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Internet Engineering Task Force (IETF)                         A. FarrelRequest for Comments: 6123                            Old Dog ConsultingCategory: Historic                                         February 2011ISSN: 2070-1721Inclusion of Manageability Sections inPath Computation Element (PCE) Working Group DraftsAbstract   It has often been the case that manageability considerations have   been retrofitted to protocols after they have been specified,   standardized, implemented, or deployed.  This is sub-optimal.   Similarly, new protocols or protocol extensions are frequently   designed without due consideration of manageability requirements.   The Operations Area has developed "Guidelines for Considering   Operations and Management of New Protocols and Protocol Extensions"   (RFC 5706), and those guidelines have been adopted by the Path   Computation Element (PCE) Working Group.   Previously, the PCE Working Group used the recommendations contained   in this document to guide authors of Internet-Drafts on the contents   of "Manageability Considerations" sections in their work.  This   document is retained for historic reference.Status of This Memo   This document is not an Internet Standards Track specification; it is   published for the historical record.   This document defines a Historic Document for the Internet community.   This document is a product of the Internet Engineering Task Force   (IETF).  It represents the consensus of the IETF community.  It has   received public review and has been approved for publication by the   Internet Engineering Steering Group (IESG).  Not all documents   approved by the IESG are a candidate for any level of Internet   Standard; seeSection 2 of RFC 5741.   Information about the current status of this document, any errata,   and how to provide feedback on it may be obtained athttp://www.rfc-editor.org/info/rfc6123.Farrel                          Historic                        [Page 1]

RFC 6123          Manageability Sections in PCE Drafts     February 2011Copyright Notice   Copyright (c) 2011 IETF Trust and the persons identified as the   document authors.  All rights reserved.   This document is subject toBCP 78 and the IETF Trust's Legal   Provisions Relating to IETF Documents   (http://trustee.ietf.org/license-info) in effect on the date of   publication of this document.  Please review these documents   carefully, as they describe your rights and restrictions with respect   to this document.  Code Components extracted from this document must   include Simplified BSD License text as described in Section 4.e of   the Trust Legal Provisions and are provided without warranty as   described in the Simplified BSD License.1.  Introduction   This document is produced for historic reference.   When new protocols or protocol extensions are developed, it is often   the case that not enough consideration is given to the manageability   of the protocols or to the way in which they will be operated in the   network.  The result is that manageability considerations are only   understood once the protocols have been implemented and sometimes not   until after they have been deployed.   The resultant attempts to retrofit manageability mechanisms are not   always easy or architecturally pleasant.  Furthermore, it is possible   that certain protocol designs make manageability particularly hard to   achieve.   Recognizing that manageability is fundamental to the utility and   success of protocols designed within the IETF, and that simply   defining a MIB module does not necessarily provide adequate   manageability, this document was developed to define recommendations   for the inclusion of Manageability Considerations sections in all   Internet-Drafts produced within the PCE Working Group.  It was the   intention that meeting these recommendations would ensure that proper   consideration was given to the support of manageability at all stages   of the protocol development process from Requirements and   Architecture through Specification and Applicability.   It is clear that the presence of such a section in an Internet-Draft   does not guarantee that the protocol will be well-designed or   manageable.  However, the inclusion of this section will ensure that   the authors have the opportunity to consider the issues, and, by   reading the material in this document, they will gain some guidance.Farrel                          Historic                        [Page 2]

RFC 6123          Manageability Sections in PCE Drafts     February 2011   This document was developed within the PCE Working Group and was used   to help guide the authors and editors within the working group to   produce Manageability Considerations sections in the Internet-Drafts   and RFCs produced by the working group.   [RFC5706] presents general guidance from the IETF's Operations Area   for considering Operations and Management of new protocols and   protocol extensions.  It has been adopted by the PCE Working Group to   provide guidance to editors and authors within the working group, so   this document is no longer required.  However, the working group   considers that it will be useful to archive this document as Historic   for future reference.1.1.  Requirements Notation   This document is not a protocol specification.  The key words "MUST",   "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT",   "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be   interpreted as described in [RFC2119] in order that the contents of a   Manageability Considerations section can be clearly understood.1.2.  What Is Manageability?   In this context, "manageability" is used to refer to the interactions   between a network operator (a human or an application) and the   network components (hosts, routers, switches, applications, and   protocols) performed to ensure the correct operation of the network.   Manageability issues are often referred to under the collective   acronym, FCAPS [X.700], which stands for the following:   - Fault management   - Configuration   - Accounting   - Performance   - Security   Conventionally, Security is already covered an Internet-Draft in its   own Security Considerations section, and this document does not in   any way diminish the need for that section.  Indeed, as pointed out   inSection 6, a full consideration of other aspects of manageability   may increase the text that should be supplied in the Security   Considerations section.   The author of a Manageability Considerations section should certainly   consider all aspects of FCAPS.  The author should reflect on how the   manageability of a new protocol impacts the manageability and   operation of the entire network.  Specific optional subsections (seeFarrel                          Historic                        [Page 3]

RFC 6123          Manageability Sections in PCE Drafts     February 2011Section 2.3) should be added as necessary to describe features of   FCAPS that are pertinent but are not covered by the recommended   subsections.  More discussion of what manageability is and what may   be included in a Manageability Considerations section can be found in   [RFC5706].   As part of documenting the manageability considerations for a new   protocol or for protocol extensions, authors should consider that one   of the objectives of specifying protocols within the IETF is to   ensure interoperability of implementations.  This interoperability   extends to the manageability function so that it is an ideal that   there should be implementation independence between management   applications and managed entities.  This may be promoted by the use   of standardized management protocols and by the specification of   standard information models.   Note that, in some contexts, reference is made to the term   "management plane".  This is used to describe the exchange of   management messages through management protocols (often transported   by IP and by IP transport protocols) between management applications   and the managed entities such as network nodes.  The management plane   may use distinct addressing schemes, virtual links or tunnels, or a   physically separate management control network.  The management plane   should be seen as separate from, but possibly overlapping with, the   control plane, in which signaling and routing messages are exchanged,   and the forwarding plane (sometimes called the data plane or user   plane), in which user traffic is transported.2.  Presence and Placement of Manageability Considerations Sections   Note that examples of the sections described here can be found in the   documents listed inAppendix A.2.1.  Null Manageability Considerations Sections   In the event that there are no manageability requirements for an   Internet-Draft, the draft SHOULD still contain a Manageability   Considerations section.  The presence of this section indicates to   the reader that due consideration has been given to manageability and   that there are no (or no new) requirements.   In this case, the section SHOULD contain a simple statement such as   "There are no new manageability requirements introduced by this   document" and SHOULD briefly explain why that is the case with a   summary of manageability mechanisms that already exist.Farrel                          Historic                        [Page 4]

RFC 6123          Manageability Sections in PCE Drafts     February 2011   Note that a null Manageability Considerations section may take some   effort to compose.  It is important to demonstrate to the reader that   no additional manageability mechanisms are required, and it is often   hard to prove that something is not needed.  A null Manageability   Considerations section SHOULD NOT consist only of the simple   statement that there are no new manageability requirements.   If an Internet-Draft genuinely has no manageability impact, it should   be possible to construct a simple null Manageability Considerations   section that explains why this is the case.2.2.  Recommended Subsections   If the Manageability Considerations section is not null, it SHOULD   contain at least the following subsections.  Guidance on the content   of these subsections can be found inSection 3 of this document.   - Control of Function through Configuration and Policy   - Information and Data Models, e.g., MIB modules   - Liveness Detection and Monitoring   - Verifying Correct Operation   - Requirements on Other Protocols and Functional Components   - Impact on Network Operation   In the event that one or more of these subsections is not relevant,   it SHOULD still be present and SHOULD contain a simple statement   explaining why the subsection is not relevant.  That is, null   subsections are allowed, and each should be formed following the   advice inSection 2.1.2.3.  Optional Subsections   The list of subsections above is not intended to be prescriptively   limiting.  Other subsections can and SHOULD be added according to the   requirements of each individual Internet-Draft.  If a topic does not   fit comfortably into any of the subsections listed, the authors   should be relaxed about adding new subsections as necessary.2.4.  Placement of Manageability Considerations Sections   The Manageability Considerations section SHOULD be placed immediately   before the Security Considerations section in any Internet-Draft.Farrel                          Historic                        [Page 5]

RFC 6123          Manageability Sections in PCE Drafts     February 20113.  Guidance on the Content of Subsections   This section gives guidance on the information to be included in each   of the recommended subsections listed above.  Note that, just as   other subsections may be included, so additional information MAY also   be included in these subsections.3.1.  Control of Function through Configuration and Policy   This subsection describes the functional elements that may be   controlled through configuration and/or policy.   For example, many protocol specifications include timers that are   used as part of the operation of the protocol.  These timers often   have default values suggested in the protocol specification and do   not need to be configurable.  However, it is often the case that the   protocol requires that the timers can be configured by the operator   to ensure specific behavior by the implementation.   Even if all configurable items have been described within the body of   the document, they SHOULD be identified in this subsection, but a   reference to another section of the document is sufficient if there   is a full description elsewhere.   Other protocol elements are amenable to control through the   application of local or network-wide policy.  It is not the intention   that this subsection should give details of policy implementation   since that is covered by more general policy framework specifications   such as [RFC3060] and [RFC3460].  Additionally, specific frameworks   for policy as applicable within protocol or functional architectures   are also normally covered in separate documents, for example,   [RFC5394].   However, this section SHOULD identify which protocol elements are   potentially subject to policy and should give guidance on the   application of policy for successful operation of the protocol.   Where this material is already described within the body of the   document, this subsection SHOULD still identify the issues and   reference the other sections of the document.3.2.  Information and Data Models   This subsection SHOULD describe the information and data models   necessary for the protocol or the protocol extensions.  This   includes, but is not necessarily limited to, the MIB modules   developed specifically for the protocol functions specified in the   document.Farrel                          Historic                        [Page 6]

RFC 6123          Manageability Sections in PCE Drafts     February 2011   Where new or extended MIB modules are recommended, it is helpful if   this section can give an overview of the items to be modeled by the   MIB modules.  This does not require an object-by-object description   of all of the information that needs to be modeled, but it could   explain the high-level "object groupings" (perhaps to the level of   suggesting the MIB tables) and certainly should explain the major   manageable entities.  For example, a protocol specification might   include separate roles for "sender" and "receiver" and might be   broken into a "session" and individual "transactions"; if so, this   section could list these functionalities as separate manageable   entities.   [RFC3444] may be useful in determining what information to include in   this section.   The description in this section can be by reference where other   documents already exist.   It should be noted that the significance of MIB modules may be   decreasing, but there is still a requirement to consider the managed   objects necessary for successful operation of the protocol or   protocol extensions.  This means that due consideration should be   given not only to what objects need to be managed but also to what   management model should be used.  There are now several options,   including the MIB/SNMP (Simple Network Management Protocol) model and   the Network Configuration Protocol (NETCONF) model, being developed   by the NETCONF Data Modeling Language (NETMOD) Working Group [YANG].3.3.  Liveness Detection and Monitoring   Liveness detection and monitoring apply both to the control plane and   the data plane.   Mechanisms for detecting faults in the control plane or for   monitoring its liveness are usually built into the control plane   protocols or inherited from underlying data plane or forwarding plane   protocols.  These mechanisms do not typically require additional   management capabilities but are essential features for the protocol   to be usable and manageable.  Therefore, this section SHOULD   highlight the mechanisms in the new protocol or protocol extensions   that are required in order to ensure liveness detection and   monitoring within the protocol.   Further, when a control plane fault is detected, there is often a   requirement to coordinate recovery action through management   applications or at least to record the fact in an event log.  This   section SHOULD identify the management actions expected when the   protocol detects a control plane fault.Farrel                          Historic                        [Page 7]

RFC 6123          Manageability Sections in PCE Drafts     February 2011   Where the protocol is responsible for establishing data or user plane   connectivity, liveness detection and monitoring usually need to be   achieved through other mechanisms.  In some cases, these mechanisms   already exist within other protocols responsible for maintaining   lower layer connectivity, but it will often be the case that new   procedures are required so that failures in the data path can be   detected and reported rapidly, allowing remedial action to be taken.   This section SHOULD refer to other mechanisms that are assumed to   provide monitoring of data plane liveness and SHOULD identify   requirements for new mechanisms as appropriate.   This section SHOULD describe the need for liveness and detection   monitoring, SHOULD highlight existing tools, SHOULD identify   requirements and specifications for new tools (as appropriate for the   level of the document being written), and SHOULD describe the   coordination of tools with each other, with management applications,   and with the base protocol being specified.3.4.  Verifying Correct Operation   An important function that Operations and Management (OAM) can   provide is a toolset for verifying the correct operation of a   protocol.  To some extent, this may be achieved through access to   information and data models that report the status of the protocol   and the state installed on network devices.  However, it may also be   valuable to provide techniques for testing the effect that the   protocol has had on the network by sending data through the network   and observing its behavior.   Thus, this section SHOULD include details of how the correct   operation of the protocols described by the Internet-Draft can be   tested, and, in as far as the Internet-Draft impacts on the operation   of the network, this section SHOULD include a discussion about how   the correct end-to-end operation of the network can be tested and how   the correct data or forwarding plane function of each network element   can be verified.   There may be some overlap between this section and that describing   liveness detection and monitoring since the same tools may be used in   some cases.3.5.  Requirements on Other Protocols and Functional Components   The text in this section SHOULD describe the requirements that the   new protocol puts on other protocols and functional components as   well as requirements from other protocols that have been consideredFarrel                          Historic                        [Page 8]

RFC 6123          Manageability Sections in PCE Drafts     February 2011   in designing the new protocol.  This is pertinent to manageability   because those other protocols may already be deployed and operational   and because those other protocols also need to be managed.   It is not appropriate to consider the interaction between the new   protocol and all other protocols in this section, but it is important   to identify the specific interactions that are assumed for the   correct functioning of the new protocol or protocol extensions.3.6.  Impact on Network Operation   The introduction of a new protocol or extensions to an existing   protocol may have an impact on the operation of existing networks.   This section SHOULD outline such impacts (which may be positive),   including scaling concerns and interactions with other protocols.   For example, a new protocol that doubles the number of active,   reachable addresses in use within a network might need to be   considered in the light of the impact on the scalability of the IGPs   operating within the network.   A very important feature that SHOULD be addressed in this section is   backward compatibility.  If protocol extensions are being introduced,   what impact will this have on a network that has an earlier version   of the protocol deployed? Will it be necessary to upgrade all nodes   in the network? Can the protocol versions operate side by side? Can   the new version of the protocol be tunneled through the old version?   Can existing services be migrated without causing a traffic hit or is   a "maintenance period" required to perform the upgrade? What are the   configuration implications for the new and old protocol variants?   Where a new protocol is introduced, issues similar to backward   compatibility may exist and SHOULD be described.  How is migration   from an old protocol to the new protocol achieved? Do existing   protocols need to be interfaced to the new protocol?3.7.  Other Considerations   Anything that is not covered in one of the recommended subsections   described above but is needed to understand the manageability   situation SHOULD be covered in an additional section.  This may be a   catch-all section named "Other Considerations" or may be one or more   additional optional sections as described inSection 2.3.Farrel                          Historic                        [Page 9]

RFC 6123          Manageability Sections in PCE Drafts     February 20114.  IANA Considerations   This document does not introduce any new codepoints or name spaces   for registration with IANA.  It makes no request to IANA for action.   Internet-Drafts SHOULD NOT introduce new codepoints, name spaces, or   requests for IANA action within the Manageability Considerations   section.5.  Manageability Considerations   This document defines Manageability Considerations sections   recommended for inclusion in all PCE Working Group Internet-Drafts.   As such, the whole document is relevant to manageability.   Note that the impact of the application of this document to Internet-   Drafts produced within the PCE Working Group should be that PCE   protocols and associated protocols are designed and extended with   manageability in mind.  This should result in more robust and more   easily deployed protocols.   However, since this document does not describe any specific protocol,   protocol extensions, or protocol usage, no manageability   considerations need to be discussed here.   (This is an example of a null Manageability Considerations section).6.  Security Considerations   This document is Historic and describes the format and content of   Internet-Drafts.  As such, it introduces no new security concerns.   However, there is a clear overlap between security, operations, and   management.  The manageability aspects of security SHOULD be covered   within the mandatory Security Considerations of each Internet-Draft.   New security considerations introduced by the Manageability   Considerations section MUST be covered in the Security Considerations   section.   Note that fully designing a protocol before it is implemented   (including designing the manageability aspects) is likely to result   in a more robust protocol.  That is a benefit to network security.   Retrofitting manageability to a protocol can make the protocol more   vulnerable to security attacks, including attacks through the new   manageability facilities.  Therefore, the use of this document is   RECOMMENDED in order to help ensure the security of all protocols to   which it is applied.Farrel                          Historic                       [Page 10]

RFC 6123          Manageability Sections in PCE Drafts     February 20117.  Acknowledgements   This document is based on earlier work exploring the need for   Manageability Considerations sections in all Internet-Drafts produced   within the Routing Area of the IETF.  That document was produced by   Avri Doria and Loa Andersson working with the current author.  Their   input was both sensible and constructive.   Peka Savola provided valuable feedback on an early versions of the   original document.  Thanks to Bert Wijnen, Dan Romascanu, David   Harrington, Lou Berger, Spender Dawkins, Tom Petch, Matthew Meyer,   Dimitri Papdimitriou, Stewart Bryant, and Jamal Hadi Salim for their   comments.   Thanks to the PCE Working Group for adopting the ideas contained in   this document and for including Manageability Considerations sections   in their Internet-Drafts and RFCs.8.  References8.1.  Normative References   [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate             Requirement Levels",BCP 14,RFC 2119, March 1997.8.2.  Informative References   [RFC3060] Moore, B., Ellesson, E., Strassner, J., and A. Westerinen,             "Policy Core Information Model -- Version 1 Specification",RFC 3060, February 2001.   [RFC3460] Moore, B., Ed., "Policy Core Information Model (PCIM)             Extensions",RFC 3460, January 2003.   [RFC3444] Pras, A. and J. Schoenwaelder, "On the Difference between             Information Models and Data Models",RFC 3444, January             2003.   [RFC5394] Bryskin, I., Papadimitriou, D., Berger, L., and J. Ash,             "Policy-Enabled Path Computation Framework",RFC 5394,             December 2008.   [RFC5706] Harrington, D., "Guidelines for Considering Operations and             Management of New Protocols and Protocol Extensions",RFC5706, November 2009.   [X.700]   CCITT Recommendation X.700 (1992), Management framework for             Open Systems Interconnection (OSI) for CCITT applications.Farrel                          Historic                       [Page 11]

RFC 6123          Manageability Sections in PCE Drafts     February 2011   [YANG]    Bjorklund, M., Ed., "YANG - A Data Modeling Language for             the Network Configuration Protocol (NETCONF)",RFC 6020,             October 2010.Farrel                          Historic                       [Page 12]

RFC 6123          Manageability Sections in PCE Drafts     February 2011Appendix A.  Example Manageability Considerations Sections   Readers are referred to the following documents for example   Manageability Considerations sections that received positive comments   during IESG review:   Farrel, A., Vasseur, J.-P., and J. Ash, "A Path Computation Element   (PCE)-Based Architecture",RFC 4655, August 2006.   Le Roux, J., Ed., "Requirements for Path Computation Element (PCE)   Discovery",RFC 4674, October 2006.   Le Roux, JL., Ed., Vasseur, JP., Ed., Ikejiri, Y., and R. Zhang,   "OSPF Protocol Extensions for Path Computation Element (PCE)   Discovery",RFC 5088, January 2008.   Vasseur, JP., Ed., and JL. Le Roux, Ed., "Path Computation Element   (PCE) Communication Protocol (PCEP)",RFC 5440, March 2009.   Bradford, R., Ed., Vasseur, JP., and A. Farrel, "Preserving Topology   Confidentiality in Inter-Domain Path Computation Using a Path-Key-   Based Mechanism",RFC 5520, April 2009.   Oki, E., Takeda, T., Le Roux, JL., and A. Farrel, "Framework for PCE-   Based Inter-Layer MPLS and GMPLS Traffic Engineering",RFC 5623,   September 2009.Author's Address   Adrian Farrel   Old Dog Consulting   EMail: adrian@olddog.co.ukFarrel                          Historic                       [Page 13]