Network Working Group L. Berger Request for Comments: 4873 LabN Consulting Updates: 3473, 4872 I. Bryskin Category: Standards Track ADVA Optical D. Papadimitriou Alcatel A. Farrel Old Dog Consulting May 2007 GMPLS Segment Recovery Status of This Memo This document specifies an Internet standards track protocol for the Internet community, and requests discussion and suggestions for improvements. Please refer to the current edition of the "Internet Official Protocol Standards" (STD 1) for the standardization state and status of this protocol. Distribution of this memo is unlimited. Copyright Notice Copyright (C) The IETF Trust (2007).
AbstractThis document describes protocol specific procedures for GMPLS (Generalized Multi-Protocol Label Switching) RSVP-TE (Resource ReserVation Protocol - Traffic Engineering) signaling extensions to support label switched path (LSP) segment protection and restoration. These extensions are intended to complement and be consistent with the RSVP-TE Extensions for End-to-End GMPLS Recovery (RFC 4872). Implications and interactions with fast reroute are also addressed. This document also updates the handling of NOTIFY_REQUEST objects.
1. Introduction ....................................................3 1.1. Conventions Used in This Document ..........................3 2. Segment Recovery ................................................4 2.1. Segment Protection .........................................6 2.2. Segment Re-routing and Restoration .........................6 3. ASSOCIATION Object ..............................................6 3.1. Format .....................................................7 3.2. Procedures .................................................7 3.2.1. Recovery Type Processing ............................7 3.2.2. Resource Sharing Association Type Processing ........7 4. Explicit Control of LSP Segment Recovery ........................8 4.1. Secondary Explicit Route Object Format .....................8 4.1.1. Protection Subobject ................................8 4.2. Explicit Control Procedures ................................9 4.2.1. Branch Failure Handling ............................10 4.2.2. Resv Message Processing ............................11 4.2.3. Admin Status Change ................................12 4.2.4. Recovery LSP Teardown ..............................12 4.3. Teardown From Non-Ingress Nodes ...........................12 4.3.1. Modified NOTIFY_REQUEST Object Processing ..........13 4.3.2. Modified Notify and Error Message Processing .......14 5. Secondary Record Route Objects .................................14 5.1. Format ....................................................14 5.2. Path Processing ...........................................15 5.3. Resv Processing ...........................................15 6. Dynamic Control of LSP Segment Recovery ........................16 6.1. Modified PROTECTION Object Format .........................16 6.2. Dynamic Control Procedures ................................17 7. Updated RSVP Message Formats ...................................18 8. Security Considerations ........................................20 9. IANA Considerations ............................................21 9.1. New Association Type Assignment ...........................21 9.2. Definition of PROTECTION Object Reserved Bits .............21 9.3. Secondary Explicit Route Object ...........................21 9.4. Secondary Record Route Object .............................21 9.5. New Error Code ............................................22 9.6. Use of PROTECTION Object C-type ...........................22 10. References ....................................................23 10.1. Normative References .....................................23 10.2. Informative References ...................................23
RFC4427] covers multiple types of protection, including end-to-end and segment-based approaches. "RSVP-TE Extensions in Support of End-to-End Generalized Multi-Protocol Label Switching (GMPLS) Recovery" [RFC4872] defines a set of extensions to support multiple types of recovery. The supported types include 1+1 unidirectional/ 1+1 bidirectional protection, LSP protection with extra-traffic (including 1:N protection with extra-traffic), pre-planned LSP re- routing without extra-traffic (including shared mesh), and full LSP re-routing. In all cases, the recovery is provided on an end-to-end basis, i.e., the ingress and egress nodes of both the protected and the protecting LSP are the same. [RFC4090] provides a form of segment recovery for packet MPLS-TE networks. Two methods of fast reroute are defined in [RFC4090]. The one-to-one backup method creates detour LSPs for each protected LSP at each potential point of local repair. The facility backup method creates a bypass tunnel to protect a potential failure point that is shared by multiple LSPs and uses label stacking. Neither approach supports the full set of recovery types supported by [RFC4872]. Additionally, the facility backup method is not applicable to most non-PSC (packet switch capable) switching technologies. The extensions defined in this document allow for support of the full set of recovery types supported by [RFC4872], but on a segment, or portion of the LSP, basis. The extensions allow (a) the signaling of desired LSP segment protection type, (b) upstream nodes to optionally identify where segment protection starts and stops, (c) the optional identification of hops used on protection segments, and (d) the reporting of paths used to protect an LSP. The extensions also widen the topological scope over which protection can be supported. They allow recovery segments that protect against an arbitrary number of nodes and links. They enable overlapping protection and nested protection. These extensions are intended to be compatible with fast reroute, and in some cases used with fast reroute. RFC2119]. In addition, the reader is assumed to be familiar with the terminology used in [RFC3209], [RFC3471], and [RFC3473], as well as [RFC4427], [RFC4426], [RFC4872], and [RFC4090].
RFC4090]. As with [RFC4090], the term "merge node" is used to refer to a node that terminates a recovery LSP, e.g., node E in the figure shown above. Segment protection or restoration is signaled using a working LSP and one or more segment recovery LSPs. Each segment recovery LSP is signaled as an independent LSP. Specifically, the Sender_Template object uses the IP address of the node originating the recovery path, e.g., node C in the topology shown above, and the Session object contains the IP address of the node terminating the recovery path, e.g., node E shown above. There is no specific requirement on LSP ID value, Tunnel ID, and Extended Tunnel ID. Values for these fields are selected normally, including consideration for the make-before- break concept (as described in [RFC3209]). Intermediate nodes follow standard signaling procedures when processing segment recovery LSPs. A segment recovery LSP may be protected itself using segment or end- to-end protection/restoration. Note, in PSC environments, it may be desirable to construct the Sender_Template and Session objects per [RFC4090].
When [RFC4090] isn't being used, the association between segment recovery LSPs with other LSPs is indicated using the ASSOCIATION object defined in [RFC4872]. The ASSOCIATION object is used to associate recovery LSPs with the LSP they are protecting. Working and protecting LSPs, as well as primary and secondary LSPs, are identified using LSP Status as described in [RFC4872]. The O-bit in the segment flags portion of the PROTECTION object is used to identify when a recovery LSP is carrying the normal (active) traffic. An upstream node can permit downstream nodes to dynamically identify branch and merge points by setting the desired LSP segment protection bits in the PROTECTION object. These bits are defined below. Optionally, an upstream node, usually the ingress node, can identify the endpoints of a segment recovery LSP. This is accomplished using a new object. This object uses the same format as an Explicit Route Object (ERO) and is referred to as a Secondary Explicit Route object (SERO); see Section 4.1. SEROs also support a new subobject to indicate the type of protection or restoration to be provided. At a minimum, an SERO will indicate a recovery LSP's initiator, protection/restoration type and terminator. Standard ERO semantics (see [RFC3209]) can optionally be used within and SERO to explicitly control the recovery LSP. A Secondary Record Route object (SRRO) is defined for recording the path of a segment recovery LSP; see Section 5. SEROs are carried between the node creating the SERO, typically the ingress, and the node initiating a recovery LSP. The node initiating a recovery LSP uses the SERO to create the ERO for the recovery LSP. At this (branch) node, all local objects are removed, and the new protection subobject is used to create the PROTECTION object for the recovery LSP. It is also possible to control the handling of a failure to establish a recovery LSP. SRROs are carried in Path messages between the node terminating a recovery LSP, the merge node, and the egress. SRROs are used in Resv messages between a branch node and the ingress. The merge node of a recovery LSP creates an SRRO by copying the RRO from the Path message of the associated recovery LSP into a new SRRO object. Any SRROs present in the recovery LSP's Path message are also copied. The branch node of a recovery LSP creates an SRRO by copying the RRO from the Resv message of associated recovery LSP into a new SRRO object. Any SRROs present in the recovery LSP's Resv message are also copied. Notify request processing is also impacted by LSP segment recovery. Per [RFC3473], only one NOTIFY_REQUEST object is meaningful and should be propagated. Additional NOTIFY_REQUEST objects are used to identify recovery LSP branch nodes.
RFC4872]: 1+1 Unidirectional Protection (Section 5), 1+1 Bidirectional Protection (Section 6), and 1:1 Protection With Extra-Traffic (Section 7). The segment protection forms of these protection approaches all operate much like their end-to-end counterparts. Each behaves just like its end-to-end counterpart, with the exception that the protection LSP protects only a portion of the working LSP. The type of protection to be used on a segment protection LSP is indicated, to the protection LSP's ingress, using the protection SERO subobject defined in Section 4.1. The switch-over processing for segment 1+1 Bidirectional protection and 1:1 Protection With Extra-Traffic follows the same procedures as end-to-end protection forms; see Sections 6.2 and 7.2 of [RFC4872] for details. RFC4872]: Re-routing without Extra-Traffic (Section 8), Shared-Mesh Restoration (Section 9), (Full) LSP Re-routing (Section 11). As with protection, these approaches are supported on a segment basis. The segment forms of re-routing and restoration operate exactly like their end-to-end counterparts, with the exception that the restoration LSP recovers only a portion of the working LSP. The type of re-routing or restoration to be used on a segment restoration LSP is indicated, to the restoration LSP's ingress, using the new protection SERO subobject. RFC4090] isn't being used. The ASSOCIATION object is defined in [RFC4872]. In this document, we define a new Association Type field value to support make-before-break; the formats and procedures defined in [RFC4872] are not otherwise modified.
RFC4872] for the definition of other fields and values. RFC4090]. RFC4872], but processing and identification occur with respect to segment recovery LSPs. Note that this means that multiple ASSOCIATION objects of type recovery may be present on an LSP. RFC3209]. The defined support only works with LSPs that share the same LSP egress. With the introduction of segment recovery LSPs, it is now possible for an LSP endpoint to change during make-before- break. A node includes an ASSOCIATION object with a Resource Sharing Association Type in an outgoing Path message when it wishes to indicate resource sharing across an associated set of LSPs. The Association Source is set to the originating node's router address. The Association ID MUST be set to a value that uniquely identifies the association of LSPs. This MAY be set to the working LSP's LSP ID. Once included, an ASSOCIATION object with a Resource Sharing Association Type SHOULD NOT be removed from the Path messages associated with an LSP.
Any node processing a Path message for which the node does not have a matching state, and which contains an ASSOCIATION object with a Resource Sharing type, examines existing LSPs for matching Association Type, Association Source, and Association ID values. If any match is found, then [RFC3209] style resource sharing SHOULD be provided between the new and old LSPs. See [RFC3209] for additional details. Section 4.2. The protection subobject is not valid for use with the Explicit and Record Route objects and MUST NOT be included in those objects. The format of the protection subobject is defined as follows: 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |L| Type | Length | Reserved | C-Type | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | PROTECTION Object Contents | | ... | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ L-bit This is defined in [RFC3209] and MUST be set to zero for protection subobjects.
Type 37 Protection Length As defined in [RFC3209], Section 4.3.3. Reserved This field is reserved. It MUST be set to zero on transmission and MUST be ignored on receipt. C-Type The C-Type of the included PROTECTION object. PROTECTION Object Contents The contents of the PROTECTION object, with the format matching the indicated C-Type, excluding the object header.
determination is made by examining the first object of each SERO and seeing if the address indicated in the subobject can be associated with the local node. If any of indicated addresses are associated with the local node, then the local node is a branch node. If the local node is not a branch node, all received SEROs MUST be transmitted, without modification, in the corresponding outgoing Path message. At a branch node, the SERO, together with the Path message of LSP being recovered, provides the information to create the recovery LSP. The Path message for the recovery LSP is created at the branch node by cloning the objects carried in the incoming Path message of the LSP being protected. Certain objects are replaced or modified in the recovery LSP's outgoing Path message. The Sender_template object MUST be updated to use an address (in its Tunnel Sender Address field) on the local node, and the LSP ID MUST be updated to ensure uniqueness. The Session object MUST be updated to use the address indicated in the final subobject of the SERO as the tunnel endpoint address, the tunnel ID MAY be updated, and the extended tunnel ID MUST be set to the local node address. The PROTECTION object is replaced with the contents of the matching SERO protection subobject, when present. In all cases, the R-bit of a new PROTECTION object is reset (0). Any RROs and EROs present in the incoming Path message MUST NOT be included in the recovery LSP. A new ERO MUST be included, with the contents of the SERO that indicated a local branch. As with all EROs, no local information (local address and any protection subobjects) is carried in the ERO carried in the recovery LSP's outgoing Path message. The SERO that indicated a local branch MUST be omitted from the recovery LSP's outgoing Path message. Note, by default, all other received SEROs are passed in the recovery LSP's outgoing Path message. SEROs MAY be omitted, from the recovery LSP's outgoing Path message as well as the outgoing Path message for the LSP being protected, when the SERO does not relate to the outgoing path message. The resulting Path message is used to create the recovery LSP. From this point on, Standard Path message processing is used in processing the resulting Path message.
rules. This includes generation of a standard PathErr message. When LSP state is removed due to a local failure or a PathErr message with the Path_State_Removed flag set (1), the node MUST send a PathTear message downstream on all other branches. When a failure or received PathErr message is associated with a recovery LSP, processing is based on the R-bit in addition to the Path_State_Removed flag. In all cases, a received PathErr message is first processed per standard processing rules and the failure or received PathErr message SHOULD trigger the generation of a PathErr message upstream for the LSP being protected. The outgoing PathErr message SHOULD indicate an error of "Routing Problem/LSP Segment Protection Failed". The outgoing PathErr message MUST include any SEROs carried in a received PathErr message. If no SERO is present in a received PathErr message or when the failure is local, then an SERO that matches the errored LSP or failed branch MUST be added to the outgoing PathErr message. When a PathErr message with the Path_State_Removed flag cleared (0) is received, the outgoing (upstream) PathErr message SHOULD be sent with the Path_State_Removed flag cleared (0). When a PathErr message for a recovery LSP with the Path_State_Removed flag set (1) is received, the processing node MUST examine the R-bit (as defined below) of the LSP being protected. The R-bit is carried in the PROTECTION object that triggered the initiation of the recovery LSP. When the R-bit is not set (0), the outgoing (upstream) PathErr message SHOULD be sent with the Path_State_Removed flag cleared (0). When the R-bit is set (1), the outgoing (upstream) PathErr message MUST be sent with the Path_State_Removed flag set (1). In all cases where an outgoing (upstream) PathErr message is sent with the Path_State_Removed flag set (1), all path state for the LSP being protected MUST be removed, and the node MUST send a PathTear message downstream on all active branches.
RFC3473], including generation of Resv messages. When the most recently received upstream ADMIN_STATUS object has the R bit set, branch nodes wait for a Resv message with a matching ADMIN_STATUS object to be received on all branches before relaying a corresponding Resv message upstream. RFC3209] and [RFC3473]. This includes with and without setting the administrative status. RFC3209] and [RFC2205]), and MUST also relay a PathTear on every recovery LSP. All PathTear messages (received from upstream and locally originated) may be concurrently sent downstream. RFC3473], the ingress node originates a Path message with the D and R bits set in the ADMIN_STATUS object. The admin status change procedure defined in Section 4.2.3 MUST then be followed. Once the ingress receives all expected Resv messages, it MUST follow the teardown procedure described in Section 126.96.36.199.
the LSP ingress, which can then signal the removal of the recovery LSP. It is also possible for the node initiating the teardown to remove a Recovery LSP in a non-graceful manner. In this case, the initiator sends a PathTear message downstream and a PathErr message with a "Confirmation" indication (error code and value set to zero), and the Path_State_Removed flag set (1) toward the LSP ingress node. This manner of non-ingress node teardown is NOT RECOMMENDED because in some cases it can result in the removal of the LSP being protected.
source address of the recovery LSP and, in the case of a branch node, matches the tunnel endpoint address of the recovery LSP. The matching NOTIFY_REQUEST object will normally be the first of the listed NOTIFY_REQUEST objects. Note, to cover certain backwards compatibility scenarios, the NOTIFY_REQUEST object SHOULD NOT be removed if it is the sole NOTIFY_REQUEST object. Note this requires the following change to [RFC3473], Section 4.2.1: o old text: If a message contains multiple NOTIFY_REQUEST objects, only the first object is meaningful. Subsequent NOTIFY_REQUEST objects MAY be ignored and SHOULD NOT be propagated. o new text: If a message contains multiple NOTIFY_REQUEST objects, only the first object used is in notification. Subsequent NOTIFY_REQUEST objects MUST be propagated in the order received.
RFC4872]. LSP Segment Recovery Flags are used to indicate when LSP segment recovery is desired. When these bits are set, branch and merge nodes are dynamically identified. Note, the procedures defined in this section parallel the explicit control procedures defined above in Section 4.2. The primary difference is in the creation of a recovery LSP's ERO. RFC4872]. The format of the flags are: 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Length | Class-Num(37) | C-Type (2) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |S|P|N|O| Reserved | LSP Flags | Reserved | Link Flags| +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |I|R| Reserved | Seg.Flags | Reserved | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ In-Place (I): 1 bit When set (1) indicates that the desired segment recovery type indicated in the LSP Segment Recovery Flag is already in place for the associated LSP. Required (R): 1 bit When set (1) indicates that failure to establish the indicated protection should result in a failure of the LSP being protected. Segment Recovery Flags (Seg.Flags): 6 bits This field is used to indicate when an upstream node desires LSP Segment recovery to be dynamically initiated where possible. The values used in this field are identical to the values defined for LSP Flags; see [RFC4872].
See [RFC4872] for the definition of other fields.
The resulting Path message is used to create the recovery LSP. While the recovery LSP exists, the PROTECTION object in the original Path message (unless overridden by local policy) MUST also be updated with the In-Place bit set (1). From this point on, Standard Path message processing is used in processing the resulting and original Path messages. The merge node of a dynamically controlled recovery LSP SHOULD reset (0) the In-Place bit in the PROTECTION object of the outgoing Path message associated with the terminated recovery LSP. Unlike with explicit control, if the creation of a dynamically identified recovery LSP fails for any reason, the recovery LSP is removed, and no error message or indication is sent upstream. With this exception, all the other procedures for explicitly controlled recovery LSPs apply to dynamically controlled recovery LSPs. These other procedures are defined above in Sections 4.2.1 through 4.2.4.
The format of the sender description for unidirectional LSPs is: <sender descriptor> ::= <SENDER_TEMPLATE> <SENDER_TSPEC> [ <ADSPEC> ] [ <RECORD_ROUTE> ] [ <SUGGESTED_LABEL> ] [ <RECOVERY_LABEL> ] [ <SECONDARY_RECORD_ROUTE> ... ] The format of the sender description for bidirectional LSPs is: <sender descriptor> ::= <SENDER_TEMPLATE> <SENDER_TSPEC> [ <ADSPEC> ] [ <RECORD_ROUTE> ] [ <SUGGESTED_LABEL> ] [ <RECOVERY_LABEL> ] <UPSTREAM_LABEL> [ <SECONDARY_RECORD_ROUTE> ... ] The format of a PathErr message is as follows: <PathErr Message> ::= <Common Header> [ <INTEGRITY> ] [ [<MESSAGE_ID_ACK> | <MESSAGE_ID_NACK>] ... ] [ <MESSAGE_ID> ] <SESSION> <ERROR_SPEC> [ <ACCEPTABLE_LABEL_SET> ... ] [ <SECONDARY_EXPLICIT_ROUTE> ... ] [ <POLICY_DATA> ... ] <sender descriptor> The format of a Resv message is as follows: <Resv Message> ::= <Common Header> [ <INTEGRITY> ] [ [<MESSAGE_ID_ACK> | <MESSAGE_ID_NACK>] ... ] [ <MESSAGE_ID> ] <SESSION> <RSVP_HOP> <TIME_VALUES> [ <RESV_CONFIRM> ] [ <SCOPE> ] [ <NOTIFY_REQUEST> ... ] [ <ADMIN_STATUS> ] [ <POLICY_DATA> ... ] <STYLE> <flow descriptor list> <flow descriptor list> ::= <FF flow descriptor list> | <SE flow descriptor>
<FF flow descriptor list> ::= <FLOWSPEC> <FILTER_SPEC> <LABEL> [ <RECORD_ROUTE> ] [ <SECONDARY_RECORD_ROUTE> ... ] | <FF flow descriptor list> <FF flow descriptor> <FF flow descriptor> ::= [ <FLOWSPEC> ] <FILTER_SPEC> <LABEL> [ <RECORD_ROUTE> ] [ <SECONDARY_RECORD_ROUTE> ... ] <SE flow descriptor> ::= <FLOWSPEC> <SE filter spec list> <SE filter spec list> ::= <SE filter spec> | <SE filter spec list> <SE filter spec> <SE filter spec> ::= <FILTER_SPEC> <LABEL> [ <RECORD_ROUTE> ] [ <SECONDARY_RECORD_ROUTE> ... ] RFC3473]. It does not introduce any new signaling messages, nor change the relationship between LSRs that are adjacent in the control plane. The procedures defined in this document result in an increase in the amount of topology information carried in signaling messages since the presence of SEROs and SRROs necessarily means that there is more information about LSP paths carried than in simple EROs and RROs. Thus, in the event of the interception of a signaling message, slightly more could be deduced about the state of the network than was previously the case, but this is judged to be a very minor security risk as this information is already available via routing. Otherwise, this document introduces no additional security considerations. See [RFC3473] for relevant security considerations.
RFC4872]) located at http://www.iana.org/assignments/gmpls-sig-parameters. Value Type ----- ---- 2 Resource Sharing (R) [RFC4873] RFC4872]. As no IANA registry for these bits is requested in [RFC4872], no IANA action is required related to this definition. http://www.iana.org/assignments/rsvp-parameters. A new class named SECONDARY_EXPLICIT_ROUTE has been created in the 11bbbbbb range (200) with the following definition: Class Types or C-types: Same values as EXPLICIT_ROUTE object (C-Num 20) For Class 1, C-Type 1, the following additional Subobject type is defined: 37 PROTECTION [RFC4873] http://www.iana.org/assignments/rsvp-parameters.
A new class named SECONDARY_RECORD_ROUTE has been created in the 11bbbbbb range (201) with the following definition: Class Types or C-types: Same values as RECORD_ROUTE object (C-Num 21) For Class 1, C-Type 1, the following additional Subobject type is defined: 37 PROTECTION [RFC4873] http://www.iana.org/assignments/rsvp-parameters. 21 = LSP Segment Protection Failed [RFC4873] Section 14.1. of [RFC4872]).
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. [RFC2205] Braden, R., Zhang, L., Berson, S., Herzog, S., and S. Jamin, "Resource ReSerVation Protocol (RSVP) -- Version 1 Functional Specification", RFC 2205, September 1997. [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. [RFC3471] Berger, L., Ed., "Generalized Multi-Protocol Label Switching (GMPLS) Signaling Functional Description", RFC 3471, January 2003. [RFC3473] Berger, L., Ed., "Generalized Multi-Protocol Label Switching (GMPLS) Signaling - Resource ReserVation Protocol-Traffic Engineering (RSVP-TE) Extensions", RFC 3473, January 2003. [RFC4872] Lang, J.P., Ed., Rekhter, Y., Ed., and D. Papadimitriou, Ed., "RSVP-TE Extensions in support of End-to-End Generalized Multi-Protocol Label Switching (GMPLS) Recovery", RFC 4872, May 2007. [RFC4090] Pan, P., Swallow, G., and A. Atlas, "Fast Reroute Extensions to RSVP-TE for LSP Tunnels", RFC 4090, May 2005. [RFC4426] Lang, J., Ed., Rajagopalan, B., Ed., and D. Papadimitriou, Ed., "Generalized Multi-Protocol Label Switching (GMPLS) Recovery Functional Specification," RFC 4426, March 2006. [RFC4427] Mannie, E., Ed., and D. Papadimitriou, Ed., "Recovery (Protection and Restoration) Terminology for Generalized Multi-Protocol Label Switching (GMPLS)", RFC 4427, March 2006.
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