--- 1/draft-ietf-mpls-ldp-interarea-01.txt 2008-02-01 20:12:17.000000000 +0100 +++ 2/draft-ietf-mpls-ldp-interarea-02.txt 2008-02-01 20:12:17.000000000 +0100 @@ -1,18 +1,19 @@ Network Working Group B. Decraene Internet Draft J.L. Le Roux - Document: draft-ietf-mpls-ldp-interarea-01.txt France Telecom + Document: draft-ietf-mpls-ldp-interarea-02.txt France Telecom + Expiration Date: August 2008 I. Minei Juniper Networks, Inc. - November 2007 + February 2008 LDP extension for Inter-Area LSP 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. @@ -51,25 +52,25 @@ 4. Problem statement...........................................3 5. Label Mapping Procedure.....................................4 6. Application examples........................................5 6.1. Inter-area LSPs.............................................5 6.2. Use of static routes........................................7 7. Caveats for deployment......................................7 7.1. Deployment consideration....................................7 7.2. Impact on routing convergence time..........................8 8. Security Considerations.....................................8 9. IANA Considerations.........................................8 - 10. References..................................................8 - 10.1. Normative References........................................8 - 10.2. Informative References......................................8 + 10. References..................................................9 + 10.1. Normative References........................................9 + 10.2. Informative References......................................9 11. Acknowledgments.............................................9 - 12. Author's Addresses..........................................9 + 12. Author's Addresses.........................................10 1. 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. 2. Terminology IGP Area: OSPF Area or IS-IS level @@ -187,25 +188,30 @@ By "matching FEC Element", one should understand an IP longest match. That is, either the LDP FEC element exactly matches an entry in the IP RIB or the FEC element is a subset of an IP RIB entry. There is no match for other cases such as the FEC element is a superset of a RIB entry. Note that with this longest match Label Mapping Procedure, each LSP established by LDP still strictly follows the shortest path(s) defined by the IGP. - FECs selected by this "Longest Match" label mapping procedure will be - distributed in an ordered way. However this procedure is applicable - to both independent and ordered distribution control mode. + FECs selected by this "Longest Match" label mapping procedure are + distributed in an ordered way.. + In case of LER failure, the removal of reachability to the FEC occurs + using standard LDP procedures as defined in [LDP]. Similarly, the FEC + will be removed in an ordered way through the propagation of label + withdraw messages. The use of this reachability information by + application layers using the MPLS LSP (e.g., BGP) is outside the + scope of this document. - As per RFC 3036, LDP has already some interactions with the RIB. In + As per [LDP], LDP has already some interactions with the RIB. In particular, it needs to be aware of the following events: - prefix UP when a new IP prefix appears in the RIB - prefix DOWN when an existing prefix disappears - next-hop change when an existing prefix have new next hop following a routing change. With the longest match procedure, multiple FECs may be concerned by a single RIB prefix change. The LSR must check all the FECs which are a subset of this RIB prefix. So some LDP reactions following a RIB event are changed: @@ -308,55 +314,64 @@ The LDP specification defined in [LDP] would require on the ingress LER the configuration and the maintenance of one IP route per egress LER and per outgoing interface. The longest match Label Mapping Procedure described in this document only requires one IP route per outgoing interface. 7. Caveats for deployment -7.1. Deployment consideration +7.1. Deployment considerations LSRs compliant with this document are backward compatible with LSRs that comply with [LDP]. For the successful establishment of end-to-end MPLS LSPs whose FEC are aggregated in the RIB, this specification must be implemented on all LSRs in all areas where IP aggregation is used. If an LSR on the path does not support this procedure, then the LSP initiated on the egress LSR stops at this non compliant LSR. There are no other adverse effects. + A service provider currently leaking specific (/32) LER's loopback + addresses in the IGP and now considering performing IP aggregation on + ABR should be aware that this may result in suboptimal routing as + discussed in [RFC 2966]. + If all IP prefixes are leaked in the IGP backbone area and only stub areas use IP aggregation, LSRs in the backbone area don't need to be compliant with this document. 7.2. Impact on routing convergence time IGP convergence is based on two factors: the SPF calculation and FIB/LFIB update time. The SPF calculation scales O(N*Log(N)) where N is the number of Nodes. The FIB/LFIB update scales O(P) where P is the number of modified prefixes. Currently, with most routers implementations, the FIB/LFIB update is the dominant component [1]. The solution documented in this draft reduces the Linkstate database size and the number of FIB entries. However, it does not decrease the number of LFIB entries. In case of failure of the egress LER node, given that the IGP aggregates IP route on ABRs, the routing convergence behavior is - changed compared to [LDP]. As the IGP does not carries specifics + changed compared to [LDP]. As the IGP does not carry specifics prefixes outside of the egress area, the IGP will not propagate the - notification of node failure outside of the area and therefore - notification will rely on LDP. The FEC(s) of the egress LER will be - removed in an ordered way through the end-to-end propagation of the - LDP withdraw message. This failure notification may be faster or + notification of node failure outside of the area. So application + layers using the LSP may, as a local decision, use the availability + of the MPLS LSP -as advertised by LDP- to achieve LER egress fault + notification in addition to application layer fault detection + mechanisms. For some applications (e.g., BGP) this is expected to be + faster. LDP will withdraw the FEC(s) of the egress LER in an ordered + way through the end-to-end propagation of the LDP withdraw message. + Compared to the IGP, this LDP failure notification may be faster or slower depending on the implementations, the IGP timers used and the network topology (network diameter). In typical topologies, the convergence time is expected to be similar or even faster since there is no need to wait for three consecutive SPF/PRC timers. For all others failures (links, Ps and ABRs nodes), the failure notification and the convergence are unchanged. 8. Security Considerations @@ -384,54 +400,62 @@ Dual Environments", RFC 1195, December 1990 [VPLS-BGP] Kompella, K., Rekhter, Y., "Virtual Private LAN Service (VPLS) Using BGP for Auto-discovery and Signaling", RFC 4761, January 2007. [VPLS-LDP] Lasserre, M., Kompella, V., "Virtual Private LAN Service (VPLS) Using Label Distribution Protocol (LDP) Signaling", RFC 4762, January 2007. + [RFC 2966] Li, T., Przygienda, T., Smit, H., "Domain-wide Prefix + Distribution with Two-Level IS-IS", RFC 2966, October 2000. + [ID-RSVP-TE] Farrel, Ayyangar, Vasseur, " Inter domain MPLS and GMPLS Traffic Engineering - RSVP-TE extensions", draft-ietf- ccamp-inter-domain-rsvp-te, work in progress. [1] Francois, P., Filsfils, C., and Evans, J. 2005. "Achieving sub- second IGP convergence in large IP networks". ACM SIGCOMM 11. Acknowledgments Authors would like to thank Yakov Rekhter, Stefano Previdi, Vach - Kompella, Bob Thomas, Luca Martini, Clarence Filsfils, Benoit - Fondeviole, Gilles Bourdon and Christian Jacquenet for the useful - discussions on this subject, their review and comments. + Kompella, Bob Thomas, Clarence Filsfils, Kireeti Kompella, Luca + Martini, Sina Mirtorabi, Dave McDysan, Benoit Fondeviole, Gilles + Bourdon and Christian Jacquenet for the useful discussions on this + subject, their review and comments. -12. Author's Addresses +Authors' Addresses Bruno Decraene France Telecom - 38-40 rue du General Leclerc + 38 rue du General Leclerc 92794 Issy Moulineaux cedex 9 France - bruno.decraene@orange-ftgroup.com - Jean Louis Le Roux + EMail: bruno.decraene@orange-ftgroup.com + + Jean-Louis Le Roux France Telecom 2, avenue Pierre-Marzin 22307 Lannion Cedex France - jeanlouis.leroux@orange-ftgroup.com + + EMail: jeanlouis.leroux@orange-ftgroup.com + Ina Minei Juniper Networks 1194 N. Mathilda Ave. Sunnyvale, CA 94089 - ina@juniper.net + + EMail: ina@juniper.net Intellectual Property Considerations 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 @@ -445,21 +469,21 @@ 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. Copyright Statement - Copyright (C) The IETF Trust (2007). + 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. 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