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Network Working Group                                            D. KatzRequest for Comments: 3630                                   K. KompellaUpdates:2370                                           Juniper NetworksCategory: Standards Track                                       D. Yeung                                                        Procket Networks                                                          September 2003Traffic Engineering (TE) Extensions to OSPF Version 2Status of this Memo   This document specifies an Internet standards track protocol for the   Internet community, and requests discussion and suggestions for   improvements.  Please refer to the current edition of the "Internet   Official Protocol Standards" (STD 1) for the standardization state   and status of this protocol.  Distribution of this memo is unlimited.Copyright Notice   Copyright (C) The Internet Society (2003).  All Rights Reserved.Abstract   This document describes extensions to the OSPF protocol version 2 to   support intra-area Traffic Engineering (TE), using Opaque Link State   Advertisements.1.  Introduction   This document specifies a method of adding traffic engineering   capabilities to OSPF Version 2 [1].  The architecture of traffic   engineering is described in [5].  The semantic content of the   extensions is essentially identical to the corresponding extensions   to IS-IS [6].  It is expected that the traffic engineering extensions   to OSPF will continue to mirror those in IS-IS.   The extensions provide a way of describing the traffic engineering   topology (including bandwidth and administrative constraints) and   distributing this information within a given OSPF area.  This   topology does not necessarily match the regular routed topology,   though this proposal depends on Network LSAs to describe multi-access   links.  This document purposely does not say how the mechanisms   described here can be used for traffic engineering across multiple   OSPF areas; that task is left to future documents.  Furthermore, no   changes have been made to the operation of OSPFv2 flooding; inKatz, et al.                Standards Track                     [Page 1]

RFC 3630            TE Extensions to OSPF Version 2       September 2003   particular, if non-TE capable nodes exist in the topology, they MUST   flood TE LSAs as any other type 10 (area-local scope) Opaque LSAs   (see [3]).1.1.  Applicability   Many of the extensions specified in this document are in response to   the requirements stated in [5], and thus are referred to as "traffic   engineering extensions", and are also commonly associated with MPLS   Traffic Engineering.  A more accurate (albeit bland) designation is   "extended link attributes", as the proposal is to simply add more   attributes to links in OSPF advertisements.   The information made available by these extensions can be used to   build an extended link state database just as router LSAs are used to   build a "regular" link state database; the difference is that the   extended link state database (referred to below as the traffic   engineering database) has additional link attributes.  Uses of the   traffic engineering database include:      o  monitoring the extended link attributes;      o  local constraint-based source routing; and      o  global traffic engineering.   For example, an OSPF-speaking device can participate in an OSPF area,   build a traffic engineering database, and thereby report on the   reservation state of links in that area.   In "local constraint-based source routing", a router R can compute a   path from a source node A to a destination node B; typically, A is R   itself, and B is specified by a "router address" (see below).  This   path may be subject to various constraints on the attributes of the   links and nodes that the path traverses, e.g., use green links that   have unreserved bandwidth of at least 10Mbps.  This path could then   be used to carry some subset of the traffic from A to B, forming a   simple but effective means of traffic engineering.  How the subset of   traffic is determined, and how the path is instantiated, is beyond   the scope of this document; suffice it to say that one means of   defining the subset of traffic is "those packets whose IP   destinations were learned from B", and one means of instantiating   paths is using MPLS tunnels.  As an aside, note that constraint-based   routing can be NP-hard, or even unsolvable, depending on the nature   of the attributes and constraints, and thus many implementations will   use heuristics.  Consequently, we don't attempt to sketch an   algorithm here.Katz, et al.                Standards Track                     [Page 2]

RFC 3630            TE Extensions to OSPF Version 2       September 2003   Finally, for "global traffic engineering", a device can build a   traffic engineering database, input a traffic matrix and an   optimization function, crunch on the information, and thus compute   optimal or near-optimal routing for the entire network.  The device   can subsequently monitor the traffic engineering topology and react   to changes by recomputing the optimal routes.1.2.  Limitations   As mentioned above, this document specifies extensions and procedures   for intra-area distribution of Traffic Engineering information.   Methods for inter-area and inter-AS (Autonomous System) distribution   are not discussed here.   The extensions specified in this document capture the reservation   state of point-to-point links.  The reservation state of multi-access   links may not be accurately reflected, except in the special case in   which there are only two devices in the multi-access subnetwork.   Operation over multi-access networks with more than two devices is   not specifically prohibited.  A more accurate description of the   reservation state of multi-access networks is for further study.   This document also does not support unnumbered links.  This   deficiency will be addressed in future documents; see also [7] and   [8].1.3.  Conventions   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 inBCP 14,RFC 2119 [2].2.  LSA Format2.1.  LSA type   This extension makes use of the Opaque LSA [3].   Three types of Opaque LSAs exist, each of which has a different   flooding scope.  This proposal uses only Type 10 LSAs, which have an   area flooding scope.   One new LSA is defined, the Traffic Engineering LSA.  This LSA   describes routers, point-to-point links, and connections to multi-   access networks (similar to a Router LSA).  For traffic engineering   purposes, the existing Network LSA is sufficient for describing   multi-access links, so no additional LSA is defined for this purpose.Katz, et al.                Standards Track                     [Page 3]

RFC 3630            TE Extensions to OSPF Version 2       September 20032.2.  LSA ID   The LSA ID of an Opaque LSA is defined as having eight bits of type   data and 24 bits of type-specific data.  The Traffic Engineering LSA   uses type 1.  The remaining 24 bits are the Instance field, as   follows:       0                   1                   2                   3       0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+      |       1       |                   Instance                    |      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+   The Instance field is an arbitrary value used to maintain multiple   Traffic Engineering LSAs.  A maximum of 16777216 Traffic Engineering   LSAs may be sourced by a single system.  The LSA ID has no   topological significance.2.3.  LSA Format Overview2.3.1.  LSA Header   The Traffic Engineering LSA starts with the standard LSA header:       0                   1                   2                   3       0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+      |            LS age             |    Options    |      10       |      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+      |       1       |                   Instance                    |      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+      |                     Advertising Router                        |      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+      |                     LS sequence number                        |      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+      |         LS checksum           |             Length            |      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+Katz, et al.                Standards Track                     [Page 4]

RFC 3630            TE Extensions to OSPF Version 2       September 20032.3.2.  TLV Header   The LSA payload consists of one or more nested Type/Length/Value   (TLV) triplets for extensibility.  The format of each TLV is:       0                   1                   2                   3       0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+      |              Type             |             Length            |      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+      |                            Value...                           |      .                                                               .      .                                                               .      .                                                               .      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+   The Length field defines the length of the value portion in octets   (thus a TLV with no value portion would have a length of zero).  The   TLV is padded to four-octet alignment; padding is not included in the   length field (so a three octet value would have a length of three,   but the total size of the TLV would be eight octets).  Nested TLVs   are also 32-bit aligned.  Unrecognized types are ignored.   This memo defines Types 1 and 2.  See the IANA Considerations section   for allocation of new Types.2.4.  LSA payload details   An LSA contains one top-level TLV.   There are two top-level TLVs defined:      1 - Router Address      2 - Link2.4.1.  Router Address TLV   The Router Address TLV specifies a stable IP address of the   advertising router that is always reachable if there is any   connectivity to it; this is typically implemented as a "loopback   address".  The key attribute is that the address does not become   unusable if an interface is down.  In other protocols, this is known   as the "router ID," but for obvious reasons this nomenclature is   avoided here.  If a router advertises BGP routes with the BGP next   hop attribute set to the BGP router ID, then the Router Address   SHOULD be the same as the BGP router ID.Katz, et al.                Standards Track                     [Page 5]

RFC 3630            TE Extensions to OSPF Version 2       September 2003   If IS-IS is also active in the domain, this address can also be used   to compute the mapping between the OSPF and IS-IS topologies.  For   example, suppose a router R is advertising both IS-IS and OSPF   Traffic Engineering LSAs, and suppose further that some router S is   building a single Traffic Engineering Database (TED) based on both   IS-IS and OSPF TE information.  R may then appear as two separate   nodes in S's TED.  However, if both the IS-IS and OSPF LSAs generated   by R contain the same Router Address, then S can determine that the   IS-IS TE LSA and the OSPF TE LSA from R are indeed from a single   router.   The router address TLV is type 1, has a length of 4, and a value that   is the four octet IP address.  It must appear in exactly one Traffic   Engineering LSA originated by a router.2.4.2.  Link TLV   The Link TLV describes a single link.  It is constructed of a set of   sub-TLVs.  There are no ordering requirements for the sub-TLVs.   Only one Link TLV shall be carried in each LSA, allowing for fine   granularity changes in topology.   The Link TLV is type 2, and the length is variable.   The following sub-TLVs of the Link TLV are defined:      1 - Link type (1 octet)      2 - Link ID (4 octets)      3 - Local interface IP address (4 octets)      4 - Remote interface IP address (4 octets)      5 - Traffic engineering metric (4 octets)      6 - Maximum bandwidth (4 octets)      7 - Maximum reservable bandwidth (4 octets)      8 - Unreserved bandwidth (32 octets)      9 - Administrative group (4 octets)   This memo defines sub-Types 1 through 9.  See the IANA Considerations   section for allocation of new sub-Types.   The Link Type and Link ID sub-TLVs are mandatory, i.e., must appear   exactly once.  All other sub-TLVs defined here may occur at most   once.  These restrictions need not apply to future sub-TLVs.   Unrecognized sub-TLVs are ignored.Katz, et al.                Standards Track                     [Page 6]

RFC 3630            TE Extensions to OSPF Version 2       September 2003   Various values below use the (32 bit) IEEE Floating Point format.   For quick reference, this format is as follows:       0                   1                   2                   3       0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+      |S|    Exponent   |                  Fraction                   |      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+   S is the sign, Exponent is the exponent base 2 in "excess 127"   notation, and Fraction is the mantissa - 1, with an implied binary   point in front of it.  Thus, the above represents the value:      (-1)**(S) * 2**(Exponent-127) * (1 + Fraction)   For more details, refer to [4].2.5.  Sub-TLV Details2.5.1.  Link Type   The Link Type sub-TLV defines the type of the link:      1 - Point-to-point      2 - Multi-access   The Link Type sub-TLV is TLV type 1, and is one octet in length.2.5.2.  Link ID   The Link ID sub-TLV identifies the other end of the link.  For   point-to-point links, this is the Router ID of the neighbor.  For   multi-access links, this is the interface address of the designated   router.  The Link ID is identical to the contents of the Link ID   field in the Router LSA for these link types.   The Link ID sub-TLV is TLV type 2, and is four octets in length.2.5.3.  Local Interface IP Address   The Local Interface IP Address sub-TLV specifies the IP address(es)   of the interface corresponding to this link.  If there are multiple   local addresses on the link, they are all listed in this sub-TLV.   The Local Interface IP Address sub-TLV is TLV type 3, and is 4N   octets in length, where N is the number of local addresses.Katz, et al.                Standards Track                     [Page 7]

RFC 3630            TE Extensions to OSPF Version 2       September 20032.5.4.  Remote Interface IP Address   The Remote Interface IP Address sub-TLV specifies the IP address(es)   of the neighbor's interface corresponding to this link.  This and the   local address are used to discern multiple parallel links between   systems.  If the Link Type of the link is Multi-access, the Remote   Interface IP Address is set to 0.0.0.0; alternatively, an   implementation MAY choose not to send this sub-TLV.   The Remote Interface IP Address sub-TLV is TLV type 4, and is 4N   octets in length, where N is the number of neighbor addresses.2.5.5.  Traffic Engineering Metric   The Traffic Engineering Metric sub-TLV specifies the link metric for   traffic engineering purposes.  This metric may be different than the   standard OSPF link metric.  Typically, this metric is assigned by a   network administrator.   The Traffic Engineering Metric sub-TLV is TLV type 5, and is four   octets in length.2.5.6.  Maximum Bandwidth   The Maximum Bandwidth sub-TLV specifies the maximum bandwidth that   can be used on this link, in this direction (from the system   originating the LSA to its neighbor), in IEEE floating point format.   This is the true link capacity.  The units are bytes per second.   The Maximum Bandwidth sub-TLV is TLV type 6, and is four octets in   length.2.5.7.  Maximum Reservable Bandwidth   The Maximum Reservable Bandwidth sub-TLV specifies the maximum   bandwidth that may be reserved on this link, in this direction, in   IEEE floating point format.  Note that this may be greater than the   maximum bandwidth (in which case the link may be oversubscribed).   This SHOULD be user-configurable; the default value should be the   Maximum Bandwidth.  The units are bytes per second.   The Maximum Reservable Bandwidth sub-TLV is TLV type 7, and is four   octets in length.Katz, et al.                Standards Track                     [Page 8]

RFC 3630            TE Extensions to OSPF Version 2       September 20032.5.8.  Unreserved Bandwidth   The Unreserved Bandwidth sub-TLV specifies the amount of bandwidth   not yet reserved at each of the eight priority levels in IEEE   floating point format.  The values correspond to the bandwidth that   can be reserved with a setup priority of 0 through 7, arranged in   increasing order with priority 0 occurring at the start of the sub-   TLV, and priority 7 at the end of the sub-TLV.  The initial values   (before any bandwidth is reserved) are all set to the Maximum   Reservable Bandwidth.  Each value will be less than or equal to the   Maximum Reservable Bandwidth.  The units are bytes per second.   The Unreserved Bandwidth sub-TLV is TLV type 8, and is 32 octets in   length.2.5.9.  Administrative Group   The Administrative Group sub-TLV contains a 4-octet bit mask assigned   by the network administrator.  Each set bit corresponds to one   administrative group assigned to the interface.  A link may belong to   multiple groups.   By convention, the least significant bit is referred to as 'group 0',   and the most significant bit is referred to as 'group 31'.   The Administrative Group is also called Resource Class/Color [5].   The Administrative Group sub-TLV is TLV type 9, and is four octets in   length.3.  Elements of Procedure   Routers shall originate Traffic Engineering LSAs whenever the LSA   contents change, and whenever otherwise required by OSPF (an LSA   refresh, for example).  Note that this does not mean that every   change must be flooded immediately; an implementation MAY set   thresholds (for example, a bandwidth change threshold) that trigger   immediate flooding, and initiate flooding of other changes after a   short time interval.  In any case, the origination of Traffic   Engineering LSAs SHOULD be rate-limited to at most one every   MinLSInterval [1].   Upon receipt of a changed Traffic Engineering LSA or Network LSA   (since these are used in traffic engineering calculations), the   router should update its traffic engineering database.  No Shortest   Path First (SPF) or other route calculations are necessary.Katz, et al.                Standards Track                     [Page 9]

RFC 3630            TE Extensions to OSPF Version 2       September 20034.  Compatibility Issues   There should be no interoperability issues with routers that do not   implement these extensions, as the Opaque LSAs will be silently   ignored.   The result of having routers that do not implement these extensions   is that the traffic engineering topology will be missing pieces.   However, if the topology is connected, TE paths can still be   calculated and ought to work.5.  Security Considerations   This document specifies the contents of Opaque LSAs in OSPFv2.  As   Opaque LSAs are not used for SPF computation or normal routing, the   extensions specified here have no affect on IP routing.  However,   tampering with TE LSAs may have an effect on traffic engineering   computations, and it is suggested that any mechanisms used for   securing the transmission of normal OSPF LSAs be applied equally to   all Opaque LSAs, including the TE LSAs specified here.   Note that the mechanisms in [1] and [9] apply to Opaque LSAs.  It is   suggested that any future mechanisms proposed to secure/authenticate   OSPFv2 LSA exchanges be made general enough to be used with Opaque   LSAs.6.  IANA Considerations   The top level Types in a TE LSA, as well as Types for sub-TLVs for   each top level Type, have been registered with IANA, except as noted.   Here are the guidelines (using terms defined in [10]) for the   assignment of top level Types in TE LSAs:   o  Types in the range 3-32767 are to be assigned via Standards      Action.   o  Types in the range 32768-32777 are for experimental use; these      will not be registered with IANA, and MUST NOT be mentioned by      RFCs.   o  Types in the range 32778-65535 are not to be assigned at this      time.  Before any assignments can be made in this range, there      MUST be a Standards Track RFC that specifies IANA Considerations      that covers the range being assigned.Katz, et al.                Standards Track                    [Page 10]

RFC 3630            TE Extensions to OSPF Version 2       September 2003   The guidelines for the assignment of types for sub-TLVs in a TE LSA   are as follows:   o  Types in the range 10-32767 are to be assigned via Standards      Action.   o  Types in the range 32768-32777 are for experimental use; these      will not be registered with IANA, and MUST NOT be mentioned by      RFCs.   o  Types in the range 32778-65535 are not to be assigned at this      time.  Before any assignments can be made in this range, there      MUST be a Standards Track RFC that specifies IANA Considerations      that covers the range being assigned.7.  Intellectual Property Rights Statement   The IETF takes no position regarding the validity or scope of any   intellectual property or other rights that might be claimed to   pertain to the implementation or use of the technology described in   this document or the extent to which any license under such rights   might or might not be available; neither does it represent that it   has made any effort to identify any such rights.  Information on the   IETF's procedures with respect to rights in standards-track and   standards-related documentation can be found inBCP-11.  Copies of   claims of rights made available for publication and any assurances of   licenses to be made available, or the result of an attempt made to   obtain a general license or permission for the use of such   proprietary rights by implementors or users of this specification can   be obtained from the IETF Secretariat.   The IETF invites any interested party to bring to its attention any   copyrights, patents or patent applications, or other proprietary   rights which may cover technology that may be required to practice   this standard.  Please address the information to the IETF Executive   Director.Katz, et al.                Standards Track                    [Page 11]

RFC 3630            TE Extensions to OSPF Version 2       September 20038.  References8.1.  Normative References   [1]  Moy, J., "OSPF Version 2", STD 54,RFC 2328, April 1998.   [2]  Bradner, S., "Key words for use in RFCs to Indicate Requirement        Levels",BCP 14,RFC 2119, March 1997.   [3]  Coltun, R., "The OSPF Opaque LSA Option",RFC 2370, July 1998.   [4]  IEEE, "IEEE Standard for Binary Floating-Point Arithmetic",        Standard 754-1985, 1985 (ISBN 1-5593-7653-8).8.2.  Informative References   [5]  Awduche, D., Malcolm, J., Agogbua, J., O'Dell, M. and J.        McManus, "Requirements for Traffic Engineering Over MPLS",RFC2702, September 1999.   [6]  Smit, H. and T. Li, "ISIS Extensions for Traffic Engineering",        work in progress.   [7]  Kompella, K. and Y. Rekhter, "Signalling Unnumbered Links in        Resource ReSerVation Protocol - Traffic Engineering (RSVP-TE)",RFC 3477, January 2003.   [8]  Kompella, K., Rekhter, Y. and A. Kullberg, "Signalling        Unnumbered Links in CR-LDP (Constraint-Routing Label        Distribution Protocol)",RFC 3480, February 2003.   [9]  Murphy, S., Badger, M. and B. Wellington, "OSPF with Digital        Signatures",RFC 2154, June 1997.   [10] Narten, T. and H. Alvestrand, "Guidelines for Writing an IANA        Considerations Section in RFCs",BCP 26,RFC 2434, October 1998.Katz, et al.                Standards Track                    [Page 12]

RFC 3630            TE Extensions to OSPF Version 2       September 20039.  Authors' Addresses   Dave Katz   Juniper Networks   1194 N. Mathilda Ave.   Sunnyvale, CA 94089 USA   Phone: +1 408 745 2000   EMail: dkatz@juniper.net   Derek M. Yeung   Procket Networks, Inc.   1100 Cadillac Court   Milpitas, CA 95035 USA   Phone: +1 408 635-7900   EMail: myeung@procket.com   Kireeti Kompella   Juniper Networks   1194 N. Mathilda Ave.   Sunnyvale, CA 94089 USA   Phone: +1 408 745 2000   EMail: kireeti@juniper.netKatz, et al.                Standards Track                    [Page 13]

RFC 3630            TE Extensions to OSPF Version 2       September 200310.  Full Copyright Statement   Copyright (C) The Internet Society (2003).  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 assignees.   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.Katz, et al.                Standards Track                    [Page 14]