CCAMP Working Group CCAMP GMPLS P&R Design Team Internet Draft Expiration Date: August 2004 J.P. Lang (Editor) Y. Rekhter (Editor) D. Papadimitriou (Editor) February 2004 RSVP-TE Extensions in support of End-to-End GMPLS-based Recovery draft-lang-ccamp-gmpls-recovery-e2e-signaling-03.txt Status of this Memo This document is an Internet-Draft and is in full conformance with all provisions of Section 10 of RFC2026. 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. For potential updates to the above required-text see: http://www.ietf.org/ietf/1id-guidelines.txt Abstract This document describes protocol specific procedures for GMPLS (Generalized Multi-Protocol Label Switching) RSVP-TE (Resource ReserVation Protocol - Traffic Engineering) signaling extensions to support end-to-end LSP recovery (protection and restoration). A generic functional description of GMPLS recovery can be found in a companion document. J.P.Lang et al. - Internet Draft û Expires August 2004 1 draft-lang-ccamp-gmpls-recovery-e2e-signaling-03.txt February 2004 1. Contributors This document is the result of the CCAMP Working Group Protection and Restoration design team joint effort. The following are the authors that contributed to the present memo: Deborah Brungard (AT&T) Rm. D1-3C22 - 200 S. Laurel Ave. Middletown, NJ 07748, USA E-mail: dbrungard@att.com Sudheer Dharanikota (Consult) E-mail: sudheer@ieee.org Jonathan Lang (Rincon Networks) E-mail: jplang@ieee.org Guangzhi Li (AT&T) 180 Park Avenue, Florham Park, NJ 07932, USA E-mail: gli@research.att.com Eric Mannie (Consult) Email: eric_mannie@hotmail.com Dimitri Papadimitriou (Alcatel) Fr. Wellesplein, 1 B-2018, Antwerpen, Belgium Email: dimitri.papadimitriou@alcatel.be Bala Rajagopalan (Tellium) 2 Crescent Place - P.O. Box 901 Oceanport, NJ 07757-0901, USA E-mail: braja@tellium.com Yakov Rekhter (Juniper) 1194 N. Mathilda Avenue Sunnyvale, CA 94089, USA E-mail: yakov@juniper.net 2. 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 [RFC2119]. In addition, the reader is assumed to be familiar with the terminology used in [GMPLS-ARCH], [RFC-3471], [RFC-3473] and referenced as well as [TERM] and [FUNCT]. J.P.Lang et al. - Internet Draft û Expires August 2004 2 draft-lang-ccamp-gmpls-recovery-e2e-signaling-03.txt February 2004 3. Introduction Generalized Multi-Protocol Label Switching (GMPLS) extends MPLS to include support for Layer-2 (L2SC), Time-Division Multiplex (TDM), Lambda Switch Capable (LSC), and Fiber Switch Capable (FSC) interfaces. GMPLS-based recovery uses control plane mechanisms (i.e., signaling, routing, link management mechanisms) to support data plane fault recovery. Note that the analogous (data plane) fault detection mechanisms are required to be present in support of the control plane mechanisms. In this document, the term "recovery" is generically used to denote both protection and restoration; the specific terms "protection" and "restoration" are only used when differentiation is required. The subtle distinction between protection and restoration is made based on the resource allocation done during the recovery phase (see [TERM]). A functional description of GMPLS-based recovery is provided in [FUNCT] and should be considered as a companion document to this memo which describes the protocol specific procedures for GMPLS RSVP-TE (Resource ReSerVation Protocol - Traffic Engineering) signaling (see [RFC-3473]) to support end-to-end recovery of an entire LSP from the head-end to the tail-end. The present memo addresses four types of end-to-end LSP recovery: 1+1 unidirectional/ 1+1 bi-directional 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. The simplest notion of end-to-end LSP protection is 1+1 unidirectional protection. Using this type of protection, a protecting LSP is signaled over a dedicated resource-disjoint alternate path to protect an associated working LSP. Normal traffic is simultaneously sent on both LSPs and a selector is used at the egress node to receive traffic from one of the LSPs. If a failure occurs along one of the LSPs, the egress node selects the traffic from the valid LSP. No coordination is required between the end nodes when a failure/switchover occurs. In 1+1 bi-directional protection, a protecting LSP is signaled over a dedicated resource-disjoint alternate path to protect the working LSP. Normal traffic is simultaneously sent on both LSPs (in both directions) and a selector is used at both ingress/egress nodes to receive traffic from the same LSP. This requires co-ordination between the end-nodes when switching to the protecting LSP. In 1:N (N =< 1) protection with extra-traffic, the protecting LSP is a fully provisioned and resource-disjoint LSP from the N working LSPs, that allows for carrying extra-traffic. The N working LSPs MAY be mutually resource-disjoint. Coordination between end-nodes is required when switching from one of the working to the protecting LSP. Note that M:N protection is out of scope of this document (though mechanisms it defines may be extended to cover it). J.P.Lang et al. - Internet Draft û Expires August 2004 3 draft-lang-ccamp-gmpls-recovery-e2e-signaling-03.txt February 2004 Pre-planned LSP re-routing (or restoration) relies on the establishment between the same pair of end-nodes of a working LSP and a protecting LSP that is link/node/SRLG disjoint from the working one. Here, the recovery resources for the protecting LSP are pre-reserved and explicit action is required to activate (i.e. commit resource allocation at the data plane) a specific protecting LSP instantiated during the (pre-)provisioning phase. Since the protecting LSP is not "active" (i.e. fully instantiated), it can not carry any extra-traffic (note that this does not mean that the corresponding resources can not used by other LSPs). Therefore, this mechanism protects against working LSP(s) failure(s) but requires activation of the protecting LSP after working LSP failure occurrence. This requires restoration signaling along the protecting path. "Shared-mesh" restoration can be seen as a particular case of pre-planned LSP re-routing that reduces the recovery resource requirements by allowing multiple protecting LSPs to share common link and node resources. The recovery resources are pre-reserved and explicit action is required to activate (i.e. commit resource allocation at the data plane) a specific protecting LSP instantiated during the (pre-)provisioning phase. This procedure requires restoration signaling along the protecting path. Note that in both cases, any lower priority LSP that would use the pre-reserved resources for the protecting LSP(s) MUST be preempted during the activation of the protecting LSP. Full LSP re-routing (or restoration) switches normal traffic to an alternate LSP that is fully established only after working LSP failure occurs. The new alternate route is selected at the LSP head- end node, it may reuse resources of the failed LSP at intermediate nodes and may include additional intermediate nodes and/or links. Note that crankback signaling (see [CRANK]) and LSP segment recovery are further detailed in dedicated companion documents. Also, there is no impact to Fast Reroute [FRR] introduced by end-to-end GMPLS-based recovery i.e. it is possible to use either method defined in FRR with end-to-end GMPLS-based recovery. The objects used and/or newly introduced by end-to-end recovery will be ignored by [FRR] conformant implementations, and FRR can operate on a per LSP basis as defined in [FRR]. 4. Overview 4.1 LSP Identification This section reviews terms previously defined in [RFC2205], [RFC3209], and [RFC3473]. LSP tunnels are identified by a combination of the SESSION and SENDER_TEMPLATE objects (see also [RFC-3209]). The relevant fields are as follows: IPv4 (or IPv6) tunnel end point address J.P.Lang et al. - Internet Draft û Expires August 2004 4 draft-lang-ccamp-gmpls-recovery-e2e-signaling-03.txt February 2004 IPv4 (or IPv6) address of the egress node for the tunnel. Tunnel ID A 16-bit identifier used in the SESSION that remains constant over the life of the tunnel. Extended Tunnel ID A 32-bit (or 16-byte) identifier used in the SESSION that remains constant over the life of the tunnel. Normally set to all zeros. Ingress nodes that wish to narrow the scope of a SESSION to the ingress-egress pair MAY place their IPv4 (or IPv6) address here as a globally unique identifier. IPv4 (or IPv6) tunnel sender address IPv4 (or IPv6) address for a sender node. LSP ID A 16-bit identifier used in the SENDER_TEMPLATE and FILTER_SPEC that can be changed to allow a sender to share resources with itself. The first three fields are carried in the SESSION object (Path and Resv message) and constitute the basic identification of the LSP tunnel. The last two fields are carried in the SENDER_TEMPLATE (Path message) and FILTER_SPEC objects (Resv message). The LSP ID is used to differentiate LSP tunnels that belong to the same session. 4.2 Recovery Attributes The recovery attributes includes all the parameters that determine the status of a LSP within the recovery scheme to which it is associated. These attributes are part of the PROTECTION object introduced in Section 14. 4.2.1 LSP Status The following bits are used in determining resource allocation and status of the LSP within the group of LSPs forming the protected entity: - S (Secondary) bit: enables distinction between primary and secondary LSPs. A primary LSP is a fully established LSP for which the resource allocation has been committed at the data plane (i.e. full cross-connection has been performed). Both working and protecting LSPs can be primary LSPs. A secondary LSP is an LSP that has been provisioned in the control plane only and for which J.P.Lang et al. - Internet Draft û Expires August 2004 5 draft-lang-ccamp-gmpls-recovery-e2e-signaling-03.txt February 2004 resource selection MAY have been done but for which the resource allocation has not been committed at the data plane (for instance, no cross-connection has been performed). Therefore, a secondary LSP is not immediately available to carry any traffic (requiring thus additional signaling to be available). A secondary LSP can only be a protecting LSP. The (data plane) resources allocated for a secondary LSP MAY be used by other LSPs until the primary LSP fails over to the secondary LSP. - P (Protecting) bit: enables distinction between working and protecting LSPs. A working LSP must be a primary LSP whilst a protecting LSP can be either a primary or a secondary LSP. When protecting LSP(s) are associated with working LSP(s), one also refers to the latter as protected LSPs. Note: The combination "secondary working" is not valid (only protecting LSPs can be secondary LSPs). Working LSPs are always primary LSPs (i.e. fully established) whilst primary LSPs can be either working or protecting LSPs. - O (Operational) bit: this bit is set when a protecting LSP is carrying the normal traffic after protection switching (i.e. applies only in case of dedicated LSP protection or LSP protection with extra-traffic, see Section 4.2.2). In this document, the PROTECTION object uses as a basis the PROTECTION object defined in [RFC-3471] and [RFC-3473] and defines additional fields within it. The fields defined in [RFC-3471] and [RFC-3473] are unchanged by this memo. 4.2.2 LSP Recovery The following classification is used to distinguish the LSP Protection Type with which LSPs can be associated at end-nodes (a distinct value is associated with each Protection Type in the PROTECTION object, see Section 14): - Full LSP Re-routing: set if a primary working LSP is dynamically recoverable using (non pre-planned) head-end re-routing. - Pre-planned LSP Re-routing without Extra-traffic: set if a protecting LSP is a secondary LSP that allows sharing of the pre-reserved recovery resources between one or more than one pair. When the secondary LSPs resources are not pre-reserved for a single pair, this type is referred to as "shared mesh" recovery. - LSP Protection with Extra-traffic: set if a protecting LSP is a dedicated primary LSP that allows for extra-traffic transport and thus precludes any sharing of the recovery resources between more than one pair. This type includes 1:N LSP protection with extra-traffic. J.P.Lang et al. - Internet Draft û Expires August 2004 6 draft-lang-ccamp-gmpls-recovery-e2e-signaling-03.txt February 2004 - Dedicated LSP Protection: set if a protecting LSP does not allow sharing of the recovery resources nor the transport of extra- traffic (implying in the present context, duplication of the signal over both working and protecting LSPs as in 1+1 dedicated protection). Note also that this document makes a distinction between 1+1 unidirectional and bi-directional dedicated LSP protection. For LSP protection, in particular when the data plane provides automated protection switching capability (see for instance ITU-T G.841 Recommendation), a Notification (N) bit is defined in the PROTECTION object. It allows for distinction between protection switching signaling via the control plane or via the data plane. Note: this document assumes that Protection Type values have end-to- end significance and that the same value is sent over the protected and the protecting path. In this context, shared-mesh for instance, appears from the end-nodes perspective as being simply an LSP re- routing without extra-traffic services. The net result of this is that a single bit (the S bit alone) does not allow determining whether resource allocation should be performed and this *with respect to* the status of the LSP within the protected entity. The introduction of the P bit solves this problem unambiguously. These bits MUST be processed on a hop-by-hop basis (independently of the LSP Protection Type context). This allows for an easier implementation of reversion signaling (see Section 12) but also facilitates the transparent delivery of protected services since any intermediate node is not required to know the semantic associated with the incoming LSP Protection Type value. 4.3 LSP Association The ASSOCIATION object, introduced in Section 16, is used to associate the working and protecting LSPs. When used for the working LSP signaling, the Association ID of the ASSOCIATION object (see Section 16) identifies the protecting LSP. When used for the protecting LSP signaling, this field identifies the LSP protected by the protecting LSP. 5. 1+1 Unidirectional Protection One of the simplest notions of end-to-end LSP protection is 1+1 unidirectional protection. Consider the following network topology: A---B---C---D \ / E---F---G J.P.Lang et al. - Internet Draft û Expires August 2004 7 draft-lang-ccamp-gmpls-recovery-e2e-signaling-03.txt February 2004 The paths [A,B,C,D] and [A,E,F,G,D] are node and link disjoint, ignoring the ingress/egress nodes A and D. A 1+1 protected path is established from A to D over [A,B,C,D] and [A,E,F,G,D] and traffic is transmitted simultaneously over both component paths (i.e. LSPs). When a failure occurs (say at node B) and is detected at end-node D, the receiver at D selects the normal traffic from the other LSP. From this perspective, 1+1 unidirectional protection can be seen as an uncoordinated protection switching mechanism acting independently at both end-points. Note also that both LSPs are fully instantiated (and thus activated) so that no resource sharing can be done along the protecting LSP (nor can any extra-traffic be transported). It is also RECOMMENDED to set the N bit since no protection switching signaling is assumed in this case. Also, for the protected LSP under failure condition, the Path_State_Removed Flag of the ERROR_SPEC object (see [RFC-3473]) SHOULD NOT be set upon PathErr message generation. Note: one should assume that both paths are SRLG disjoint otherwise, a failure would impact both working and protecting LSPs. 5.1. Identifiers Since both LSPs belong to the same session, the SESSION object MUST be the same for both LSPs. The LSP ID, however, MUST be different to distinguish between the two LSPs. A new PROTECTION object is included in the Path message. This object carries the desired end-to-end LSP Protection Type (in this case, "1+1 Unidirectional") as well as the LSP ID of the associated LSP referred to as the Association ID. This LSP Protection Type value is applicable to both uni- and bi-directional LSPs. It is also desirable to allow distinguishing the working LSP (from which the signal is taken) from the protecting LSP. This is achieved for the working LSP by setting in the PROTECTION object the S bit to 0, the P bit to 0, and the Association ID to the protecting LSP_ID. The protecting LSP is signaled by setting in this object the S bit to 0, the P bit to 1, and the Association ID to the associated protected LSP_ID. After protection switching completes (step 2), and after reception of the PathErr message, to keep track of the LSP from which the signal is taken, the protecting LSP SHOULD be signaled with the O- bit set. The formerly working LSP MAY be signaled with the A bit set in the ADMIN_STATUS object (see [RFC-3473]). This process assumes the tail-end node has notified the head-end node that traffic selection switchover has occurred. J.P.Lang et al. - Internet Draft û Expires August 2004 8 draft-lang-ccamp-gmpls-recovery-e2e-signaling-03.txt February 2004 6. 1+1 Bi-directional Protection 1+1 bi-directional protection is another scheme that provides end- to-end LSP protection. Consider the following network topology: A---B---C---D \ / E---F---G The LSPs [A,B,C,D] and [A,E,F,G,D] are node and link disjoint, ignoring the ingress/egress nodes A and D. A bi-directional LSP is established from A to D over each path and traffic is transmitted simultaneously over both LSPs. In this scheme, both end-points must receive traffic over the same LSP. When a failure is detected by one or both end-points of the LSP, both end-points must select traffic from the other LSP. This action must be coordinated between node A and D. From this perspective, 1+1 bi-directional protection can be seen as a coordinated protection switching mechanism between both end-points. Note also that both LSPs are fully instantiated (and thus activated) so that no resource sharing can be done along the protection path (nor can any extra-traffic be transported). Note: one should assume that both paths are SRLG disjoint otherwise a failure would impact both working and protecting LSPs. 6.1. Identifiers Since both LSPs belong to the same session, the SESSION object MUST be the same in both LSPs. The LSP ID, however, MUST be different to distinguish between the two LSPs. A new PROTECTION object (see Section 14) is included in the Path message. This object carries the desired end-to-end LSP Protection Type (in this case, "1+1 Bi-directional") as well as the LSP ID of the associated LSP referred to as Association ID. This LSP Protection Type value is only applicable to bi-directional LSPs. It is also desirable to allow distinguishing the working (LSP from which the signal is taken) from the protecting LSP. This is achieved for the working LSP by setting in the PROTECTION object the S bit to 0, the P bit to 0, and the Association ID to the protecting LSP_ID. The protecting LSP is signaled by setting in this object the S bit to 0, the P bit to 1 and the Association ID to the associated protected LSP_ID. 6.2. End-to-End Switchover Request/Response To co-ordinate the switchover between end-points, an end-to-end switchover request is needed since a failure affecting one the LSPs J.P.Lang et al. - Internet Draft û Expires August 2004 9 draft-lang-ccamp-gmpls-recovery-e2e-signaling-03.txt February 2004 results in both end-points switching to the other LSP (resulting in receiving traffic from the other LSP) in their respective directions. This is done using the Notify message with a new Error Code indicating "Working LSP Failure (Switchover Request)". The Notify Ack message MUST be sent to confirm the reception of the Notify message (see [RFC-3473], Section 4.3). The procedure is as follows: 1. If an end-node (A or D) detects the failure of the working LSP (or a degradation of signal quality over the working LSP) or receives a Notify message including its SESSION object within the (see [RFC-3473]), it MUST begin receiving on the protecting LSP and send a Notify message reliably to the other end-node (D or A, respectively). This message MAY indicate the identity of the failed working link and other relevant information using the IF_ID ERROR_SPEC (see [RFC-3473]). Note: in this case, the IF_ID ERROR_SPEC replaces the ERROR_SPEC in the Notify message, otherwise the corresponding (data plane) information SHOULD be received in the PathErr/ResvErr message. 2. Upon receipt of the switchover message, the end-node (D or A, respectively) MUST begin receiving from the protection LSP and send a (Notify) Ack message to the other end-node (A or D, respectively) using reliable message delivery (see [RFC-2961]). Since the intermediate nodes (B,C,E,F and G) are assumed to be GMPLS signaling capable, each node adjacent to the failure MAY generate a Notify message directed either to the LSP head-end (upstream direction) or the LSP tail-end (downstream direction) or even both. Therefore, it is expected that these LSP terminating nodes (that MAY also detect the failure of the LSP from the data plane) provide either the right correlation mechanism to avoid repetition of the above procedure or just discard subsequent Notify messages corresponding to the same Session. In addition, for the working LSP under failure, the Path_State_Remove Flag of the ERROR_SPEC object (see [RFC-3473]) SHOULD NOT be set upon PathErr message generation. After protection switching completes (step 2), and after reception of the PathErr message, to keep track of the LSP from which the signal is taken, the protecting LSP SHOULD be signaled with the O- bit set. The formerly working LSP MAY be signaled with the A bit set in the ADMIN_STATUS object (see [RFC-3473]). Note: when the N bit is set, the end-to-end switchover request/ response exchange described above only provides control plane coordination (no actions are triggered at the data plane level). J.P.Lang et al. - Internet Draft û Expires August 2004 10 draft-lang-ccamp-gmpls-recovery-e2e-signaling-03.txt February 2004 7. 1:1 Protection with Extra-Traffic The most common case of end-to-end 1:N protection is to establish, between the same end-points, an end-to-end working LSP (thus, N = 1) and a dedicated end-to-end protecting LSP that are mutually link/ node/SRLG disjoint. This protects against working LSP failure(s). The protecting LSP is used for fast switchover when the working LSP fails. GMPLS signaling allows for the pre-provisioning of protecting LSPs by indicating in the Path message (in the PROTECTION object, see Section 14) that the LSPs are of type protecting. Here, working and protecting LSPs are signaled as primary LSPs; both are fully instantiated during the provisioning phase. Although the resources for the protecting LSP are pre-allocated, preemptable traffic may be carried end-to-end using this LSP (i.e. the protecting LSP is capable of carrying extra-traffic) with the caveat that this traffic will be preempted if the working LSP fails. Also, if extra-traffic is carried over the protecting LSP, the corresponding end-nodes may need to be notified of the failure in order to complete the switchover. The setup of the working LSP SHOULD indicate that the LSP head-end and tail-end node wish to receive Notify messages using the NOTIFY REQUEST object. The node upstream to the failure (upstream in terms of the direction an RSVP Path message traverses) SHOULD send an RSVP Notify message to the LSP head-end node, and the node downstream to the failure SHOULD send an RSVP Notify message to the LSP tail-end node. Upon receipt of the Notify messages, both the end-nodes MUST switch the (normal) traffic from the working LSP to the pre- configured protecting LSP (see Section 7.2). Moreover some coordination is required if extra-traffic is carried over the end- to-end protecting LSP. Note that if the working and the protecting LSP are established between the same end-nodes no further notification is required to indicate that the working LSPs are no longer protected. Consider the following topology: A---B---C---D \ / E---F---G The working LSP [A,B,C,D] could be protected by the protecting LSP [A,E,F,G,D]. Both LSPs are fully instantiated (resources are allocated for both working and protecting LSPs) and no resource sharing can be done along the protection path since the primary protecting LSP can carry extra-traffic. Note: one should assume that both paths are SRLG disjoint otherwise a failure would impact both working and protecting LSPs. J.P.Lang et al. - Internet Draft û Expires August 2004 11 draft-lang-ccamp-gmpls-recovery-e2e-signaling-03.txt February 2004 7.1 Identifiers Since both LSPs belong to the same session, the SESSION object MUST be the same in both LSPs. The LSP ID, however, MUST be different to distinguish between the protected LSP carrying working traffic and the protecting LSP that can carry extra-traffic. A new PROTECTION object (see Section 14) is included in the Path message used to setup the two LSPs. This object carries the desired end-to-end LSP Protection Type (in this case, "1:N Protection with Extra-Traffic"). This LSP Protection Type value is applicable to both uni- and bi-directional LSPs. The working LSP is signaled by setting in this object the S bit to 0, the P bit to 0 and the Association ID to the protecting LSP_ID. The protecting LSP is signaled by setting in this object the S bit to 0, the P bit to 1, and the Association ID to the associated protected LSP_ID. 7.2 End-to-End Switchover Request/Response To co-ordinate the switchover between end-points, an end-to-end switchover request is needed such that the affected LSP(s) are moved to the protecting LSP. Protection switching from the working to the protecting LSP (implying preemption of extra-traffic carried over the protecting LSP) must be initiated by one of the end-nodes (A or D). This operation may be done using a Notify message exchange with a new Error Code indicating "(Working) LSP Failure (Switchover Request)". The Notify Ack message MUST be sent to confirm the reception of the Notify message. The procedure is as follows: 1. If an end-node (A or D) detects the failure of the working LSP (or a degradation of signal quality over the working LSP) or receives a Notify message including its SESSION object within the (see [RFC-3473]), it disconnects the extra-traffic from the protecting LSP and send a Notify message reliably to the other end-node (D or A, respectively). This message MAY indicate the identity of the failed working link and other relevant information using the IF_ID ERROR_SPEC (see [RFC- 3473]). Note: in this case, the IF_ID ERROR_SPEC replaces the ERROR_SPEC in the Notify message, otherwise the corresponding information SHOULD be received in the PathErr/ResvErr message 2. Upon receipt of the switchover (i.e. end-to-end Notify) message, the end-node (D or A, respectively) MUST disconnect J.P.Lang et al. - Internet Draft û Expires August 2004 12 draft-lang-ccamp-gmpls-recovery-e2e-signaling-03.txt February 2004 the extra-traffic from the protecting LSP and begin sending/receiving normal traffic out/from the protecting LSP and send a (Notify) Ack message to the other end-node (A or D, respectively) using reliable message delivery (see [RFC 2961]). Also, the Notify message generated by the end-node is distinguishable from the one generated by an intermediate node, there is no possibility of connecting the extra traffic to the working LSP due to the receipt of Notify message from an intermediate node. 3. Upon receipt of the switchover (Notify) Ack message, the end-node (A or D, respectively) MUST begin receiving normal traffic from the protecting LSP. Note 1: a 2-phase protection switching signaling is used in the present context, a 3-phase signaling (see [FUNCT]) that would imply a notification message and a switchover request/response messages, is not considered here. Also, when the protecting LSPs do not carry extra-traffic, a 1-Phase protection switching signaling as defined in Section 6.2 MAY be used instead of the 2-Phase described here above. Note 2: when the N bit is set, the above end-to-end switchover request/response exchange does only provide control plane coordination (no actions are triggered at the data plane level). After protection switching completes (step 3), and after reception of the PathErr message, to keep track of the LSP from which the normal traffic is taken, the protecting LSP SHOULD be signaled with the O-bit set. In addition, the formerly working LSP MAY be signaled with the A bit set in the ADMIN_STATUS object (see [RFC-3473]). 7.3 1:N (N > 1) Protection with Extra-Traffic 1:N (N > 1) protection with extra-traffic assumes that the fully provisioned protecting LSP is resource-disjoint LSP from the N working LSPs. This protecting LSP allows thus for carrying extra- traffic. In addition, the N working LSPs (considered as identical in terms of traffic parameters) MAY be mutually resource-disjoint. Coordination between end-nodes is required when switching from one of the working to the protecting LSP. Each working LSP is signaled with both S bit and P bit set to 0. The LSP Flag is set to 0x04 (during LSP setup). Each Association ID points to the protecting LSP ID. The protecting LSP (carrying extra- traffic) is signaled with S bit set to 0 and P bits set to 1. The LSP Flag is set to 0x04 (during LSP setup). The Association ID is not significant (multiple protected LSPs) and MUST be set by default to the LSP ID of the protected LSP corresponding to N = 1. Any signaling procedure applicable to 1:1 protection with extra- traffic equally applies to 1:N protection with extra-traffic. J.P.Lang et al. - Internet Draft û Expires August 2004 13 draft-lang-ccamp-gmpls-recovery-e2e-signaling-03.txt February 2004 8. Re-routing without Extra-Traffic End-to-end (pre-planned) re-routing without extra-traffic relies on the establishment between the same pair of end-nodes of a working LSP and a protecting LSP that is link/node/SRLG disjoint from the working one. However, in this case the protecting LSP is not fully instantiated, thus, it can not carry any extra-traffic (note that this does not mean that the corresponding resources can not used by other LSPs). Therefore, this mechanism protects against working LSP failure(s) but requires activation of the protecting LSP after failure occurrence. Signalling is performed by indicating in the Path message (in the PROTECTION object, see Section 14) that the LSPs are of type working and protecting, respectively. Protecting LSPs are used for fast switchover when working LSPs fail. In this case, working and protecting LSPs are signaled as primary LSP and secondary LSP, respectively. Thus, only the working LSP is fully instantiated during the provisioning phase and for the protecting LSPs, no resources are committed at the data plane level (they are pre- reserved at the control plane level only). The setup of the working LSP SHOULD indicate (using the NOTIFY REQUEST object as specified in Section 4 of [RFC-3473]) that the LSP head-end node (and possibly the tail-end node) wish to receive a Notify message upon LSP failure occurrence. Upon receipt of the Notify message, the head-end node MUST switch the (normal) traffic from the working LSP to the protecting LSP after its activation. Note that since the working and the protecting LSP are established between the same end-nodes no further notification is required to indicate that the working LSPs are no longer protected. To make bandwidth pre-reserved for a protecting but not activated LSP, available for extra traffic this bandwidth could be included in the advertised Unreserved Bandwidth at priority lower (means numerically higher) than the Setup Priority of the protecting LSP. In addition, the Max LSP Bandwidth field in the Interface Switching Capability Descriptor sub-TLV should reflect the fact that the bandwidth pre-reserved for the protecting LSP is available for extra traffic. LSPs for extra traffic then can be established using the bandwidth pre-reserved for the protecting LSP by setting (in the Path message) the Setup Priority field of the SESSION_ATTRIBUTE object to X (where X is the Setup Priority of the protecting LSP) and the Holding Priority field at least to X+1. Also, if the resources pre-reserved for the protecting LSP are used by lower priority LSPs, these LSPs MUST be preempted when the protecting LSP is activated. Consider the following topology: A---B---C---D \ / E---F---G J.P.Lang et al. - Internet Draft û Expires August 2004 14 draft-lang-ccamp-gmpls-recovery-e2e-signaling-03.txt February 2004 The working LSP [A,B,C,D] could be protected by the protecting LSP [A,E,F,G,D]. Only the protected LSP is fully instantiated (resources are only allocated for the working LSP) therefore, the protecting LSP can not carry any extra-traffic. When a failure is detected on the working LSP (say at B), the error is propagated and/or notified to the ingress node (A), which activates the secondary protecting LSP instantiated during the (pre-)provisioning phase. This requires: (1) the ability to identify a "secondary protecting LSP" (hereby called the "secondary LSP") used to recover another primary working LSP (hereby called the "protected LSP") (2) the ability to associate the secondary LSP with the protected LSP (3) the capability to activate a secondary LSP after failure occurrence. In the following subsections, these features are described in more detail. 8.1 Identifiers Since both LSPs (i.e. the primary working and the secondary protecting LSPs) belong to the same session, the SESSION object MUST be the same in both LSPs. The LSP ID, however, MUST be different to distinguish between the protected LSP carrying working traffic and the secondary protecting LSP that can not carry extra-traffic. A new PROTECTION object (see Section 14) is used to setup the two LSPs. This object carries the desired end-to-end LSP Protection Type in this case, "Re-routing without Extra-Traffic") as well as the LSP ID of the association LSP. This LSP Protection Type value is applicable to both uni- and bi-directional LSPs. 8.2 Signaling Primary LSPs The new PROTECTION object is included in the Path message during signaling of the primary working LSP, with the end-to-end LSP Protection Type value set to "Re-routing without Extra-Traffic". Primary working LSPs are signaled by setting in this object the S bit to 0, the P bit to 0 and the Association ID to the protecting LSP_ID. 8.3 Signaling Secondary LSPs The new PROTECTION object carried in the Path message includes the desired end-to-end LSP Protection Type (in this case, "Re-routing without Extra-Traffic") as well as the LSP ID of the associated primary working LSP, which MUST be known before signaling of the secondary LSP. This LSP Protection Type value is applicable to both uni- and bi-directional LSPs. J.P.Lang et al. - Internet Draft û Expires August 2004 15 draft-lang-ccamp-gmpls-recovery-e2e-signaling-03.txt February 2004 Secondary (protecting) LSPs are signaled by setting in this object the S bit and the P bit to 1. With this setting, the resources for the protecting LSP SHOULD be pre-reserved, but not committed at the data plane level meaning that the internals of the switch need not be established until explicit action is taken to activate this secondary LSP. Activation of a secondary LSP is done using a modified Path message with the S bit set to 0 in the PROTECTION object. At this point, the link and node resources must be allocated for this LSP that becomes a primary LSP (ready to carry normal traffic). Two cases have to be covered here (see also [GMPLS-ARCH]) since secondary protecting LSPs are setup with resource pre-reservation but with or without label pre-selection (both allowing sharing of the recovery resources). In the former case (defined as the default), secondary LSP signaling does not necessitate any specific procedure compared to the one defined in [RFC-3473]. However, in the latter case, label (and thus resource) re-allocation MAY occur during the secondary LSP activation. This means that during the activation phase, labels MAY be re-assigned (with higher precedence over existing label assignment, see also [RFC-3471]). Note: in certain circumstances, it MAY be desirable to perform the activation of the secondary LSP in the upstream direction (Resv trigger message) instead of using the default downstream method. In this case, and in order to avoid any mis-ordering and any mis- interpretation between a refresh Resv and a trigger Resv message at intermediate nodes along the secondary LSP, upon reception of the Path message, the egress node MAY include the PROTECTION object in the Resv message. The latter is then processed on a hop by hop basis to activate the secondary LSP until reaching the ingress node. The PROTECTION object included in the Path message MUST be set as specified in this Section. The upstream activation behavior SHOULD be configurable on a local basis. 9. Shared-Mesh Restoration An approach to reduce recovery resource requirements is to have protection LSPs sharing network resources when the working LSPs that they protect are physically (i.e., link, node, SRLG, etc.) disjoint. This mechanism is referred to as shared mesh restoration and is described in [FUNCT]. Shared-mesh restoration can be seen as a particular case of pre-planned LSP re-routing (see Section 8) that reduces the recovery resource requirements by allowing multiple protecting LSPs to share common link and node resources. Here also, the recovery resources for the protecting LSPs are pre-reserved during the provisioning phase, thus an explicit signaling action is required to activate (i.e. commit resource allocation at the data plane) a specific protecting LSP instantiated during the (pre- )provisioning phase. This requires restoration signaling along the protecting LSP. J.P.Lang et al. - Internet Draft û Expires August 2004 16 draft-lang-ccamp-gmpls-recovery-e2e-signaling-03.txt February 2004 To make bandwidth pre-reserved for a protecting but not activated LSP, available for extra traffic this bandwidth could be included in the advertised Unreserved Bandwidth at priority lower (means numerically higher) than the Setup Priority of the protecting LSP. In addition, the Max LSP Bandwidth field in the Interface Switching Capability Descriptor sub-TLV should reflect the fact that the bandwidth pre-reserved for the protecting LSP is available for extra traffic. LSPs for extra traffic then can be established using the bandwidth pre-reserved for the protecting LSP by setting (in the Path message) the Setup Priority field of the SESSION_ATTRIBUTE object to X (where X is the Setup Priority of the protecting LSP) and the Holding Priority field at least to X+1. Also, if the resources pre-reserved for the protecting LSP are used by lower priority LSPs, these LSPs MUST be preempted when the protecting LSP is activated. Further, if the recovery resources are shared between multiple protecting LSPs, the corresponding working LSPs head-end nodes must be informed that they are no longer protected when the protecting LSP is activated to recover the normal traffic for the working LSP under failure. Consider the following topology: A---B---C---D \ / E---F---G / \ H---I---J---K The working LSPs [A,B,C,D] and [H,I,J,K] could be protected by [A,E,F,G,D] and [H,E,F,G,K], respectively. In order to achieve resource merging during the signaling of these protecting LSPs (i.e. resource sharing), the LSPs must have the same Session Ids, but the Session Id includes the target (egress) IP address. These addresses are not the same in this example. Resource sharing along E, F, G can only be achieved if the nodes E, F and G recognize that the LSP Type setting of the secondary LSPs is for protection (see PROTECTION object, Section 14) and acts accordingly. In this case, the protecting LSPs are not merged (which is useful since the paths diverge at G), but the resources can be shared. When a failure is detected on one of the working LSPs (say at B), the error is propagated and/or notified to the ingress node (A), which activates the protecting LSP (see Section 8). At this point, it is important that a failure on the other LSP (say at J) does not cause the other ingress (H) to send the data down the protecting LSP since the resources are already in use. This can be achieved by node E using the following procedure. When the capacity is first reserved for the protecting LSP, E should verify that the LSPs being protected ([A,B,C,D] and [H,I,J,K], respectively) do not share any common resources. Then, when a failure occurs (say at B) and the protecting LSP [A,E,F,G,D] is activated, E should notify H that the J.P.Lang et al. - Internet Draft û Expires August 2004 17 draft-lang-ccamp-gmpls-recovery-e2e-signaling-03.txt February 2004 resources for the protecting LSP [H,E,F,G,K] are no longer available. The following sub-sections details how shared mesh restoration can be implemented in an interoperable fashion using GMPLS RSVP-TE extensions (see [RFC-3473]). This includes: (1) the ability to identify a "secondary protecting LSP" (hereby called the "secondary LSP") used to recover another primary working LSP (hereby called the "protected LSP") (2) the ability to associate the secondary LSP with the protected LSP (3) the capability to include information about the resources used by the protected LSP while instantiating the secondary LSP. (4) the capability to instantiate during the provisioning phase several secondary LSPs in an efficient manner. (5) the capability to activate a secondary LSP after failure occurrence. In the following subsections, these features are described in detail. 9.1. Identifiers Since both LSPs (i.e. the primary working and the secondary protecting LSPs) belong to the same session, the SESSION object MUST be the same in both LSPs. The LSP ID, however, MUST be different to distinguish between the protected LSP carrying working traffic and the secondary protecting LSP that can not carry extra-traffic. A new PROTECTION object (see Section 14) is used to setup the two LSPs. This object carries the desired end-to-end LSP Protection Type in this case, "Re-routing without Extra-Traffic") as well as the LSP ID of the associated LSP. This LSP Protection Type value is applicable to both uni- and bi-directional LSPs. 9.2 Signaling Primary LSPs The new PROTECTION object is included in the Path message during signaling of the primary working LSP, with the end-to-end LSP Protection Type value set to "Re-routing without Extra-Traffic". Primary working LSPs are signaled by setting in this object the S bit to 0, the P bit to 0 and the Association ID to the protecting LSP_ID. 9.3 Signaling Secondary LSPs The new PROTECTION object carried in the Path message includes the desired end-to-end LSP Protection Type (in this case, "Re-routing without Extra-Traffic") as well as the LSP ID of the associated primary working LSP, which MUST be known before signaling of the J.P.Lang et al. - Internet Draft û Expires August 2004 18 draft-lang-ccamp-gmpls-recovery-e2e-signaling-03.txt February 2004 secondary LSP. This LSP Protection Type value is applicable to both uni- and bi-directional LSPs. Secondary (protecting) LSPs are signaled by setting in this object the S bit and the P bit to 1. Moreover, the Path message used to instantiate this LSP MUST include at least one PRIMARY PATH ROUTE object (see Section 15) that further allows for recovery resource sharing at each intermediate node along the secondary path. With this setting, the resources for the protecting LSP SHOULD be pre- reserved, but not committed at the data plane level meaning that the internals of the switch need not be established until explicit action is taken to activate this LSP. Activation of a secondary LSP is done using a modified Path message with the S bit set to 0 in the PROTECTION object. At this point, the link and node resources must be allocated for this LSP that becomes a primary LSP (ready to carry normal traffic). Two cases have to be covered here (see also [GMPLS-ARCH]) since the secondary LSP are setup with resource pre-reservation but with or without label pre-selection (both allowing sharing of the recovery resources). In the former case (defined as the default), secondary LSP signaling does not necessitate any specific procedure compared to the one defined in [RFC-3473]. However, in the latter case, label (and thus resource) re-allocation MAY occur during the secondary LSP activation. This means that during the LSP activation phase, labels MAY be re-assigned (with higher precedence over existing label assignment, see also [RFC-3471]). 11. (Full) LSP Re-routing LSP re-routing, on the other hand, switches normal traffic to an alternate LSP that is fully established only after failure occurrence. The new (alternate) route is selected at the LSP head- end and may reuse intermediate nodes included in the original route; it may also include additional intermediate nodes. For strict-hop routing, TE requirements can be directly applied to the route computation, and the filed node or link can be avoided. However, if the failure occurred within a loose-routed hop, the head-end node may not have enough information to reroute the LSP around the failure. Crankback signaling and route exclusion techniques (see [XRO]) MAY be used in this case. The alternate route may be either computed on demand (that is, when the failure occurs; this is referred to as full LSP re-routing) or pre-computed and stored for use when the failure is reported. The latter offers faster restoration time. There is, however, a risk that the alternate route will become out of date through other changes in the network - this can be mitigated to some extent by periodic recalculation of idle alternate routes. (Full) LSP re-routing will be initiated by the head-end node that has either detected the failure or received a Notify message and/or J.P.Lang et al. - Internet Draft û Expires August 2004 19 draft-lang-ccamp-gmpls-recovery-e2e-signaling-03.txt February 2004 a PathErr message indicating that a failure has occurred. The new LSP resources can be established using the make-before-break mechanism, where the new LSP is setup before the old LSP is torn down. This is done by using the mechanisms of the SESSION object and the Shared-Explicit (SE) reservation style (see [RFC-3209]). Both the new and old LSPs can share resources at common nodes. Note that the make-before-break mechanism is not used to avoid disruption to the normal traffic flow (the latter has already been broken by the failure that is being repaired). However, it is valuable to retain the resources allocated on the original LSP that will be re-used by the new alternate LSP. 11.1 Identifiers The Tunnel End Point Address, Tunnel Id, Extended Tunnel Id, Tunnel Sender Address and LSP Id are all used to uniquely identify both the old and new LSPs. The new (alternate) LSP is setup before the old LSP is torn down using Shared-Explicit (SE) reservation style. This ensures that the new LSP is established without double counting resource requirements along common segments. Note: if the alternate LSP is setup before any failure occurrence with SE style resource reservation, the latter shares the same Tunnel End Point Address, Tunnel Id, Extended Tunnel Id, and Tunnel Sender Address with the original LSP (i.e. only the LSP Id value MUST be different). 11.2 Signaling Re-routable LSPs A new PROTECTION object is included in the Path message during signaling of dynamically re-routable LSPs, with the end-to-end LSP Protection Type value set to "Full Re-routing". These LSPs that can be either uni- or bi-directional are signaled by setting in this object the S bit to 0, the P bit to 0 and the Association ID to 0. Any specific action to be taken during the provisioning phase is up the end-node local policy. Note: when the end-to-end LSP Protection Type is set to "Unprotected", both S and P bit MUST be set to 0 and the LSP MUST NOT be re-routed at the head-end node after failure occurrence. The Association_ID value MUST be set to 0. 12. Reversion Reversion refers to a recovery switching operation, where the normal traffic returns to (or remains on) the working LSP when it has recovered from the failure. Reversion implies that resources remain allocated to the LSP that was originally routed over it even after a failure. It is important to have mechanisms that allow reversion to be performed with minimal service disruption and reconfiguration. J.P.Lang et al. - Internet Draft û Expires August 2004 20 draft-lang-ccamp-gmpls-recovery-e2e-signaling-03.txt February 2004 For "1+1 bi-directional" and "1:N Protection with Extra-traffic" protection, reversion to the recovered LSP occurs by using the following sequence: - first, clear the A bit of the ADMIN_STATUS object if set for the recovered LSP - then, apply the reverse 1-phase APS switchover request/response (or 2-phase APS) described in Section 6.2 (or Section 7.2, respectively) to switch normal traffic back from the protecting to the recovered LSP. This is performed by using the Notify message with a new Error Code indicating "(Working) LSP Recovered (Switchover Request)". The Notify Ack message MUST be sent to confirm the reception of the Notify message (see [RFC- 3473], Section 4.3). - finally, clear the O bit of the PROTECTION object sent over the protecting LSP. For "Re-routing without Extra-traffic" reversion (including the shared recovery case) implies that the formerly working LSP has not been torn down by the head-end node upon PathErr message reception (i.e. the head-end node kept refreshing the working LSP under failure condition). This ensures that the same resources are retrieved after reversion switching. Re-activation is performed using the following sequence: - first, clear the A bit of the ADMIN_STATUS object if set for the recovered LSP - then, apply the reverse 1-phase APS switchover request/response described in Section 6.2, to switch normal traffic back from the protecting to the recovered LSP. This is performed by using the Notify message with a new Error Code indicating "(Working) LSP Recovered (Switchover Request)". The Notify Ack message MUST be sent to confirm the reception of the Notify message (see [RFC- 3473], Section 4.3). - finally, de-activate the protecting LSP by setting the S bit to 1 in the PROTECTION object sent over the protecting LSP. 13. External Commands This section specifies the control plane behavior when using several external commands (see [TERM]), typically issued by an operator through the Network Management System (NMS)/Element Management System (EMS), which can be used to influence or command the recovery operations. Other specific commands may complete the below list. A. Lockout of recovery LSP: The Lockout bit (L bit) of the ADMIN_STATUS object is used following the rules defined in Section 8 of [RFC-3471] and Section 7 of [RFC- 3473]. The L bit must be set together with the Reflect (R) bit in the ADMIN_STATUS object sent in the Path message. Upon reception of the Resv message with the L bit set, this forces the recovery LSP to be temporarily unavailable to transport traffic (either normal or J.P.Lang et al. - Internet Draft û Expires August 2004 21 draft-lang-ccamp-gmpls-recovery-e2e-signaling-03.txt February 2004 extra traffic). Unlock is performed by clearing the L bit, following the rules defined in Section 7 of [RFC-3473]. B. Lockout of normal traffic: The O bit of the PROTECTION object is set to 1 to force the recovery LSP to be temporarily unavailable to transport normal traffic. This operation MUST never occur unless the working LSP is carrying the normal traffic. Unlock is performed by clearing the O bit over the protecting LSP. C. Forced switch for normal traffic: Recovery signaling is initiated externally that switches normal traffic to the recovery LSP following the procedures defined in Section 6, 7, 8 and 9. D. Manual switch for normal traffic: Recovery signaling operation is initiated externally that switches normal traffic to the recovery LSP following the procedures defined in Section 6, 7, 8 and 9. This, unless a fault condition exists on other LSPs/spans (including the recovery LSP) or an equal or higher priority switch command is in effect. E. Manual switch for recovery LSP: Recovery signaling operation is initiated externally that switches normal traffic to the working LSP following the procedure defined in Section 12. This, unless a fault condition exists on the working LSP or an equal or higher priority switch command is in effect. 14. PROTECTION Object In this section, we describe the extensions to the PROTECTION object to broaden its applicability to end-to-end LSP recovery. In addition to modifications to the format of the PROTECTION object, we extend its use so that the object can be included in the Notify message to act a switchover request for 1+1 bi-directional and 1:1 protection. The format of the PROTECTION Object (Class-Num = 37, C-Type = TBA by IANA) is 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Length | Class-Num(37) | C-Type (TBA) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |S|P|N|O| Reserved | LSP Flags | Reserved | Link Flags| +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Reserved | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ J.P.Lang et al. - Internet Draft û Expires August 2004 22 draft-lang-ccamp-gmpls-recovery-e2e-signaling-03.txt February 2004 Secondary (S): 1 bit When set to 1, this bit indicates that the requested LSP is a secondary LSP. When set to 0 (default), it indicates that the requested LSP is a primary LSP. Protecting (P): 1 bit When set to 1, this bit indicates that the requested LSP is a protecting LSP. When set to 0 (default), it indicates that the requested LSP is a working LSP. The combination, S set to 1 with P set to 0 is not valid. Notification (N): 1 bit When set to 1, this bit indicates that the control plane message exchange is only used for notification during protection switching. When set to 0 (default), it indicates that the control plane message exchanges are used for protection switching purposes. The N bit is only applicable when the LSP Flag is set to either 0x04, or 0x08 or 0x10. The N bit MUST be set to 0 in any other case. Operational (O): 1 bit When set to 1, this bit indicates that the protecting LSP is carrying the normal traffic after protection switching. The O bit is only applicable when the P bit is set to 1 and the LSP Flag is set to either 0x04, or 0x08 or 0x10. The O bit MUST be set to 0 in any other case. The O bit MUST be set to 0 in any other case. Reserved: 5 bits This field is reserved. It MUST be set to zero on transmission and MUST be ignored on receipt. These bits SHOULD be passed through unmodified by transit nodes. LSP (Protection Type) Flags: 6 bits Indicates the desired end-to-end LSP recovery type. A value of 0 implies that the LSP is "Unprotected". Only one value SHOULD be set at a time. The following values are defined. All other values are reserved. 0x00 Unprotected 0x01 (Full) Re-routing 0x02 Re-routing without Extra-Traffic 0x04 1:N Protection with Extra-Traffic 0x08 1+1 Unidirectional Protection 0x10 1+1 Bi-directional Protection J.P.Lang et al. - Internet Draft û Expires August 2004 23 draft-lang-ccamp-gmpls-recovery-e2e-signaling-03.txt February 2004 Reserved: 10 bits This field is reserved. It MUST be set to zero on transmission and MUST be ignored on receipt. These bits SHOULD be passed through unmodified by transit nodes. Link Flags: 6 bits Indicates the desired link protection type (see [RFC-3471]). Intermediate nodes processing a Path message containing a PROTECTION object with the LSP Protection Type "0x02" value set and a PRIMARY PATH ROUTE object (see Section 15) and MUST verify that the requested LSP Protection Type can be supported by the outgoing interface. If it can not, the node MUST generate a PathErr message, with a "Routing problem/Unsupported LSP Protection" indication. Intermediate and Egress nodes processing a Path message containing the PROTECTION object MUST verify that the requested LSP Protection Type can be satisfied by the incoming interface. If it cannot, the node MUST generate a PathErr message, with the "Routing problem/ Unsupported LSP Protection" error code. 15. PRIMARY PATH ROUTE Object The PRIMARY PATH ROUTE object (PPRO) is defined to inform nodes along the path of a secondary protecting LSP about which resources (link/nodes) are being used by the associated primary protected LSP (as specified by the Association ID field). This object MUST be present in the Path message (for the pre-provisioning of the secondary protecting LSP) if and only if the LSP Protection Type value is set to "0x02". This document does not assume or preclude any other usage for this object. PRIMARY PATH ROUTE objects carry information extracted from the EXPLICIT ROUTE object and/or the RECORD ROUTE object of the primary working LSPs they protect. Selection of the PPRO content is up to local policy of the head-end LSR that initiates the request. Therefore, the information included in these objects MAY be used as policy-based admission control to ensure that recovery resources are only shared between secondary protecting LSPs whose associated primary LSPs have link/node/SRLG disjoint paths. 15.1. Definition The primary path route is specified via the PRIMARY_PATH_ROUTE object (PPRO). The Primary Path Route Class Number is TBA by IANA. Currently one C-Type (Class-Type) is defined, Type 1 Primary Path Route. The PRIMARY_PATH_ROUTE object has the following format: Class-Num = TBA by IANA (of form 0bbbbbbb), C-Type = 1 (suggested) J.P.Lang et al. - Internet Draft û Expires August 2004 24 draft-lang-ccamp-gmpls-recovery-e2e-signaling-03.txt February 2004 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | | // (Subobjects) // | | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ The contents of a PRIMARY_PATH_ROUTE object are a series of variable-length data items called subobjects. The subobjects are identical to those that can constitute an EXPLICIT/RECORD ROUTE object as defined in [RFC-3209], [RFC-3473] and [RFC-3477]. To signal a secondary protecting LSP, the Path message MUST include at least one or MAY include multiple PRIMARY_PATH_ROUTE objects, where each object is meaningful. The latter is useful when a given secondary protecting LSP must be link/node/SRLG disjoint from more than one primary LSP (i.e. is protecting more than one primary LSP). 15.2 Applicability The PRIMARY_PATH_ROUTE object MUST only be used when all GMPLS nodes along the path support the PRIMARY_PATH_ROUTE object and a secondary protecting LSP is being requested. The PRIMARY_PATH_ROUTE object is assigned a class value of the form 0bbbbbbb. Receiving GMPLS nodes along the path that do not support this object MUST return a PathErr message with the "Unknown Object Class" error code. Also, the following restrictions MUST be applied with respect to the PPRO usage: - PPROs MUST only be sent over secondary protecting LSPs (S bit = 1 and P bit = 1) and when the LSP Protection Type value is set to "0x02" in the PROTECTION object (see Section 14.) - Crossed exchanges of PPROs over primary LSPs are forbidden (i.e. their usage is restricted to a single set of protected LSPs). If a PPRO is received with the S bit set to 0 in the PROTECTION object, the receiving node MUST return a PathErr with the "Routing Problem/PRIMARY PATH_ROUTE object not applicable" error code. - The PPRO's content MUST NOT include subobjects coming from other PPROs. In particular, received PPROs MUST NOT be re-used to establish other working or protecting LSPs. 15.3 Subobjects The PRIMAY_PATH_ROUTE object is defined as a list of variable-length data items called subobjects. PPR subobjects are derived from the subobjects of the EXPLICIT ROUTE and/or RECORD ROUTE object of the J.P.Lang et al. - Internet Draft û Expires August 2004 25 draft-lang-ccamp-gmpls-recovery-e2e-signaling-03.txt February 2004 primary working LSP(s). Each PPR subobject has its own length field. The length contains the total length of the subobject in bytes, including the Type and Length fields. The length MUST always be a multiple of 4, and at least 4. The following subobjects are currently defined for the PRIMARY PATH ROUTE object: - Sub-Type 1: IPv4 Address (see [RFC 3209]) - Sub-Type 2: IPv6 Address (see [RFC 3209]) - Sub-Type 3: Label (see [RFC-3473]) - Sub-Type 4: Unnumbered Interface (see [RFC-3477]) An empty PPRO with no subobjects is considered as illegal. If there is no first subobject, the corresponding Path message is also in error and the receiving node SHOULD return a PathErr with the "Routing Problem/Bad PRIMARY PATH_ROUTE object" error code. Note: an intermediate node processing a PPRO can derive SRLG identifiers from the local IGP-TE database using its Type 1, 2 or 4 subobject values as pointers to the corresponding TE Links (assuming each of them has an associated SRLG TE attribute). 15.4 Processing The PPRO enables of sharing recovery resources between a given secondary protecting LSP and one or more secondary protecting LSPs if their corresponding primary working LSPs have mutually (link/node/SRLG) disjoint paths. Consider a node N through which n secondary protecting LSPs (say P[1],...,P[n]) have already been established and protecting n primary working LSPs (say P'[1],...,P'[n]). Suppose also that these n secondary working LSPs share a given outgoing link resource (say r). Now, suppose that node N receives a Path message for an additional secondary protecting LSP (say Q, protecting Q'). The PPRO carried by this Path messages is processed as follows: - N checks whether the primary working LSPs P'[1],...,P'[n] associated with the LSPs P[1],...,P[n] respectively have any link, node and SLRG in common with the primary working Q' (associated with Q) by comparing the stored PPRO subobjects associated with P'[1],...,P'[n] with the PPRO subobjects associated with Q' received in the Path message. - If this is the case, N SHOULD NOT attempt to share the outgoing link resource r between P[1],...,P[n] and Q. However, upon local policy decision, N MAY allocate another available (shared) link other than r for use by Q. If this is not the case (upon the local policy decision that no other link is allowed to be allocated for Q) or if no other link is available for Q, N SHOULD return a PathErr message with the "Admission Control Failure/LSP Admission J.P.Lang et al. - Internet Draft û Expires August 2004 26 draft-lang-ccamp-gmpls-recovery-e2e-signaling-03.txt February 2004 Failure" error code. - Otherwise (if P'[1],...,P'[n] and Q' are fully disjoint), the link r selected by N for the LSP Q MAY be exactly the same as the one selected for the LSPs P[1],...,P[n]. This, after verifying (also from its local policy) that the selected link r can be shared between these LSPs. If this is not the case (for instance, the sharing ratio has reached its maximum for that link) and upon local policy decision no other link is allowed to be allocated for Q, N SHOULD return a PathErr with the "Admission Control Failure/ Requested Bandwidth Unavailable" error code. Otherwise (if no other link is available), N SHOULD return a PathErr with the "Admission Control Failure/LSP Admission Failure" error code. Note that the process, through which m out of the n (m =< n) secondary protecting LSPs PPROs may be selected on a local basis to perform the above comparison and subsequent link selection, is out of scope of this document. 16. ASSOCIATION Object The ASSOCIATION object is used to associate LSPs with each other. In the context of end-to-end LSP recovery, the association MUST only identify LSPs that support the same Tunnel ID. The Association Type, Association Source and Association ID fields of the object together uniquely identify an association. The object uses an object class number of the form 11bbbbbb to ensure compatibility with non- supporting nodes. The ASSOCIATION object is used to associate LSPs with each other. 16.1. Format The IPv4 Association object has the format: 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(TBD)| C-Type (1) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Association Type | Association ID | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | IPv4 Association Source | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ The IPv6 Association object has the format: 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(TBD)| C-Type (2) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ J.P.Lang et al. - Internet Draft û Expires August 2004 27 draft-lang-ccamp-gmpls-recovery-e2e-signaling-03.txt February 2004 | Association Type | Association ID | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | | | IPv6 Association Source | | | | | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Association Type: 16 bits Indicates the type of association being identified. Note that this value is considered when determining association. The following are values defined in this document. Value Type ----- ---- 0 Reserved 1 Recovery (R) Association ID: 16 bits A value that when combined with Association Type and Association Source uniquely identifies an association. Association Source: 4 or 16 bytes The IP address of the node that originated the association. 16.2. Processing The ASSOCIATION object is used to associate different LSPs with each other. In the protection and restoration context, the object is used to associate a recovery LSP with the LSP it is protecting. The object is carried in Path messages. More than one object may be carried in a single Path message. Transit nodes MUST transmit, without modification, any received ASSOCIATION object in the corresponding outgoing Path message. An ASSOCIATION object with an Association Type set to the value Recovery is used to identify a LSP Recovery related association. Any node associating a recovery LSP MUST insert an ASSOCIATION object with a Recovery Association Type set in the Path message of the recovery LSP. The Association Source MUST be set to the tunnel sender address of the LSP being protected. The Association ID MUST be set to the LSP ID of the LSP being protected by this LSP or the LSP protecting this LSP. If unknown, this value is set to 0 (default). Also, the value of the Association ID MAY change during the lifetime of the LSP. Nodes merging recovery LSPs use received ASSOCIATION objects with the Recovery type to associate a recovery LSP with it's matching J.P.Lang et al. - Internet Draft û Expires August 2004 28 draft-lang-ccamp-gmpls-recovery-e2e-signaling-03.txt February 2004 working LSP. This information is used to bind the appropriate working and recovery LSPs together. 17. Updated RSVP Message Formats This section presents the RSVP message related formats as modified by this document. Unmodified RSVP message formats are not listed. The format of a Path message is as follows: ::= [ ] [ [ | ] ... ] [ ] [ ] [ ] [ ... ] [ ] [ ... ] [ ] [ ... ] [ ... ] [ ... ] The format of the for unidirectional and bidirectional LSPs is not modified by the present document 18. Security Considerations This document does not introduce or imply any specific security consideration. 19. Acknowledgments The authors would like to thank John Drake for its active collaboration, Adrian Farrel for his contribution to this document (in particular, to the Section 11) and his thorough review of the document, Bart Rousseau (for editorial review) and Stefaan De_Cnodder. The authors would like also to thank Lou Berger for the time and effort he spent together with the design team, in contributing to the present document. 20. IANA Considerations IANA assigns values to RSVP protocol parameters. Within the current document a PROTECTION object (new C-Type) and a PRIMARY PATH ROUTE object are defined. J.P.Lang et al. - Internet Draft û Expires August 2004 29 draft-lang-ccamp-gmpls-recovery-e2e-signaling-03.txt February 2004 One RSVP Class Number (Class-Num) and two Class Types (C-Types) values have to be defined by IANA in registry: http://www.iana.org/assignments/rsvp-parameters - PROTECTION object: Class-Num = 37, C-Type = 2 (suggested) - PRIMARY PATH ROUTE object: Class-Num = TBA (of form 0bbbbbbb), C-Type = 1 (suggested) - ASSOCIATION object: Class-Num = TBA (of form 11bbbbbb), C-Type = 1 (suggested) - Error values: o "Admission Control Failure/LSP Admission Failure" (value = TBA) o "Routing Problem/Unsupported LSP Protection" (value = TBA) o "Routing Problem/Bad PRIMARY PATH_ROUTE object" (value = TBA) o "Routing Problem/PRIMARY PATH_ROUTE object not applicable" (value = TBA) o "Notify Error/LSP Failure" (value = TBA) o "Notify Error/LSP Recovered" (value = TBA) 21. Intellectual Property Considerations This section is taken from Section 10.4 of [RFC2026]. The IETF takes no position regarding the validity or scope of any intellectual property 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; neither does it represent that it has made any effort to identify any such rights. Information on the IETF's procedures with respect to rights in standards-track and standards-related documentation can be found in BCP-11. Copies of claims of rights made available for publication 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 implementors or users of this specification can be obtained from the IETF Secretariat. The IETF invites any interested party to bring to its attention any copyrights, patents or patent applications, or other proprietary rights, which may cover technology that may be required to practice this standard. Please address the information to the IETF Executive Director. J.P.Lang et al. - Internet Draft û Expires August 2004 30 draft-lang-ccamp-gmpls-recovery-e2e-signaling-03.txt February 2004 22. References 22.1 Normative References [FRR] P.Pan (Editor), "Fast Reroute Extensions to RSVP-TE for LSP Tunnels," Internet Draft, Work in progress, draft- ietf-mpls-rsvp-lsp-fastreroute-03.txt, June 2003. [FUNCT] J.P.Lang and B.Rajagopalan (Editors), "Generalized MPLS Recovery Functional Specification," Internet Draft, Work in Progress, draft-ietf-ccamp-gmpls-recovery- functional-01.txt, September 2003. [GMPLS-ARCH] E.Mannie (Editor), "Generalized Multi-Protocol Label Switching Architecture," Internet Draft, Work in progress, draft-ietf-ccamp-gmpls-architecture-07.txt, May 2003. [GMPLS-RTG] K.Kompella (Editor), "Routing Extensions in Support of Generalized MPLS," Internet Draft, Work in Progress, draft-ietf-ccamp-gmpls-routing-09.txt, October 2003. [LMP] J.Lang (Editor), "Link Management Protocol (LMP) v1.0," Internet Draft, Work in progress, draft-ietf-ccamp-lmp- 10, October 2003. [RFC-2026] S.Bradner, "The Internet Standards Process -- Revision 3," BCP 9, RFC 2026, October 1996. [RFC-2119] S.Bradner, "Key words for use in RFCs to Indicate Requirement Levels," BCP 14, RFC 2119, March 1997. [RFC-2961] L.Berger et al., "RSVP Refresh Overhead Reduction Extensions," RFC 2961, April 2001. [RFC-3209] D.Awduche et al., "RSVP-TE: Extensions to RSVP for LSP Tunnels," RFC 3209, December 2001. [RFC-3471] L.Berger (Editor) et al., "Generalized Multi-Protocol Label Switching (GMPLS) û Signaling Functional Description," RFC 3471, January 2003. [RFC-3473] L.Berger (Editor) et al., "Generalized Multi-Protocol Label Switching (GMPLS) Signaling û Resource Reservation Protocol - Traffic Engineering (RSVP-TE) Extensions," RFC 3473, January 2003. [RFC-3477] K.Kompella, and Y.Rekhter, "Signalling Unnumbered Links in Resource Reservation Protocol - Traffic Engineering (RSVP-TE)," RFC 3477, January 2003. J.P.Lang et al. - Internet Draft û Expires August 2004 31 draft-lang-ccamp-gmpls-recovery-e2e-signaling-03.txt February 2004 [TERM] E.Mannie and D.Papadimitriou (Editors), "Recovery (Protection and Restoration) Terminology for GMPLS," Internet Draft, Work in progress, draft-ietf-ccamp- gmpls-recovery-terminology-03.txt, January 2004. [XRO] C.Y.Lee et al. "Exclude Routes - Extension to RSVP-TE," Internet Draft, Work in progress, draft-ietf-ccamp- rsvp-te-exclude-route-01.txt, November 2003. 23. Author's Addresses Jonathan Lang (Rincon Networks) E-mail: jplang@ieee.org Yakov Rekhter (Juniper) 1194 N. Mathilda Avenue Sunnyvale, CA 94089, USA E-mail: yakov@juniper.net Dimitri Papadimitriou (Alcatel) Fr. Wellesplein, 1 B-2018, Antwerpen, Belgium E-mail: dimitri.papadimitriou@alcatel.be J.P.Lang et al. - Internet Draft û Expires August 2004 32 draft-lang-ccamp-gmpls-recovery-e2e-signaling-03.txt February 2004 Full Copyright Statement "Copyright (C) The Internet Society (date). All Rights Reserved. This document and translations of it may be copied and furnished to others, and derivative works that comment on or otherwise explain it or assist in its implementation may be prepared, copied, published and distributed, in whole or in part, without restriction of any kind, provided that the above copyright notice and this paragraph are included on all such copies and derivative works. However, this document itself may not be modified in any way, such as by removing the copyright notice or references to the Internet Society or other Internet organizations, except as needed for the purpose of developing Internet standards in which case the procedures for copyrights defined in the Internet Standards process must be followed, or as required to translate it into languages other than English. The limited permissions granted above are perpetual and will not be revoked by the Internet Society or its successors or assigns. This document and the information contained herein is provided on an "AS IS" basis and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING TASK FORCE DISCLAIMS 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." J.P.Lang et al. - Internet Draft û Expires August 2004 33