Networking Working Group JP. Vasseur, Ed. Internet-Draft Cisco Systems, Inc Expires: December 22, 2006 Matthew. R. Meyer Global Crossing K. Kumaki KDDI Corporation Alberto. Tempia Bonda Telecom Italia June 20, 2006 A Link-Type sub-TLV to convey the number of Traffic Engineering Label Switch Paths signalled across a link draft-ietf-mpls-number-0-bw-te-lsps-02 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. This Internet-Draft will expire on December 22, 2006. Copyright Notice Copyright (C) The Internet Society (2006). Abstract Several Link-type sub-TLVs have been defined for OSPF and ISIS in the context of MPLS Traffic Engineering in order to advertise some link Vasseur, et al. Expires December 22, 2006 [Page 1] Internet-Draft draft-ietf-mpls-number-0-bw-te-lsps-02 June 2006 characteristics such as the available bandwidth, traffic engineering metric, administrative group and so on. There are various circumstances (for example in order to load balance unconstrained TE Label Switched Path (LSP) across a set of equal cost paths) where it would be useful to also advertise the number of unconstrained Traffic Engineering Label Switched Path(s) (TE LSP) signalled across a link. This document specifies a new Link-type Traffic Engineering sub-TLV used to advertise the number of unconstrained TE LSP(s) signalled across a link. Requirements Language 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 [RFC2119]. Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . . 3 3. Protocol extensions . . . . . . . . . . . . . . . . . . . . . . 4 3.1. IS-IS . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 3.2. OSPF . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 4. Elements of procedure . . . . . . . . . . . . . . . . . . . . . 5 5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 5 6. Security Considerations . . . . . . . . . . . . . . . . . . . . 5 7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 5 8. References . . . . . . . . . . . . . . . . . . . . . . . . . . 5 8.1. Normative References . . . . . . . . . . . . . . . . . . . 5 8.2. Informative References . . . . . . . . . . . . . . . . . . 6 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 7 Intellectual Property and Copyright Statements . . . . . . . . . . 8 Vasseur, et al. Expires December 22, 2006 [Page 2] Internet-Draft draft-ietf-mpls-number-0-bw-te-lsps-02 June 2006 1. Introduction A set of Link-type sub-TLVs have been defined for OSPF and ISIS (see [I-D.ietf-isis-te-bis] and [RFC3630]) in the context of MPLS Traffic Engineering in order to advertise various link characteristics such as the available bandwidth, traffic engineering metric, administrative group and so on. There are various circumstances (detailed below) where it would be useful to also advertise the number of unconstrained Traffic Engineering Label Switch Path(s) (TE LSP). It is not uncommon to deploy MPLS Traffic Engineering for the sake of fast recovery relying on a local protection recovery mechanism such as MPLS TE Fast Reroute (see [RFC4090]). In this case, a deployment model consists of deploying a full mesh of unconstrained TE LSPs between a set of LSRs and protect these TE LSPs with pre-established backup tunnels against link, SRLG and/or node failures. The traffic routed onto such unconstrained TE LSP simply follows the IGP shortest path but is protected with MPLS TE Fast Reroute. With MPLS Traffic Engineering a usual rerouting criteria is the discovery of a better path for a TE LSP where a better path is defined as a path with a lower cost according to a specific metric; other metric such that the percentage of reserved bandwidth or the number of hops can also be used. Unfortunately, for instance in the presence of ECMPs (Equal Cost Multi-Paths) in symmetrical networks when unconstrained TE LSP are used, such metrics are usually ineffective and may lead to poorly load balanced traffic. If the number of unconstrained TE LSPs traversing each link in the network is known, various algorithms can be designed so as to efficiently load balance the traffic carried onto such unconstrained TE LSPs. As currently defined in [RFC3630] and [I-D.ietf-isis-te-bis] the information related to the number of unconstrained TE LSP(s) is not available. This document specifies a new Link-type Traffic Engineering sub-TLV used to indicate the number of unconstrained TE LSP signalled across a link. Note that the specification of load balancing algorithms is outside of the scope of this document and merely listed for the sake of illustration of the motivation for gathering such information. Furthermore, the knowledge of the number of unconstrained TE LSPs signalled across each link can be used for other purposes (e.g. management, ...). 2. Terminology Vasseur, et al. Expires December 22, 2006 [Page 3] Internet-Draft draft-ietf-mpls-number-0-bw-te-lsps-02 June 2006 Terminology used in this document LSA: Link State Advertisement. LSP: Link State Packet. LSR: Label Switching Router. TE LSP: Traffic Engineering Label Switched Path. Unconstrained TE LSP: A TE LSP signalled with a bandwidth equal to 0. 3. Protocol extensions A new Sub-TLV named NB-O-BW-LSP is defined that specifies the number of unconstrained TE LSPs signalled across a link. 3.1. IS-IS The NB-0-BW-LSP sub-TLV is OPTIONAL and MUST appear at most once within the extended IS reachability TLV (type 22) specified in [I-D.ietf-isis-te-bis]. The IS-IS NB-0-BW-LSP sub-TLV format is defined below: Type (1 octet): To be assigned by IANA (suggested value = 19) Length (1 octet): 4 Value (4 octets): number of unconstrained TE LSP(s) signalled across the link. 3.2. OSPF The NB-0-BW-LSP sub-TLV is OPTIONAL and MUST appear at most once within the Link TLV (Type 2) that is itself carried within the Traffic Engineering LSA specified in [RFC3630]. The OSPF NB-0-BW-LSP sub-TLV format is defined below: Type (2 octets): To be assigned by IANA (suggested value = 19) Length (2 octets): 4 Value (4 octets): number of unconstrained TE LSP(s) signalled across the link. Vasseur, et al. Expires December 22, 2006 [Page 4] Internet-Draft draft-ietf-mpls-number-0-bw-te-lsps-02 June 2006 4. Elements of procedure An implementation may decide to implement a dual-thresholds mechanism to govern the origination of updated OSPF LSA or ISIS LSP. Similarly to other MPLS Traffic Engineering link characteristics, LSA/LSP origination trigger mechanisms are outside of the scope of this document. 5. IANA Considerations IANA will assign a new code point for the newly defined IS-IS sub-TLV (NB-0-BW-LSP) carried within the TLV 22 (suggested value =19) IANA will assign a new code point for the newly defined OSPF sub-TLV (NB-0-BW-LSP) carried within the Link TLV (Type 2) of the Traffic Engineering LSA (suggested value=19). 6. Security Considerations This document raises no new security issues for IS-IS and OSPF. 7. Acknowledgements The authors would like to thank Jean-Louis Le Roux for his useful inputs. 8. References 8.1. Normative References [I-D.ietf-isis-te-bis] Li, T. and H. Smit, "IS-IS extensions for Traffic Engineering", draft-ietf-isis-te-bis-00 (work in progress), September 2005. [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. [RFC3630] Katz, D., Kompella, K., and D. Yeung, "Traffic Engineering (TE) Extensions to OSPF Version 2", RFC 3630, September 2003. Vasseur, et al. Expires December 22, 2006 [Page 5] Internet-Draft draft-ietf-mpls-number-0-bw-te-lsps-02 June 2006 8.2. Informative References [RFC4090] Pan, P., Swallow, G., and A. Atlas, "Fast Reroute Extensions to RSVP-TE for LSP Tunnels", RFC 4090, May 2005. Vasseur, et al. Expires December 22, 2006 [Page 6] Internet-Draft draft-ietf-mpls-number-0-bw-te-lsps-02 June 2006 Authors' Addresses JP Vasseur (editor) Cisco Systems, Inc 1414 Massachusetts Avenue Boxborough, MA 01719 USA Email: jpv@cisco.com Matthew R. Meyer Global Crossing 3133 Indian Valley Tr. Howell, MI 48855 USA Email: mrm@gblx.net Kenji Kumaki KDDI Corporation Garden Air Tower Iidabashi, Chiyoda-ku, Tokyo, 102-8460 JAPAN Email: ke-kumaki@kddi.com Alberto Tempia Bonda Telecom Italia via G. Reiss Romoli 274 Torino, 10148 ITALIA Email: alberto.tempiabonda@telecomitalia.it Vasseur, et al. Expires December 22, 2006 [Page 7] Internet-Draft draft-ietf-mpls-number-0-bw-te-lsps-02 June 2006 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. 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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 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. Copyright Statement Copyright (C) The Internet Society (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. Acknowledgment Funding for the RFC Editor function is currently provided by the Internet Society. Vasseur, et al. Expires December 22, 2006 [Page 8]