Network Working Group J.P. Vasseur (Editor) Cisco Systems, Inc. IETF Internet Draft J.L. Le Roux (Editor) France Telecom Proposed Status: Standard Track Expires: July 2007 S. Yasukawa NTT S. Previdi P. Psenak Cisco Systems, Inc. Paul Mabey Comcast December 2006 IGP Routing Protocol Extensions for Discovery of Traffic Engineering Node Capabilities draft-ietf-ccamp-te-node-cap-04.txt Status of this Memo By submitting this Internet-Draft, each author represents that any applicable patent or other IPR claims of which he or she is aware have been or will be disclosed, and any of which he or she becomes aware will be disclosed, in accordance with Section 6 of BCP 79. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF), its areas, and its working groups. Note that other groups may also distribute working documents as Internet-Drafts. Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet- Drafts as reference material or to cite them other than as "work in progress." The list of current Internet-Drafts can be accessed at http://www.ietf.org/ietf/1id-abstracts.txt. The list of Internet-Draft Shadow Directories can be accessed at http://www.ietf.org/shadow.html. Vasseur, Le Roux, et al. [Page 1] Internet Draft draft-ietf-ccamp-te-node-cap-04.txt December 2006 Abstract It is highly desired in several cases, to take into account Traffic Engineering (TE) node capabilities during Multi Protocol Label Switching (MPLS) and Generalized MPLS (GMPLS) Traffic Engineered Label Switched Path (TE-LSP) selection, such as for instance the capability to act as a branch Label Switching Router (LSR) of a Point-To-MultiPoint (P2MP) LSP. This requires advertising these capabilities within the Interior Gateway Protocol (IGP). For that purpose, this document specifies Open Shortest Path First (OSPF) and Intermediate System-Intermediate System (IS-IS) traffic engineering extensions for the advertisement of control plane and data plane traffic engineering node capabilities. Conventions used in this document 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 RFC-2119. Table of Contents 1. Terminology.................................................3 2. Introduction................................................3 3. TE Node Capability Descriptor...............................4 3.1. Description.................................................4 3.2. Required Information........................................4 4. TE Node Capability Descriptor TLV formats...................5 4.1. OSPF TE Node Capability Descriptor TLV format...............5 4.2. IS-IS TE Node Capability Descriptor sub-TLV format..........6 5. Elements of procedure.......................................7 5.1. OSPF........................................................7 5.2. IS-IS.......................................................8 6. Backward compatibility......................................8 7. Security Considerations.....................................9 8. IANA considerations.........................................9 8.1. OSPF TLV....................................................9 8.2. ISIS sub-TLV................................................9 8.3. Capability Registry.........................................9 9. Acknowledgments............................................10 10. References.................................................10 10.1. Normative references.......................................10 10.2. Informative References.....................................11 11. Editors' Addresses.........................................11 12. Contributors' Addresses....................................11 13. Intellectual Property Statement............................12 Vasseur, Le Roux, et al. [Page 2] Internet Draft draft-ietf-ccamp-te-node-cap-04.txt December 2006 1. Terminology This document uses terminologies defined in [RFC3031], [RFC3209] and [RFC4461]. 2. Introduction Multi Protocol Label Switching-Traffic Engineering (MPLS-TE) routing ([RFC3784], [RFC3630], [OSPFv3-TE]) relies on extensions to link state Interior Gateway Protocols (IGP) ([IS-IS], [RFC2328], [RFC2740]) in order to advertise Traffic Engineering (TE) link information used for constraint based routing. Further Generalized MPLS (GMPLS) related routing extensions are defined in [RFC4205] and [RFC4203]. It is desired to complement these routing extensions in order to advertise TE node capabilities, in addition to TE link information. These TE node capabilities will be taken into account as constraints during path selection. Indeed, it is useful to advertise data plane TE node capabilities, such as the capability for a Label Switching Router (LSR) to be a branch LSR or a bud-LSR of a Point-To-MultiPoint (P2MP) Label Switched Path (LSP). These capabilities can then be taken into account as constraints when computing the route of TE LSPs. It is also useful to advertise control plane TE node capabilities such as the capability to support GMPLS signaling for a packet LSR, or the capability to support P2MP (Point to Multipoint) TE LSP signaling. This allows selecting a path that avoids nodes that do not support a given control plane feature, or triggering a mechanism to support such nodes on a path. Hence this facilitates backward compatibility. For that purpose, this document specifies IGP (OSPF and IS-IS) extensions in order to advertise data plane and control plane capabilities of a node. A new TLV is defined for OSPF, the TE Node Capability Descriptor TLV, to be carried within the Router Information LSA ([OSPF-CAP]). A new sub-TLV is defined for IS-IS, the TE Node Capability Descriptor sub-TLV, to be carried within the IS-IS Capability TLV ([ISIS-CAP]). Vasseur, Le Roux, et al. [Page 3] Internet Draft draft-ietf-ccamp-te-node-cap-04.txt December 2006 3. TE Node Capability Descriptor 3.1. Description LSRs in a network may have distinct control plane and data plane Traffic Engineering capabilities. The TE Node Capability Descriptor information defined in this document describes data and control plane capabilities of an LSR. Such information can be used during path computation so as to avoid nodes that do not support a given TE feature either in the control or data plane, or to trigger procedures to handle these nodes along the path (e.g, trigger LSP hierarchy to support a legacy transit LSR on a P2MP LSP (see [RSVP-P2MP])). 3.2. Required Information The TE Node Capability Descriptor contains a variable length set of bit flags, where each bit corresponds to a given TE node capability. Five TE Node Capabilities are defined in this document: - B bit: when set, this flag indicates that the LSR can act as a branch node on a P2MP LSP (see [RFC4461]); - E bit: when set, this flag indicates that the LSR can act as a bud LSR on a P2MP LSP, i.e. an LSR that is both transit and egress (see [RFC4461]). - M bit: when set, this flag indicates that the LSR supports MPLS-TE signaling ([RFC3209]); - G bit: when set this flag indicates that the LSR supports GMPLS signaling ([RFC3473]); - P bit: when set, this flag indicates that the LSR supports P2MP MPLS-TE signaling ([RSVP-P2MP]). Note that new capability bits may be added in the future if required. Vasseur, Le Roux, et al. [Page 4] Internet Draft draft-ietf-ccamp-te-node-cap-04.txt December 2006 4. TE Node Capability Descriptor TLV formats 4.1. OSPF TE Node Capability Descriptor TLV format The OSPF TE Node Capability Descriptor TLV is a variable length TLV that contains a series of bit flags, where each bit correspond to a TE node capability. The OSPF TE Node Capability Descriptor TLV is carried within an OSPF Router Information LSA which is defined in [OSPF-CAP]. The format of the OSPF TE Node Capability Descriptor TLV is the same as the TLV format used by the Traffic Engineering Extensions to OSPF [RFC3630]. That is, the TLV is composed of 2 octets for the type, 2 octets specifying the length of the value field and a value field. The OSPF TE Node Capability Descriptor TLV has the following format: TYPE To be assigned by IANA (suggested value =1). LENGTH Variable (multiple of 4). VALUE Array of units of 32 flags numbered from the most significant bit as bit zero, where each bit represents a TE node capability. The following bits are defined: Bit Capabilities 0 B bit: P2MP Branch Node capability: When set this indicates that the LSR can act as a branch node on a P2MP LSP [RFC4461]. 1 E bit: P2MP Bud-LSR capability: When set, this indicates that the LSR can act as a bud LSR on a P2MP LSP, i.e. an LSR that is both transit and egress [RFC4461]. 2 M bit: If set this indicates that the LSR supports MPLS-TE signaling ([RFC3209]). 3 G bit: If set this indicates that the LSR supports GMPLS signaling ([RFC3473]). 4 P bit: If set this indicates that the LSR supports P2MP MPLS-TE signaling ([RSVP-P2MP]). 5-31 Reserved for future assignments by IANA. Vasseur, Le Roux, et al. [Page 5] Internet Draft draft-ietf-ccamp-te-node-cap-04.txt December 2006 4.2. IS-IS TE Node Capability Descriptor sub-TLV format The IS-IS TE Node Capability Descriptor sub-TLV is a variable length sub-TLV that contains a series of bit flags, where each bit correspond to a TE node capability. The IS-IS TE Node Capability Descriptor sub-TLV is carried within an IS-IS CAPABILITY TLV which is defined in [ISIS-CAP]. The format of the IS-IS TE Node Capability sub-TLV is the same as the TLV format used by the Traffic Engineering Extensions to IS-IS [RFC3784]. That is, the TLV is composed of 1 octet for the type, 1 octet specifying the TLV length and a value field. The IS-IS TE Node Capability Descriptor sub-TLV has the following format: TYPE: To be assigned by IANA (Suggested value =1) LENGTH: Variable VALUE: Array of units of 8 flags numbered from the most significant bit as bit zero, where each bit represents a TE node capability. The following bits are defined: Bit Capabilities 0 B bit: P2MP Branch Node capability: When set this indicates that the LSR can act as a branch node on a P2MP LSP [RFC4461]. 1 E bit: P2MP Bud-LSR capability: When set, this indicates that the LSR can act as a bud LSR on a P2MP LSP, i.e. an LSR that is both transit and egress [RFC4461]. 2 M bit: If set this indicates that the LSR supports MPLS-TE signaling ([RFC3209]). 3 G bit: If set this indicates that the LSR supports GMPLS signaling ([RFC3473]). 4 P bit: If set this indicates that the LSR supports P2MP MPLS-TE signaling ([RSVP-P2MP]). 5-7 Reserved for future assignments by IANA. Vasseur, Le Roux, et al. [Page 6] Internet Draft draft-ietf-ccamp-te-node-cap-04.txt December 2006 5. Elements of procedure 5.1. OSPF The TE Node Capability Descriptor TLV is advertised, within an OSPFv2 Router Information LSA (Opaque type of 4 and Opaque ID of 0) or an OSPFv3 Router Information LSA (function code of 12) which are defined in [OSPF-CAP]. As such, elements of procedure are inherited from those defined in [RFC2328], [RFC2740], and [OSPF-CAP]. The TE Node Capability Descriptor TLV advertises capabilities that may be taken into account as constraints during path selection. Hence its flooding scope is area-local, and it MUST be carried within OSPFv2 type 10 Router Information LSA (as defined in [RFC2370]) or an OSPFv3 Router Information LSA with the S1 bit set and the S2 bit cleared (as defined in [RFC2740]). A router MUST originate a new OSPF router information LSA whenever the content of the TE Node Capability Descriptor TLV changes or whenever required by the regular OSPF procedure (LSA refresh (every LSRefreshTime)). The TE Node Capability Descriptor TLV is OPTIONAL and MUST NOT appear more than once in an OSPF Router Information LSA. If a TE Node Capability Descriptor TLV appears more than once in an OSPF Router Information LSA, only the first occurrence MUST be processed and other MUST be ignored. When an OSPF LSA does not contain any TE Node capability Descriptor TLV, this means that the TE Capabilities of that LSR are unknown. Note that a change in any of these capabilities MAY trigger CSPF computation, but MUST NOT trigger normal SPF computation. Note also that TE node capabilities are expected to be fairly static. They may change as the result of configuration change, or software upgrade. This is expected not to appear more than once a day. Vasseur, Le Roux, et al. [Page 7] Internet Draft draft-ietf-ccamp-te-node-cap-04.txt December 2006 5.2. IS-IS The TE Node Capability sub-TLV is carried within an IS-IS CAPABILITY TLV defined in [IS-IS-CAP]. As such, elements of procedure are inherited from those defined in [IS-IS-CAP]. The TE Node Capability Descriptor sub-TLV advertises capabilities that may be taken into account as constraints during path selection. Hence its flooding is area-local, and MUST be carried within an IS-IS CAPABILITY TLV having the S flag cleared. An IS-IS router MUST originate a new IS-IS LSP whenever the content of any of the TE Node Capability sub-TLV changes or whenever required by the regular IS-IS procedure (LSP refresh). The TE Node Capability Descriptor sub-TLV is OPTIONAL and MUST NOT appear more than once in an ISIS Router Capability TLV. When an IS-IS LSP does not contain any TE Node capability Descriptor sub-TLV, this means that the TE Capabilities of that LSR are unknown. Note that a change in any of these capabilities MAY trigger CSPF computation, but MUST NOT trigger normal SPF computation. Note also that TE node capabilities are expected to be fairly static. They may change as the result of configuration change, or software upgrade. This is expected not to appear more than once a day. 6. Backward compatibility The TE Node Capability Descriptor TLVs defined in this document do not introduce any interoperability issue. For OSPF, a router not supporting the TE Node Capability Descriptor TLV will just silently ignore the TLV as specified in [OSPF-CAP]. For IS-IS a router not supporting the TE Node Capability Descriptor sub-TLV will just silently ignore the sub-TLV as specified in [IS-IS-CAP]. When the TE Node capability Descriptor TLV is absent, this means that the TE Capabilities of that LSR are unknown. The absence of a word of capability flags in OSPF or an octet of capability flags in IS-IS means that these capabilities are unknown. Vasseur, Le Roux, et al. [Page 8] Internet Draft draft-ietf-ccamp-te-node-cap-04.txt December 2006 7. Security Considerations This document specifies the content of the TE Node Capability Descriptor TLV in ISIS and OSPF, to be used for (G)MPLS-TE path computation. As this TLV is not used for SPF computation or normal routing, the extensions specified here have no direct effect on IP routing. Tampering with this TLV may have an effect on Traffic Engineering computation. Mechanisms defined to secure ISIS Link State PDUs [RFC3567], OSPF LSAs [RFC2154], and their TLVs, can be used to secure this TLV as well. 8. IANA considerations 8.1. OSPF TLV IANA is in charge of the assignment of TLV code points for the Router Information LSA defined in [OSPF-CAP]. IANA will assign a new codepoint for the TE Node Capability Descriptor TLV defined in this document and carried within the Router Information LSA (suggested value = 1). 8.2. ISIS sub-TLV IANA is in charge of the assignment of sub-TLV code points for the ISIS CAPABILITY TLV defined in [ISIS-CAP]. IANA will assign a new codepoint for the TE Node Capability Descriptor sub-TLV defined in this document, and carried within the ISIS CAPABILITY TLV (suggested value = 1). 8.3. Capability Registry IANA is requested to manage the space of capability bit flags carried within the OSPF and ISIS TE Node Capability Descriptor, numbering them in the usual IETF notation starting at zero, with the most significant bit as bit zero. A single registry must be defined for both protocols. New bit numbers may be allocated only by an IETF Consensus action. Each bit should be tracked with the following qualities: - Bit number - Defining RFC - Name of bit Five TE node capabilities are defined in this document and must be assigned by IANA. Here are the suggested values: 1 : B Bit = P2MP Branch LSR capability ([RFC4461]) 2 : E bit = P2MP Bud LSR capability ([RFC4461]) 3 : M bit = MPLS-TE support ([RFC3209]) 4 : G bit = GMPLS support (RFC3473)) 5 : P bit = P2MP RSVP-TE support ([RSVP-P2MP]) Vasseur, Le Roux, et al. [Page 9] Internet Draft draft-ietf-ccamp-te-node-cap-04.txt December 2006 9. Acknowledgments We would like to thank Benoit Fondeviole, Adrian Farrel, Dimitri Papadimitriou, Acee Lindem and David Ward for their useful comments and suggestions. We would also like to thank authors of [RFC4420] and [OSPF-CAP] from which some text of this document has been inspired. 10. References 10.1. Normative references [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. [RFC2328] Moy, J., "OSPF Version 2", RFC 2328, April 1998. [RFC2740] Coltun, R., Ferguson, D., and J. Moy, "OSPF for IPv6", RFC 2740, December 1999. [RFC2370] Coltun, R., "The OSPF Opaque LSA Option", RFC 2370, July 1998. [RFC4461] Yasukawa, S., et. al., "Signaling Requirements for Point to Multipoint Traffic Engineered MPLS LSPs", RFC4461, April 2006. [IS-IS] "Intermediate System to Intermediate System Intra-Domain Routing Exchange Protocol " ISO 10589. [RFC3630] Katz, D., Yeung, D., Kompella, K., "Traffic Engineering Extensions to OSPF Version 2", RFC 3630, September 2003. [RFC3784] Li, T., Smit, H., "IS-IS extensions for Traffic Engineering", RFC 3784, June 2004. [OSPF-CAP] Lindem, A., Shen, N., Aggarwal, R., Shaffer, S., Vasseur, J.P., "Extensions to OSPF for advertising Optional Router Capabilities", draft-ietf-ospf-cap, work in progress. [IS-IS-CAP] Vasseur, J.P. et al., "IS-IS extensions for advertising router information", draft-ietf-isis-caps, work in progress. [RFC3567] Li, T. and R. Atkinson, "Intermediate System to Intermediate System (IS-IS) Cryptographic Authentication", RFC 3567, July 2003. [RFC2154] Murphy, S., Badger, M., and B. Wellington, "OSPF with Digital Signatures", RFC 2154, June 1997. Vasseur, Le Roux, et al. [Page 10] Internet Draft draft-ietf-ccamp-te-node-cap-04.txt December 2006 [RFC3209] Awduche, D., et. al., "RSVP-TE: Extensions to RSVP for LSP tunnels", RFC 3209, December 2001. [RFC3473] Berger, L, et. al., "GMPLS Signaling RSVP-TE extensions", RFC 3473, January 2003. [RSVP-P2MP] Aggarwal, Papadimitriou, Yasukawa, et. al. "Extensions to RSVP-TE for point-to-multipoint TE LSPs", draft-ietf-mpls-rsvp-te- p2mp, work in progress. 10.2. Informative References [RFC4203] Kompella, K., Rekhter, Y., "OSPF extensions in support of Generalized Multi-protocol Label Switching", RFC4203, October 2005. [RFC4205] Kompella, K., Rekhter, Y., "IS-IS extensions in support of Generalized Multi-protocol Label Switching", RFC4205, October 2005. [RFC4420] Farrel, A., and al., "Encoding of attributes for MPLS LSPs establishment Using RSVP-TE", RFC4420, February 2006. 11. Editors' Addresses Jean-Philippe Vasseur Cisco Systems, Inc. 1414 Massachusetts Avenue Boxborough , MA - 01719 USA Email: jpv@cisco.com Jean-Louis Le Roux France Telecom 2, avenue Pierre-Marzin 22307 Lannion Cedex FRANCE Email: jeanlouis.leroux@orange-ftgroup.com 12. Contributors' Addresses Seisho Yasukawa NTT 3-9-11 Midori-cho, Musashino-shi, Tokyo 180-8585, Japan Email: s.yasukawa@hco.ntt.co.jp Stefano Previdi Cisco Systems, Inc Via Del Serafico 200 Roma, 00142 Italy Email: sprevidi@cisco.com Vasseur, Le Roux, et al. [Page 11] Internet Draft draft-ietf-ccamp-te-node-cap-04.txt December 2006 Peter Psenak Cisco Systems, Inc Pegasus Park DE Kleetlaan 6A Diegmen, 1831 BELGIUM Email: ppsenak@cisco.com Paul Mabbey Comcast USA 13. Intellectual Property Statement The IETF takes no position regarding the validity or scope of any Intellectual Property Rights 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; nor does it represent that it has made any independent effort to identify any such rights. Information on the procedures with respect to rights in RFC documents can be found in BCP 78 and BCP 79. Copies of IPR disclosures made to the IETF Secretariat 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 implementers or users of this specification can be obtained from the IETF on-line IPR repository at http://www.ietf.org/ipr. The IETF invites any interested party to bring to its attention any copyrights, patents or patent applications, or other proprietary rights that may cover technology that may be required to implement this standard. Please address the information to the IETF at ietf-ipr@ietf.org. Disclaimer of Validity This document and the information contained herein are provided on an "AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY, THE IETF TRUST AND THE INTERNET ENGINEERING TASK FORCE DISCLAIM 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. Vasseur, Le Roux, et al. [Page 12] Internet Draft draft-ietf-ccamp-te-node-cap-04.txt December 2006 Copyright Statement Copyright (C) The IETF Trust (2006). This document is subject to the rights, licenses and restrictions contained in BCP 78, and except as set forth therein, the authors retain all their rights. Vasseur, Le Roux, et al. [Page 13]