   Raj seemed to be able to explain it, but the rest of us had to take   it on faith.   A poll was taken on overall acceptability and effort for each of the   protocols submitted, for requirements conformance.   Each member indicated their evaluation in the form of (Acceptable,   Not-Acceptable) with qualifiers for (Accounting, or effort to change)   This information will be summarized in the final report.   A general wrap-up discussion was held.   It was considered important that as much of the thought processes and   rationales be placed in the final report as is feasible.  Mike St.   John will work with Dave Mitton on the ID.  We really need to meet   the IETF July 14 submission deadline, even if we have to issue an   update on the AAA WG mailing list.  All agreed that the process went   fairly well.  In future evaluations of this nature, it would be well   for the evaluators to follow the requirements documents closely, for   the submitters to create accurate and complete conformance documents,   and to allow a "re-spin" cycle to correct errors and omissions in the   requirements documents and conformance documents.   A discussion of the transport protocol was held.   The issue with transport is congestion control.  There has been a   problem with streams-oriented applications over TCP.  The IESG is   increasingly sensitive to this issue in new protocols.  It was noted   that AAA was a transaction-oriented application.  Other request-   response applications, such as DNS, seem to scale welt to Internet-   scale using simple application-level retries and UDP transport.  TCP   has problems with head-of-line blocking, especially when multiple   sessions are using a single TCP connection.  AAA typically will send   3 or 4 iterations and then indicate a failure to the upper layers.   It won't continue retransmissions in the face of congestion, like   TCP.  It was noted that bulk data transfer may not best be   implemented in the AAA protocol.  Concern was voiced that SCTP is not   a widely implemented protocol.  AAA will implement congestion control   by limiting the number of outstanding requests.  Some RADIUS   implementations send lots of traffic when they encounter   misconfigured shared secrets, but this is likely caused by a lack of   proper error recovery.  Diameter, as currently drafted, relies on   SCTP.  Can AAA run over UDP?  The IESG didn't say "no"; their issue   is addressing congestion control.Mitton, et al.               Informational                     [Page 83]

RFC 3127            AAA Protocol Evaluation Process            June 2001Full Copyright Statement   Copyright (C) The Internet Society (2001).  All Rights Reserved.   This document and translations of it may be copied and furnished to   others, and derivative works that comment on or otherwise explain it   or assist in its implementation may be prepared, copied, published   and distributed, in whole or in part, without restriction of any   kind, provided that the above copyright notice and this paragraph are   included on all such copies and derivative works.  However, this   document itself may not be modified in any way, such as by removing   the copyright notice or references to the Internet Society or other   Internet organizations, except as needed for the purpose of   developing Internet standards in which case the procedures for   copyrights defined in the Internet Standards process must be   followed, or as required to translate it into languages other than   English.   The limited permissions granted above are perpetual and will not be   revoked by the Internet Society or its successors or assigns.   This document and the information contained herein is provided on an   "AS IS" basis and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING   TASK FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING   BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION   HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF   MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.Acknowledgement   Funding for the RFC Editor function is currently provided by the   Internet Society.Mitton, et al.               Informational                     [Page 84]