Networking Working Group JP. Vasseur, Ed. Internet-Draft Cisco Systems, Inc Intended status: Standards Track Matthew. R. Meyer Expires:
February 19,March 5, 2009 Global Crossing K. Kumaki KDDI Corporation Alberto. Tempia Bonda Telecom Italia August 18,September 1, 2008 A Link-Type sub-TLV to convey the number of Traffic Engineering Label Switched Paths signalled with zero reserved bandwidth across a link draft-ietf-mpls-number-0-bw-te-lsps-11draft-ietf-mpls-number-0-bw-te-lsps-12 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 February 19,March 5, 2009. Abstract Several Link-type sub-TLVssub-Type-Lenght-Values (sub-TLVs) have been defined for OSPFOpen Shortest Path First (OSPF) and IS-ISIntermediate System to Intermediate System (IS-IS) in the context of Multiprotocol Label Switching (MPLS) Traffic Engineering (TE) in order to advertise some link characteristics such as the available bandwidth, traffic engineering metric, administrative group and so on. By making statistical assumptionassumptions about the aggregated traffic carried onto a set of TE Label Switched Paths (LSPs) signalled with zero bandwith (referred to as unconstrained TE LSP in this document), and with the knowledge of the number of unconstrained TE LSPs signalled across a link, algorithms can be designed to load balance (existing or newly configured) unconstrained TE LSP across a set of equal cost paths. This requires knowledge of the number of unconstrained TE LSPs 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. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . . 34 2. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 34 3. Protocol extensions . . . . . . . . . . . . . . . . . . . . . . 45 3.1. IS-IS . . . . . . . . . . . . . . . . . . . . . . . . . . . 45 3.2. OSPF . . . . . . . . . . . . . . . . . . . . . . . . . . . 56 4. Elements of procedure . . . . . . . . . . . . . . . . . . . . . 56 5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 56 6. Security Considerations . . . . . . . . . . . . . . . . . . . . 67 7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 67 8. References . . . . . . . . . . . . . . . . . . . . . . . . . . 67 8.1. Normative References . . . . . . . . . . . . . . . . . . . 67 8.2. Informative References . . . . . . . . . . . . . . . . . . 78 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 78 Intellectual Property and Copyright Statements . . . . . . . . . . 910 1. Terminology Terminology used in this document CSPF: Constrained Shortest Path First IGP : Interior Gateway Protocol LSA: Link State Advertisement LSP: Link State Packet MPLS: Multiprotocol Label Switching LSR: Label Switching Router SRLG: Shared Risk Link Group TE LSP: Traffic Engineering Label Switched Path Unconstrained TE LSP: A TE LSP signalled with a bandwidth equal to 0 2. Introduction 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 TE LSPs signalled with zero bandwidth (also referred to as unconstrained TE LSP in this document) between a set of LSRs (Label Switching Routers) and protecting these TE LSPs against link, SRLG (Shared Risk Link Group) and/or node failures with pre-established backup tunnels. The traffic routed onto such unconstrained TE LSPs simply follows the IGP shortest path (since the TE LSP computed by the path computation algorithm (e.g. CSPF) will be no different than the IGP (Interior Gateway Protocol) shortest path should the TE metric be equal to the IGP metric) but is protected with MPLS TE Fast Reroute. When a reoptimization process is triggered for an existing TE LSP, the decision on whether to reroute that TE LSP onto a different path is governed by the discovery of a lower cost path satisfying the constraints (other metricmetrics such that the percentage of reserved bandwidth or the number of hops can also be used). Unfortunately, metrics such as the path cost or the number of hops may be ineffective in various circumstances: for instanceexample, in the presencecase of a symmetrical network with ECMPs (Equal Cost Multi-Paths) in symmetrical networks whenMulti-Paths), if the network operator uses unconstrained TE LSPs are used, such metrics (e.g. path cost, number of hops, ...) are usually ineffective andLSP, this may lead to a poorly load balanced traffic.traffic: indeed, several paths between a source and a destination of a TE LSP may exist that have the same cost and the reservable amount of bandwidth along each path cannot be used as a tie-breaker. By making statistical assumptions about the aggregated traffic carried by a set of TE LSPs signalled with no bandwidth requirement (referred to as unconstrained TE LSPs in this document), algorithms can be designed to load balance (existing or newly configured) unconstrained TE Label Switched Paths (LSPs) across a set of equal cost paths. This requires knowledge of the number of unconstrained Traffic Engineering Label Switched Paths (TE LSPs) signalled across each link. Note that the specification of load balancing algorithms is outside the scope of this document and is referred to 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 (forpurposes, for example to evaluate the number of affected unconstrained TE LSPs in case of a link failure).failure. A set of Link-type sub-TLVs have been defined for OSPF and IS-IS (see [RFC3630] and [RFC3784])[I-D.ietf-isis-te-bis]) 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. As currently defined in [RFC3630] and [RFC3784][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 LSPs signalled across a link. Unconstrained TE LSPs that are configured and provisioned through a management system MAY be omitted from the count that is reported. 3. Protocol extensions Two Unconstrained TE LSP count sub-TLVs are defined that specify the number of TE LSPs signalled with zero bandwidth across a link. 3.1. IS-IS The IS-IS Unconstrained TE LSP Count Sub-TLV is OPTIONAL and MUST NOT appear more than once within the extended IS reachability TLV (type 22) specified in [RFC3784][I-D.ietf-isis-te-bis] or the MT Intermediate Systems TLV (type 222) specified in [RFC5120]. If a second instance of the Unconstrained TE LSP Count sub-TLV is present, the receiving system MUST only process the first instance of the sub-TLV. The IS-IS Unconstrained TE LSP Count Sub-TLV format is defined below: Type (1 octet): To be assigned by IANA (suggested value = 23) Length (1 octet): 2 Value (2 octets): number of unconstrained TE LSP(s) signalled across the link. 3.2. OSPF The OSPF Unconstrained TE LSP Count TLV is OPTIONAL and MUST NOT appear more than once within the Link TLV (Type 2) that is itself carried within the Traffic Engineering LSA specified in [RFC3630] or the OSPFv3 Intra-Area-TE LSA (function code 10) defined in [I-D.ietf-ospf-ospfv3-traffic]. If a second instance of the Unconstrained TE LSP Count sub-TLV is present, the receiving system MUST only process the first instance of the sub-TLV. The OSPF Unconstrained TE LSP Count Sub-TLV format is defined below: Type (2 octets): To be assigned by IANA (suggested value = 23) Length (2 octets): 4 Value (4 octets): number of unconstrained TE LSP(s) signalled across the link. 4. Elements of procedure The absence of the Unconstrained TE LSP Count (sub-)TLV shouldSHOULD be interpreted as an absence of information about the link. Similarly to other MPLS Traffic Engineering link characteristics, LSA/LSP origination trigger mechanisms are outside the scope of this document. Care must be given to not trigger the systematic flooding of a new IS-IS LSP or OSPF LSA with a too high granularity in case of change of the number of unconstrained TE LSPs. 5. IANA Considerations IANA has defined a sub-registry for the sub-TLVs carried in the IS-IS TLV 22. IANA is requested to assign a new TLV code-point for the Unconstrained TE LSP Count sub-TLV carried within the TLV 22. Suggested Value TLV Name Reference 23 Unconstrained TE LSP Count (sub-)TLV This document IANA has defined a sub-registry for the sub-TLVs carried in an OSPF TE Link TLV (type 2). IANA is requested to assign a new sub-TLV code-point for the Unconstrained TE LSP Count sub-TLV carried within the TE Link TLV. Suggested Value TLV Name Reference 23 Unconstrained TE LSP Count (sub-)TLV This document 6. Security Considerations The function described in this document does not create any new security issues for the OSPF and the IS-IS protocols. Security considerations are covered in [RFC2328] and [RFC2470][RFC5340] for the base OSPF protocol and in [RFC1195] and [I-D.ietf-isis-rfc3567bis] for IS-IS. A security framework for MPLS and Generalized MPLS can be found in [I-D.ietf-mpls-mpls-and-gmpls-security-framework]. 7. Acknowledgements The authors would like to thank Jean-Louis Le Roux, Adrian Farrel, Daniel King, Acee Lindem, Lou Berger, Attila TakacsTakacs, Pasi Eronen, Russ Housley, Tim Folk and Loa Anderson for their useful inputs. 8. References 8.1. Normative References [I-D.ietf-isis-rfc3567bis] Li, T. and R. Atkinson, "Intermediate System to Intermediate System (IS-IS) Cryptographic Authentication", draft-ietf-isis-rfc3567bis-03 (work in progress), July 2008. [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), April 2008. [I-D.ietf-ospf-ospfv3-traffic] Ishiguro, K., Manral, V., Davey, A., and A. Lindem, "Traffic Engineering Extensions to OSPF version 3", draft-ietf-ospf-ospfv3-traffic-13 (work in progress), June 2008. [RFC1195] Callon, R., "Use of OSI IS-IS for routing in TCP/IP and dual environments", RFC 1195, December 1990. [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", STD 54, RFC 2328, April 1998. [RFC2470] Crawford, M., Narten, T., and S. Thomas, "Transmission of IPv6 Packets over Token Ring Networks", RFC 2470, December 1998.[RFC3630] Katz, D., Kompella, K., and D. Yeung, "Traffic Engineering (TE) Extensions to OSPF Version 2", RFC 3630, September 2003. [RFC3784] Smit, H.[RFC5340] Coltun, R., Ferguson, D., Moy, J., and T. Li, "Intermediate System to Intermediate System (IS-IS) ExtensionsA. Lindem, "OSPF for Traffic Engineering (TE)",IPv6", RFC 3784, June 2004.5340, July 2008. 8.2. Informative References [I-D.ietf-mpls-mpls-and-gmpls-security-framework] Fang, L. and M. Behringer, "Security Framework for MPLS and GMPLS Networks", draft-ietf-mpls-mpls-and-gmpls-security-framework-03 (work in progress), July 2008. [RFC4090] Pan, P., Swallow, G., and A. Atlas, "Fast Reroute Extensions to RSVP-TE for LSP Tunnels", RFC 4090, May 2005. [RFC5120] Przygienda, T., Shen, N., and N. Sheth, "M-ISIS: Multi Topology (MT) Routing in Intermediate System to Intermediate Systems (IS-ISs)", RFC 5120, February 2008. Authors' Addresses JP Vasseur (editor) Cisco Systems, Inc 1414 Massachusetts Avenue Boxborough, MA 01719 USA Email: email@example.com Matthew R. Meyer Global Crossing 3133 Indian Valley Tr. Howell, MI 48855 USA Email: firstname.lastname@example.org Kenji Kumaki KDDI Corporation Garden Air Tower Iidabashi, Chiyoda-ku, Tokyo, 102-8460 JAPAN Email: email@example.com Alberto Tempia Bonda Telecom Italia via G. Reiss Romoli 274 Torino, 10148 ITALIA Email: firstname.lastname@example.org Full Copyright Statement Copyright (C) The IETF Trust (2008). 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. 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