CCAMPNetworking Working Group Jean-Philippe Vasseur IETF Internet Draft (Editor)JP. Vasseur, Ed. Internet-Draft Cisco Systems, Inc Proposed status:Status: Informational Cisco Systems YuichiY. Ikejiri Expires: August 12, 2006 NTT Communications Corporation RaymondR. Zhang BT Infonet Service Corporation Expires: November 2005 May 2005February 8, 2006 Reoptimization of Multiprotocol Label Switching (MPLS) Traffic Engineering (TE) loosely routed Label Switch Path (LSP) draft-ietf-ccamp-loose-path-reopt-01.txtdraft-ietf-ccamp-loose-path-reopt-02.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. 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 August 12, 2006. Copyright Notice Copyright (C) The Internet Society (2005). All Rights Reserved.(2006). Abstract This document defines a mechanism for the reoptimization of loosely routed MPLS and GMPLS (Generalized Multiprotocol Label Switching) Traffic Engineering LSPs. A loosely routed LSP is defined as one that does not contain a full explicit route identifying each LSR along the path of the LSP at the time it is signaled by the ingress LSR. Such an LSP is(TE) LSPs signaled with no ERO, with an ERO that contains at least one loose hop, or with an ERO that contains an abstract node that is not a simple abstract node (that is, an abstract node that identifies more than one LSR).RSVP-TE. This document proposes a mechanism that allows a TE LSP head-end LSR to trigger a new path re- evaluationre-evaluation on every hop having a next hop defined as a loose or abstract hop and a mid-point LSR to signal to the head-end LSR that a better path exists (compared to the current path in use) or that the TE LSP must be reoptimized because of some maintenance required on the TE LSP path. The proposed mechanism applies to the cases of intra and inter-domain (IGP area or Autonomous System) packet and non-packet TE LSPs following a loosely routed path. Conventions used in this documentRequirements 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.RFC 2119 [RFC2119]. Table of contentsContents 1. Notice.........................................................3Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3 2. Introduction...................................................3Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 3. Establishment of a loosely routed TE LSP.......................4LSP . . . . . . . . . . . 4 4. Reoptimization of a loosely routed TE LSP path.................5path . . . . . . . . 6 5. Signalling extensions..........................................6 5.1extensions . . . . . . . . . . . . . . . . . . . . 6 5.1. Path re-evaluation request.................................6 5.2request . . . . . . . . . . . . . . . . 7 5.2. New error value sub-codes..................................6sub-codes . . . . . . . . . . . . . . . . 7 6. Mode of operation..............................................7 6.1operation . . . . . . . . . . . . . . . . . . . . . . 7 6.1. Head-end reoptimization control............................7 6.2control . . . . . . . . . . . . . 7 6.2. Reoptimization triggers....................................7 6.3triggers . . . . . . . . . . . . . . . . . 8 6.3. Head-end request versus mid-point explicit notification modes..........................................................7 5.3.1functions . . . . . . . . . . . . . . . . . . 8 6.3.1. Head-end request mode.......................................7 5.3.2function . . . . . . . . . . . . . . 8 6.3.2. Mid-point explicit notification mode........................9 5.3.3. . . . . . . . . . . 9 6.3.3. ERO caching.................................................9caching . . . . . . . . . . . . . . . . . . . . . 10 7. Interoperability..............................................10Applicability and Interoperability . . . . . . . . . . . . . . 10 8. Security considerations.......................................10 9.IANA considerations...........................................10Considerations . . . . . . . . . . . . . . . . . . . . . 11 9. Security Considerations . . . . . . . . . . . . . . . . . . . 11 10. Acknowledgments..............................................10Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 12 11. Intellectual property considerations.........................11 12. References...................................................11 11.1References . . . . . . . . . . . . . . . . . . . . . . . . . . 12 11.1. Normative references........................................11 11.2References . . . . . . . . . . . . . . . . . . . 12 11.2. Informative references......................................11 13.References . . . . . . . . . . . . . . . . . . 12 Authors' Addresses...........................................12 14. FullAddresses . . . . . . . . . . . . . . . . . . . . . . . . 13 Intellectual Property and Copyright Statement.....................................12Statements . . . . . . . . . . 14 1. Notice The procedures describedTerminology Terminology used in this document are entirely optional within an MPLS or GMPLS network. Implementations that do not supportABR: Area Border Router. ERO: Explicit Route Object. LSR: Label Switch Router. TE LSP: Traffic Engineering Label Switched Path. TE LSP head-end: head/source of the procedures described in this document will interoperate seamlessly with those that do. Further, an implementation that does not supportTE LSP. TE LSP tail-end: tail/destination of the procedures described in this document will not be impactedTE LSP. IGP Area: OSPF Area or implicated by a neighboring implementation thatIS-IS level. Intra-area TE LSP: TE LSP whose path does implement the procedures. An ingress implementation that choosesnot to support the procedures described in this document may still achieve re-optimization by periodically issuing a speculative make-before-break replacement of an LSP without trying to discovery whether a more optimaltransit across areas. Inter-area TE LSP: A TE LSP whose path transits across at least two different IGP areas. Inter-AS MPLS TE LSP: A TE LSP whose path transits across at least two different ASs or sub-ASs (BGP confederations). 2. Introduction This document defines a mechanism for the reoptimization of loosely routed MPLS and GMPLS (Generalized Multiprotocol Label Switching) Traffic Engineering LSPs signaled with RSVP-TE (see [RFC3209] and [RFC3473]). A loosely routed LSP is available indefined as one that does not contain a downstream domain.full explicit route identifying each LSR along the path of the LSP at the time it is signaled by the ingress LSR. Such a procedure would not be in conflictan LSP is signaled with any mechanismsno ERO, with an ERO that contains at least one loose hop, or with an ERO that contains an abstract node that is not already documented in [RFC3209] and [RFC3473]. 2. Introductiona simple abstract node (that is, an abstract node that identifies more than one LSR). The Traffic Engineering WorkWorking Group (TE WG) has specified a set of requirements for inter-area [INTER-AREA-TE-REQ]and inter-AS [INTER- AS-TE-REQ]MPLS Traffic Engineering.Engineering (see [RFC4105] and [RFC4216]). Both requirements documents specify the need for some mechanism providing an option for the head- endhead-end to control the reoptimization process,process should a more optimal path exist in a downstream domain (IGP area or Autonomous System). This document defines a solution to meet this requirement and proposes a set of mechanisms that allow: -two mechanisms: (1) The TE LSPfirst mechanism allows a head-end LSR to trigger a new path re-evaluation on every hop having a next hop defined as a loose hop or abstract node, - Anode and get a notification from the mid-point on whether a better path exists. (2) The second mechanism allows a mid-point LSR to explicitly signal to the head-end LSR that either a better path exists to reach a loose/abstract hop (compared to the current path in use) or that the TE LSP must be reoptimized because of some maintenance required onalong the TE LSP path. In this case, the notification is sent by the mid- point LSR without being polled by the head-end LSR. A better path is defined as a lower cost path, where the cost is determined by the metric used to compute the path. 3. Establishment of a loosely routed TE LSP The aim of this section is purely to remind the mechanisms involved in the establishment of a loosely routed TE LSP (in line with [RFC3209]) and does not introduce any new protocol extensions or mechanisms. In the context of this document, a loosely routed LSP is defined as one that does not contain a full explicit route identifying each LSR along the path of the LSP at the time it is signaled by the ingress LSR. Such an LSP is signaled with no ERO, with an ERO that contains at least one loose hop, or with an ERO that contains an abstract node that is not a simple abstract node (that is, an abstract node that identifies more than one LSR). As definedspecified in [RFC3209], loose hops are listed in the Explicit Route Object (ERO)ERO object of the RSVP Path message with the L flag of the IPv4 or the IPv6 prefix sub-object set. Each LSR along the path whose next hop is specified as a loose hop or a non-specific abstract node triggers a path computation (also referred to as an ERO expansion), before forwarding the RSVP Path message downstream. The computed path may either be partial (up to the next loose hop) or complete (set of strict hops up to the TE LSP destination). Note that the examples in the rest of this document are provided in the context of MPLS inter-area TE but the proposed mechanism equally applies to loosely routed paths within a single routing domain and across multiple Autonomous Systems. The examples below are provided with OSPF as the IGP but the described set of mechanisms similarly apply to IS-IS. An example of an explicit loosely routed TE LSP signaling. <---area 1--><-area 0--><-area 2-> R1---R2----R3---R6 R8---R10 | | | / | \ | | | | / | \ | | | | / | \| R4---------R5---R7----R9---R11 Assumptions - R3, R5, R8 and R9 are ABRs - The path of an inter-area TE LSP T1 from R1 (head-end LSR) to R11 (tail-end LSR) is defined on R1 as the following loosely routed path: R1-R3(loose)-R8(loose)-R11(loose). R3, R8 and R11 are defined as loose hops. Step 1: R1 determines that the next hop (R3) is a loose hop (not directly connected to R1) and then performs an ERO expansion operation to reach the next loose hops R3. The new ERO becomes: R2(S)-R3(S)-R8(L)-R11(L) where: S: Strict hop (L=0) L: Loose hop (L=1) The R1-R2-R3 path obeyssatisfies T1's set of constraints. Step 2: the RSVP Path message is then forwarded by R1 following the EROpath specified in the ERO object and reaches R3 with the following content: R8(L)-R11(L)R8(L)-R11(L). Step 3: R3 determines that the next hop (R8) is a loose hop (not directly connected to R3) and then performs an ERO expansion operation to reach the next loose hops R8. The new ERO becomes: R6(S)-R7(S)-R8(S)-R11(L). Note: in this example, the assumption is made that the path is computed on a per loose hop basis, also referred to a partial route computation. Note that someother path computation techniques may result in complete paths (set of strict hops up to the final destination). Step 4: the same procedure applies atis repeated by R8 to reach T1's destination (R11). 4. Reoptimization of a loosely routed TE LSP path Once a loosely routed explicit TE LSP is set up, it is maintained through normal RSVP procedures. During TE LSP life time, a more optimal path might appear between an LSR and its next loose hop (for the sake of illustration, suppose in the example above that a link between R6 and R8 is added or restored that provides a preferable path between R3 and R8 (R3-R6-R8) than the existing R3-R6-R7-R8 path). Since a preferable (e.g. shorter) path might not be visible from the head-end LSR by means of the IGP if itthe head-end LSR does not belong to the head-end IGP area, the head-end cannot make use of this shorter path (and reroute the LSP using a make before break)make-before-break technique as described in [RFC3209]) when appropriate. Hence, some mechanisma new mechanisms specified in this document is required to detect the existence of such a preferable path and to notify the head-end LSR accordingly. This document defines a mechanism that allows: - A head-end LSR to trigger on every LSR whose next hop is a loose hop or an abstract node the re-evaluation of the current path in order to detect a potentialpotentially more optimal path, - A mid-point LSR whose next hop is a loose-hop or an abstract node to signal (using a new Error value sub-code carried in a RSVP PathErrPERR message) to the head-end LSR that a more preferable path exists (a path with a lower cost, where the cost definition is determined by some metric). Then onceOnce the existence of such a preferable path ishas been notified to the head-end LSR, the head-end LSR can decide (depending on the TE LSP characteristics) whether to perform a TE LSP graceful reoptimization such as the "Make Before Break" procedure defined in [RFC3209]."make-before-break" procedure. There is another scenario whereby notifying the head-end LSR of the existence of a better path is desirable: if the current path is about the fail due to some (link or node) required maintenance. This mechanism allows the head-end LSR to reoptimize a TE LSP making use of the non disruptive make before breakmake-before-break procedure if and only if a preferable path exists and if such a reoptimization is desired. 5. Signalling extensions A new flag in the SESSION ATTRIBUTE object and new Error value sub- codes in the ERROR SPEC object are proposed in this document (to be assigned by IANA). 5.15.1. Path re-evaluation request The following new flag of the SESSION_ATTRIBUTE object (C-Type 1 and 7) is defined (suggested value to be confirmed by IANA): Path re-evaluation request: 0x20 This flag indicates that a path re-evaluation (of the current path in use) is requested. Note that this does not trigger any LSP Reroute but instead just signals the request to evaluate whether a preferable path exists. Note: in case of link bundling for instance, although the resulting ERO might be identical, this might give the opportunity for a mid- point LSR to locally select another link within a bundle, although strictly speaking, the ERO has not changed. 5.25.2. New error value sub-codes As defined in [RFC3209], the ERROR-CODE 25 in ERROR SPECERROR-SPEC object corresponds to a Notify Error. This document adds three new error value sub-codes (suggested values to be confirmed by IANA): 6 Preferable path exists 7 Local link maintenance required 8 Local node maintenance required The details about the local maintenance required modes are detailed in section 18.104.22.168.2. 6. Mode of operation 6.16.1. Head-end reoptimization control The notification process of a preferable path (shorter path or new path due to some maintenance required on the current path) is by nature de-correlated from the reoptimization operation. In other words, the location where a potentially preferable path is discovered does not have to be where the TE LSP is actually reoptimized. This document applies to the context of a head-end reoptimization. 6.26.2. Reoptimization triggers There are threeseveral possible reoptimization triggers:triggers. For example, such reoptimization triggers are: - Timer-based: a reoptimization is triggered (process evaluating whether a more optimal path can be found) when a configurable timer expires, - Event-driven: a reoptimization is triggered when a particular network event occurs (such as a "Link-UP" event), - Operator-driven: a reoptimization is manually triggered by the Operator. It is RECOMMENDED for an implementation supporting the extensions proposed in this document to support the aforementioned modes as path re-evaluation triggers. 6.36.3. Head-end request versus mid-point explicit notification modesfunctions This document defines two modes:functions: 1) "Head-end requesting mode":function": the request for a new path evaluation of a loosely routed TE LSP is requested by the head- endhead-end LSR. 2) "Mid-point explicit notification":notification function": a mid-point LSR having determined that a preferable path (than the current path is use) exists or having the need to perform a link/node local maintenance explicitly notifies the head-end LSR whichthat will in turn decide whether to perform a reoptimization. 22.214.171.124.1. Head-end request mode In this mode, whenfunction When a timer-based reoptimization is triggered on the head-end LSR or the operator manually requests a reoptimization, the head-end LSR immediately sends an RSVP Path message with the "Path re-evaluation request" bit of the SESSION-ATTRIBUTE object set. This bit is then cleared in subsequent RSVP path messages sent downstream. In order to handle the case of a lost Path message, the solution consists of relying on the reliable messaging mechanism described in [REFRESH-REDUCTION].[RFC2961]. Upon receiving a Path message with the "Path re-evaluation request" bit set, every LSR for which the next abstract node contained in the ERO is defined as a loose hop/abstract node,node performs the following set of actions: A path re-evaluation is triggered and the newly computed path is compared to the existing path: - If a preferable path can be found, the LSR performing the path re-evaluationre- evaluation MUST immediately send an RSVP PathErrPErr to the head- endhead-end LSR (Error code 25 (Notify), Error sub-code=6 (better path exists)). At this point, the LSR MAY decide to not propagate such bit in subsequent RSVP Path messages sent downstream for the re-evaluated TE LSP: this mode is the RECOMMENDED mode for the reasons described below. The sending of an RSVP PathErrPERR Notify message "Preferable path exists" to the head-end LSR will notify the head-end LSR of the existence of a preferable path (e.g in a downstream area/AS or in another location within a single domain). Hence, triggering additional path re-evaluationsre- evaluations on downstream nodes is unnecessary. The only motivation to forward subsequent RSVP Path messages with the "Path re-evaluation request" bit of the SESSION-ATTRIBUTE object set would be to trigger path re- evaluationre-evaluation on downstream nodes that could in turn cache some potentially better paths downstream with the objective to reduce the signaling setup delay, should a reoptimization be performed by the head-end LSR. - If no preferable path can be found, the recommended mode is for an LSR to relay the request (by setting the "Path re- evaluation"re-evaluation" bit of the SESSION-ATTRIBUTE object in RSVP path message sent downstream). Note that, by preferable path, we mean a path having a lower cost. If the RSVP Path message with the "Path re-evaluation request" bit set is lost, then the next request will be sent when the next reoptimization trigger will occur on the head-end LSR. The solution to handle RSVP reliable messaging has been defined in [REFRESH- REDUCTION].[RFC2961]. The network administrator may decide to establish some local policy specifying to ignore such request or to consider those requests not more frequently than a certain rate. The proposed mechanism does not make any assumption of the path computation method performed by the ERO expansion process. 126.96.36.199.2. Mid-point explicit notification mode InBy contrast with the head-end request function, in this mode,case, a mid-pointmid- point LSR whose next hop is a loose hop or an abstract node can locally trigger a path re-evaluation when a configurable timer expires, some specific events occur (e.g. link-up event for example) or the user explicitly requests it. If a preferable path is found compared to the existing one,path in use, the LSR sends an RSVP PathErrPERR to the head-endhead- end LSR (Error code 25 (Notify), Error sub-code=6 ("preferable path exists"). There are other circumstances whereby any mid-point LSR MAY send an RSVP PathErrPERR message with the objective for the TE LSP to be rerouted by its head-end LSR: when a link or a node will go down for local maintenance reasons. In this case, the LSR where a local maintenance must be performed is responsible for sending an RSVP PathErrPERR message with Error code 25 and Error sub-code=7 or 8 depending on the affected network element (link or node). Then the first upstream node having performed the ERO expansion MUST perform the following set of actions: - The link (sub-code=7) or the node (sub-code=8) MUST be locally registered for further reference (the TE database must be updated) - The RSVP PathErrPERR message MUST be immediately forwarded upstream to the head-end LSR. Note that in the case of TE LSP spanning multiple administrative domains, it may be desirable for the boundary LSR to modify the RSVP PathErrPERR message and insert its own address for confidentiality reason. Upon receiving an RSVP PathErrPERR message with Error code 25 and Error sub-codesub- code 7 or 8, the Head-end LSR MUSTSHOULD perform a TE LSP reoptimization. Note that those modesthe two functions (head-end and mid-point driven) are not exclusive:exclusive from each other: both the timer and event- drivenevent-driven reoptimization triggers can be implemented on the head-end and/or any mid-point LSR with potentially different timer values for the timer driven reoptimization case. A head-end LSR MAY decide upon receiving an explicit mid-point notification to delay its next path re-evaluation request. 188.8.131.52.3. ERO caching Once a mid-point LSR has determined that a preferable path exists (after a reoptimization request has been received by the head-end LSR or the reoptimization timer on the mid-point has fired),expired), the more optimal path MAY be cached on the mid-point LSR for a limited amount of time to avoid having to recompute a path once the head-LSR performs a make before break.make-before-break. This mode is optional. A default value for the caching timer of 5 seconds is suggested. 7. Applicability and Interoperability The procedures described in this document are entirely optional within an MPLS or GMPLS network. Implementations that do not support the procedures described in this document will interoperate seamlessly with those that do. Further, an implementation that does not support the procedures described in this document will not be impacted or implicated by a neighboring implementation that does implement the procedures. An ingress implementation that chooses not to support the procedures described in this document may still achieve re-optimization by periodically issuing a speculative make-before-break replacement of an LSP without trying to discovery whether a more optimal path is available in a downstream domain. Such a procedure would not be in conflict with any mechanisms not already documented in [RFC3209] and [RFC3473]. An LSR not supporting the "Path re-evaluation request" bit of the SESSION-ATTRIBUTE object SHALL forward it unmodified. A head-end LSR not supporting an RSVP PathErrPERR with Error code 25 message and Error sub-code = 6, 7 or 8 MUST just silently ignore such RSVP PathErrPERR message. 8. Security considerations This document defines a mechanism forIANA Considerations IANA will assign a mid-point LSRnew flag named "Path re-evaluation request" in the SESSION-ATTRIBUTE object (C-Type 1 and 7) specified in [RFC3209]. Suggested value is (to be confirmed by IANA) 0x20. IANA will also assign three new error sub-code values for the RSVP PERR Notify message (Error code=25). Suggested values are (to be confirmed by IANA): 6 Preferable path exists 7 Local link maintenance required 8 Local node maintenance required 9. Security Considerations This document defines a mechanism for a mid-point LSR to notify the head-end LSR of this existence of a preferable path or the need to reroute the TE LSP for maintenance purposes. Hence, in case of a TE LSP spanning multiple administrative domains, it may be desirable for a boundary LSR to modify the RSVP PathErrPERR message (Code 25, Error sub-code=6,7sub- code=6,7 or 8) so as to preserve confidentiality across domains. Furthermore, a head-end LSR may decide to ignore explicit notification coming from a mid-point residing in another domain. Similarly, an LSR may decide to ignore (or accept but up to a pre- defined rate) path re-evaluation requests originated by a head-end LSR of another domain. 9. IANA considerations IANA will assign a new flag named "Path re-evaluation request" in the SESSION-ATTRIBUTE object (C-Type 1 and 7) specified in [RFC3209]. Suggested value is (to be confirmed by IANA) 0x20. IANA will also assign three new error sub-code values for the RSVP PERR Notify message (Error code=25). Suggested values are (to be confirmed by IANA): 6 Preferable path exists 7 Local link maintenance required 8 Local node maintenance required10. AcknowledgmentsAcknowledgements The authors would like to thank Carol Iturralde, Miya Kohno, Francois Le Faucheur, Philip Matthews, Jim Gibson, Jean-Louis Le Roux, Kenji Kumaki, Anca Zafir, Dimitri Papadimitriou for their useful comments. A special thank to Adrian Farrel for his very valuable inputs. 11. References 11.1. Normative References [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. [RFC2961] Berger, L., Gan, D., Swallow, G., Pan, P., Tommasi, F., and S. Molendini, "RSVP Refresh Overhead Reduction Extensions", RFC 2961, April 2001. [RFC3209] Awduche, D., Berger, L., Gan, D., Li, T., Srinivasan, V., and G. Swallow, "RSVP-TE: Extensions to RSVP for LSP Tunnels", RFC 3209, December 2001. [RFC3473] Berger, L., "Generalized Multi-Protocol Label Switching (GMPLS) Signaling Resource ReserVation Protocol-Traffic Engineering (RSVP-TE) Extensions", RFC 3473, January 2003. 11.2. Informative References [RFC4105] Le Roux, J., Vasseur, J., and J. Boyle, "Requirements for Inter-Area MPLS Traffic Engineering", RFC 4105, June 2005. [RFC4216] Zhang, R. and J. Vasseur, "MPLS Inter-Autonomous System (AS) Traffic Engineering (TE) Requirements", RFC 4216, November 2005. Authors' Addresses JP Vasseur (editor) Cisco Systems, Inc 1414 Massachusetts Avenue Boxborough, MA 01719 USA Email: firstname.lastname@example.org Yuichi Ikejiri NTT Communications Corporation 1-1-6, Uchisaiwai-cho, Chiyoda-ku Tokyo, 100-8019 Japan Email: : email@example.com Raymond Zhang BT Infonet 2160 E. Grand Ave. El Segundo, CA 90025 USA Email: firstname.lastname@example.org Intellectual property considerationsProperty 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 email@example.com. 12. References 12.1 Normative references [RFC] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels," RFC 2119. [RFC3209] Awduche et al, "RSVP-TE: Extensions to RSVP for LSP Tunnels", RFC3209, December 2001. [RFC3473] Berger L. et al.,"Generalized Multi-Protocol Label Switching (GMPLS) Signaling Resource ReserVation Protocol-Traffic Engineering (RSVP-TE) Extensions", RFC 3473, January 2003. [REFRESH-REDUCTION] Berger et al, "RSVP Refresh Overhead Reduction Extensions", RFC2961, April 2001. 12.2 Informative references [TE-REQ] Awduche et al, "Requirements for Traffic Engineering over MPLS", RFC2702, September 1999. [INTER-AREA-TE-REQ], Le Roux, Vasseur, Boyle et al. "Requirements for Inter-area MPLS Traffic Engineering", draft-ietf-tewg-interarea- mpls-te-req-03, November 2004. [INTER-AS-TE-REQ] Zhang et al, "MPLS Inter-AS Traffic Engineering requirements", draft-ietf-tewg-interas-mpls-te-req-09.txt, September 2004, Work in progress. [INTER-DOMAIN-FW] Farrel A., Vasseur JP. and Ayyangar A., "A Framework for Inter-Domain MPLS Traffic Engineering", draft-ietf- ccamp-inter-domain-framework-02.txt, May 2005. Work in progress. [INTER-DOMAIN-SIG] Ayyangar A. and Vasseur JP., "Inter domain GMPLS Traffic Engineering - RSVP-TE extensions", draft-ietf-ccamp-inter- domain-rsvp-te-00.txt", February 2005. Work in progress. [INTER-DOMAIN-PATH-COMP] Vasseur JP., Ayyangar A., "A Per-domain path computation method for computing Inter-domain Traffic Engineering (TE) Label Switched Path (LSP)", draft-ietf-ccamp-inter- domain-pd-path-comp-00.txt, February 2005. Work in progress. 13. Authors' Addresses Jean-Philippe Vasseur (Editor) CISCO Systems, Inc. 300 Beaver Brook Boxborough, MA 01719 USA Email: firstname.lastname@example.org Yuichi Ikejiri NTT Communications Corporation 1-1-6, Uchisaiwai-cho, Chiyoda-ku Tokyo 100-8019 JAPAN Email: email@example.com Raymond Zhang Infonet Services Corporation 2160 E. Grand Ave. El Segundo, CA 90025 USA Email: firstname.lastname@example.org 14. Full Copyright Statement Copyright (C) The Internet Society (2005). 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 AND THE INTERNET ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS OR IMPLIED,INCLUDINGIMPLIED, 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.