Network Working Group L. Berger, Editor Request for Comments: 3473 Movaz Networks Category: Standards Track January 2003 Generalized Multi-Protocol Label Switching (GMPLS) Signaling Resource ReserVation Protocol-Traffic Engineering (RSVP-TE) Extensions 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 Internet Society (2003). All Rights Reserved. Abstract This document describes extensions to Multi-Protocol Label Switching (MPLS) Resource ReserVation Protocol - Traffic Engineering (RSVP-TE) signaling required to support Generalized MPLS. Generalized MPLS extends the MPLS control plane to encompass time-division (e.g., Synchronous Optical Network and Synchronous Digital Hierarchy, SONET/SDH), wavelength (optical lambdas) and spatial switching (e.g., incoming port or fiber to outgoing port or fiber). This document presents a RSVP-TE specific description of the extensions. A generic functional description can be found in separate documents. Table of Contents 1. Introduction .............................................. 2 2. Label Related Formats .................................... 3 2.1 Generalized Label Request Object ........................ 3 2.2 Bandwidth Encoding ...................................... 4 2.3 Generalized Label Object ................................ 5 2.4 Waveband Switching ...................................... 5 2.5 Suggested Label ......................................... 6 2.6 Label Set ............................................... 7 3. Bidirectional LSPs ........................................ 8 3.1 Procedures .............................................. 9 3.2 Contention Resolution ................................... 9 4. Notification .............................................. 9 4.1 Acceptable Label Set Object ............................. 10 4.2 Notify Request Objects .................................. 10 Berger Standards Track [Page 1] RFC 3473 GMPLS Signaling - RSVP-TE Extensions January 2003 4.3 Notify Message .......................................... 12 4.4 Removing State with a PathErr message ................... 14 5. Explicit Label Control .................................... 15 5.1 Label ERO subobject ..................................... 15 5.2 Label RRO subobject ..................................... 16 6. Protection Object ......................................... 17 6.1 Procedures .............................................. 18 7. Administrative Status Information ......................... 18 7.1 Admin Status Object ..................................... 18 7.2 Path and Resv Message Procedures ........................ 18 7.3 Notify Message Procedures ............................... 20 8. Control Channel Separation ................................ 21 8.1 Interface Identification ................................ 21 8.2 Errored Interface Identification ........................ 23 9. Fault Handling ............................................ 25 9.1 Restart_Cap Object ...................................... 25 9.2 Processing of Restart_Cap Object ........................ 26 9.3 Modification to Hello Processing to Support State Recovery .......................................... 26 9.4 Control Channel Faults .................................. 27 9.5 Nodal Faults ............................................ 27 10. RSVP Message Formats and Handling ......................... 30 10.1 RSVP Message Formats ................................... 30 10.2 Addressing Path and PathTear Messages ................. 32 11. Acknowledgments ........................................... 32 12. Security Considerations ................................... 33 13. IANA Considerations ....................................... 34 13.1 IANA Assignments ....................................... 35 14. Intellectual Property Considerations ...................... 36 15. References ................................................ 37 15.1 Normative References ................................... 37 15.2 Informative References ................................. 38 16. Contributors .............................................. 38 17. Editor's Address .......................................... 41 18. Full Copyright Statement .................................. 42 1. Introduction Generalized MPLS extends MPLS from supporting packet (PSC) interfaces and switching to include support of three new classes of interfaces and switching: Time-Division Multiplex (TDM), Lambda Switch (LSC) and Fiber-Switch (FSC). A functional description of the extensions to MPLS signaling needed to support the new classes of interfaces and switching is provided in [RFC3471]. This document presents RSVP-TE specific formats and mechanisms needed to support all four classes of interfaces. Berger Standards Track [Page 2] RFC 3473 GMPLS Signaling - RSVP-TE Extensions January 2003 [RFC3471] should be viewed as a companion document to this document. The format of this document parallels [RFC3471]. In addition to the other features of Generalized MPLS, this document also defines RSVP- TE specific features to support rapid failure notification, see Sections 4.2 and 4.3. 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]. 2. Label Related Formats This section defines formats for a generalized label request, a generalized label, support for waveband switching, suggested label and label sets. 2.1. Generalized Label Request Object A Path message SHOULD contain as specific an LSP (Label Switched Path) Encoding Type as possible to allow the maximum flexibility in switching by transit LSRs. A Generalized Label Request object is set by the ingress node, transparently passed by transit nodes, and used by the egress node. The Switching Type field may also be updated hop-by-hop. The format of a Generalized Label Request object is: 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 (19)| C-Type (4) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | LSP Enc. Type |Switching Type | G-PID | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ See [RFC3471] for a description of parameters. 2.1.1. Procedures A node processing a Path message containing a Generalized Label Request must verify that the requested parameters can be satisfied by the interface on which the incoming label is to be allocated, the node itself, and by the interface on which the traffic will be transmitted. The node may either directly support the LSP or it may use a tunnel (FA), i.e., another class of switching. In either case, each parameter must be checked. Berger Standards Track [Page 3] RFC 3473 GMPLS Signaling - RSVP-TE Extensions January 2003 Note that local node policy dictates when tunnels may be used and when they may be created. Local policy may allow for tunnels to be dynamically established or may be solely administratively controlled. For more information on tunnels and processing of ER hops when using tunnels see [MPLS-HIERARCHY]. Transit and egress nodes MUST verify that the node itself and, where appropriate, that the interface or tunnel on which the traffic will be transmitted can support the requested LSP Encoding Type. If encoding cannot be supported, the node MUST generate a PathErr message, with a "Routing problem/Unsupported Encoding" indication. Nodes MUST verify that the type indicated in the Switching Type parameter is supported on the corresponding incoming interface. If the type cannot be supported, the node MUST generate a PathErr message with a "Routing problem/Switching Type" indication. The G-PID parameter is normally only examined at the egress. If the indicated G-PID cannot be supported then the egress MUST generate a PathErr message, with a "Routing problem/Unsupported L3PID" indication. In the case of PSC and when penultimate hop popping (PHP) is requested, the penultimate hop also examines the (stored) G-PID during the processing of the Resv message. In this case if the G-PID is not supported, then the penultimate hop MUST generate a ResvErr message with a "Routing problem/Unacceptable label value" indication. The generated ResvErr message MAY include an Acceptable Label Set, see Section 4.1. When an error message is not generated, normal processing occurs. In the transit case this will typically result in a Path message being propagated. In the egress case and PHP special case this will typically result in a Resv message being generated. 2.2. Bandwidth Encoding Bandwidth encodings are carried in the SENDER_TSPEC and FLOWSPEC objects. See [RFC3471] for a definition of values to be used for specific signal types. These values are set in the Peak Data Rate field of Int-Serv objects, see [RFC2210]. Other bandwidth/service related parameters in the object are ignored and carried transparently. Berger Standards Track [Page 4] RFC 3473 GMPLS Signaling - RSVP-TE Extensions January 2003 2.3. Generalized Label Object The format of a Generalized Label object is: 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 (16)| C-Type (2) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Label | | ... | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ See [RFC3471] for a description of parameters and encoding of labels. 2.3.1. Procedures The Generalized Label travels in the upstream direction in Resv messages. The presence of both a generalized and normal label object in a Resv message is a protocol error and should treated as a malformed message by the recipient. The recipient of a Resv message containing a Generalized Label verifies that the values passed are acceptable. If the label is unacceptable then the recipient MUST generate a ResvErr message with a "Routing problem/MPLS label allocation failure" indication. 2.4. Waveband Switching Object Waveband switching uses the same format as the generalized label, see section 2.2. Waveband Label uses C-Type (3), In the context of waveband switching, the generalized label has the following format: Berger Standards Track [Page 5] RFC 3473 GMPLS Signaling - RSVP-TE Extensions January 2003 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 (16)| C-Type (3) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Waveband Id | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Start Label | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | End Label | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ See [RFC3471] for a description of parameters. 2.4.1. Procedures The procedures defined in Section 2.3.1 apply to waveband switching. This includes generating a ResvErr message with a "Routing problem/MPLS label allocation failure" indication if any of the label fields are unrecognized or unacceptable. Additionally, when a waveband is switched to another waveband, it is possible that the wavelengths within the waveband will be mirrored about a center frequency. When this type of switching is employed, the start and end label in the waveband label object MUST be flipped before forwarding the label object with the new waveband Id. In this manner an egress/ingress LSR which receives a waveband label which has these values inverted, knows that it must also invert its egress association to pick up the proper wavelengths. This operation MUST be performed in both directions when a bidirectional waveband tunnel is being established. 2.5. Suggested Label Object The format of a Suggested_Label object is identical to a generalized label. It is used in Path messages. A Suggested_Label object uses Class-Number 129 (of form 10bbbbbb) and the C-Type of the label being suggested. Errors in received Suggested_Label objects MUST be ignored. This includes any received inconsistent or unacceptable values. Per [RFC3471], if a downstream node passes a label value that differs from the suggested label upstream, the upstream LSR MUST either reconfigure itself so that it uses the label specified by the downstream node or generate a ResvErr message with a "Routing Berger Standards Track [Page 6] RFC 3473 GMPLS Signaling - RSVP-TE Extensions January 2003 problem/Unacceptable label value" indication. Furthermore, an ingress node SHOULD NOT transmit data traffic using a suggested label until the downstream node passes a corresponding label upstream. 2.6. Label Set Object The Label_Set object uses Class-Number 36 (of form 0bbbbbbb) and the C-Type of 1. It is used in Path messages. The format of a Label_Set is: 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 (36)| C-Type (1) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Action | Reserved | Label Type | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Subchannel 1 | | ... | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ : : : : : : +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Subchannel N | | ... | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Label Type: 14 bits Indicates the type and format of the labels carried in the object. Values match the C-Type of the appropriate RSVP_LABEL object. Only the low order 8 bits are used in this field. See [RFC3471] for a description of other parameters. 2.6.1. Procedures A Label Set is defined via one or more Label_Set objects. Specific labels/subchannels can be added to or excluded from a Label Set via Action zero (0) and one (1) objects respectively. Ranges of labels/subchannels can be added to or excluded from a Label Set via Action two (2) and three (3) objects respectively. When the Label_Set objects only list labels/subchannels to exclude, this implies that all other labels are acceptable. Berger Standards Track [Page 7] RFC 3473 GMPLS Signaling - RSVP-TE Extensions January 2003 The absence of any Label_Set objects implies that all labels are acceptable. A Label Set is included when a node wishes to restrict the label(s) that may be used downstream. On reception of a Path message, the receiving node will restrict its choice of labels to one which is in the Label Set. Nodes capable of performing label conversion may also remove the Label Set prior to forwarding the Path message. If the node is unable to pick a label from the Label Set or if there is a problem parsing the Label_Set objects, then the request is terminated and a PathErr message with a "Routing problem/Label Set" indication MUST be generated. It is a local matter if the Label Set is stored for later selection on the Resv or if the selection is made immediately for propagation in the Resv. On reception of a Path message, the Label Set represented in the message is compared against the set of available labels at the downstream interface and the resulting intersecting Label Set is forwarded in a Path message. When the resulting Label Set is empty, the Path must be terminated, and a PathErr message, and a "Routing problem/Label Set" indication MUST be generated. Note that intersection is based on the physical labels (actual wavelength/band values) which may have different logical values on different links, as a result it is the responsibility of the node to map these values so that they have a consistent physical meaning, or to drop the particular values from the set if no suitable logical label value exists. When processing a Resv message at an intermediate node, the label propagated upstream MUST fall within the Label Set. Note, on reception of a Resv message a node that is incapable of performing label conversion has no other choice than to use the same physical label (wavelength/band) as received in the Resv message. In this case, the use and propagation of a Label Set will significantly reduce the chances that this allocation will fail. 3. Bidirectional LSPs Bidirectional LSP setup is indicated by the presence of an Upstream Label in the Path message. An Upstream_Label object has the same format as the generalized label, see Section 2.3. The Upstream_Label object uses Class-Number 35 (of form 0bbbbbbb) and the C-Type of the label being used. Berger Standards Track [Page 8] RFC 3473 GMPLS Signaling - RSVP-TE Extensions January 2003 3.1. Procedures The process of establishing a bidirectional LSP follows the establishment of a unidirectional LSP with some additions. To support bidirectional LSPs an Upstream_Label object is added to the Path message. The Upstream_Label object MUST indicate a label that is valid for forwarding at the time the Path message is sent. When a Path message containing an Upstream_Label object is received, the receiver first verifies that the upstream label is acceptable. If the label is not acceptable, the receiver MUST issue a PathErr message with a "Routing problem/Unacceptable label value" indication. The generated PathErr message MAY include an Acceptable Label Set, see Section 4.1. An intermediate node must also allocate a label on the outgoing interface and establish internal data paths before filling in an outgoing upstream label and propagating the Path message. If an intermediate node is unable to allocate a label or internal resources, then it MUST issue a PathErr message with a "Routing problem/MPLS label allocation failure" indication. Terminator nodes process Path messages as usual, with the exception that the upstream label can immediately be used to transport data traffic associated with the LSP upstream towards the initiator. When a bidirectional LSP is removed, both upstream and downstream labels are invalidated and it is no longer valid to send data using the associated labels. 3.2. Contention Resolution There are two additional contention resolution related considerations when controlling bidirectional LSP setup via RSVP-TE. The first is that for the purposes of RSVP contention resolution, the node ID is the IP address used in the RSVP_HOP object. The second is that a neighbor's node ID might not be known when sending an initial Path message. When this case occurs, a node should suggest a label chosen at random from the available label space. 4. Notification This section covers several notification related extensions. The first extension defines the Acceptable Label Set object to support Notification on Label Error, per [RFC3471]. The second and third extensions enable expedited notification of failures and other events to nodes responsible for restoring failed LSPs. (The second extension, the Notify Request object, identifies where event Berger Standards Track [Page 9] RFC 3473 GMPLS Signaling - RSVP-TE Extensions January 2003 notifications are to be sent. The third extension, the Notify message, provides for general event notification.) The final notification related extension allows for the removal of Path state on handling of PathErr messages. 4.1. Acceptable Label Set Object Acceptable_Label_Set objects use a Class-Number 130 (of form 10bbbbbb). The remaining contents of the object, including C-Type, have the identical format as the Label_Set object, see Section 2.6. Acceptable_Label_Set objects may be carried in PathErr and ResvErr messages. The procedures for defining an Acceptable Label Set follow the procedures for defining a Label Set, see Section 2.6.1. Specifically, an Acceptable Label Set is defined via one or more Acceptable_Label_Set objects. Specific labels/subchannels can be added to or excluded from an Acceptable Label Set via Action zero (0) and one (1) objects respectively. Ranges of labels/subchannels can be added to or excluded from an Acceptable Label Set via Action two (2) and three (3) objects respectively. When the Acceptable_Label_Set objects only list labels/subchannels to exclude, this implies that all other labels are acceptable. The inclusion of Acceptable_Label_Set objects is optional. If included, the PathErr or ResvErr message SHOULD contain a "Routing problem/Unacceptable label value" indication. The absence of Acceptable_Label_Set objects does not have any specific meaning. 4.2. Notify Request Objects Notifications may be sent via the Notify message defined below. The Notify Request object is used to request the generation of notifications. Notifications, i.e., the sending of a Notify message, may be requested in both the upstream and downstream directions. 4.2.1. Required Information The Notify Request Object may be carried in Path or Resv Messages, see Section 7. The Notify_Request Class-Number is 195 (of form 11bbbbbb). The format of a Notify Request is: o IPv4 Notify Request Object Berger Standards Track [Page 10] RFC 3473 GMPLS Signaling - RSVP-TE Extensions January 2003 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 (1) | C-Type (1) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | IPv4 Notify Node Address | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ IPv4 Notify Node Address: 32 bits The IP address of the node that should be notified when generating an error message. o IPv6 Notify Request Object 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 (2) | C-Type (2) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | | | IPv6 Notify Node Address | | | | | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ IPv6 Notify Node Address: 16 bytes The IP address of the node that should be notified when generating an error message. 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. 4.2.2. Procedures A Notify Request object may be inserted in Path or Resv messages to indicate the address of a node that should be notified of an LSP failure. As previously mentioned, notifications may be requested in both the upstream and downstream directions. Upstream notification is indicated via the inclusion of a Notify Request Object in the corresponding Path message. Downstream notification is indicated via the inclusion of a Notify Request Object in the corresponding Resv message. Berger Standards Track [Page 11] RFC 3473 GMPLS Signaling - RSVP-TE Extensions January 2003 A node receiving a message containing a Notify Request object SHOULD store the Notify Node Address in the corresponding state block. If the node is a transit node, it SHOULD also included a Notify Request object in the outgoing Path or Resv message. The outgoing Notify Node Address MAY be updated based on local policy. Note that the inclusion of a Notify Request object does not guarantee that a Notify message will be generated. 4.3. Notify Message The Notify message provides a mechanism to inform non-adjacent nodes of LSP related events. Notify messages are normally generated only after a Notify Request object has been received. The Notify message differs from the currently defined error messages (i.e., PathErr and ResvErr messages) in that it can be "targeted" to a node other than the immediate upstream or downstream neighbor and that it is a generalized notification mechanism. The Notify message does not replace existing error messages. The Notify message may be sent either (a) normally, where non-target nodes just forward the Notify message to the target node, similar to ResvConf processing in [RFC2205]; or (b) encapsulated in a new IP header whose destination is equal to the target IP address. Regardless of the transmission mechanism, nodes receiving a Notify message not destined to the node forward the message, unmodified, towards the target. To support reliable delivery of the Notify message, an Ack Message [RFC2961] is used to acknowledge the receipt of a Notify Message. See [RFC2961] for details on reliable RSVP message delivery. 4.3.1. Required Information The Notify message is a generalized notification message. The IP destination address is set to the IP address of the intended receiver. The Notify message is sent without the router alert option. A single Notify message may contain notifications being sent, with respect to each listed session, both upstream and downstream. The Notify message has a Message Type of 21. The Notify message format is as follows: ::= [] [ [ | ] ... ] [ ] Berger Standards Track [Page 12] RFC 3473 GMPLS Signaling - RSVP-TE Extensions January 2003 ::= [ ] | ::= [ ] [...] ::= [...] The ERROR_SPEC object specifies the error and includes the IP address of either the node that detected the error or the link that has failed. See ERROR_SPEC definition in [RFC2205]. The MESSAGE_ID and related objects are defined in [RFC2961] and are used when [RFC2961] is supported. 4.3.2. Procedures Notify messages are most commonly generated at nodes that detect an error that will trigger the generation of a PathErr or ResvErr message. If a PathErr message is to be generated and a Notify Request object has been received in the corresponding Path message, then a Notify message destined to the recorded node SHOULD be generated. If a ResvErr message is to be generated and a Notify Request object has been received in the corresponding Resv message, then a Notify message destined to the recorded node SHOULD be generated. As previously mentioned, a single error may generate a Notify message in both the upstream and downstream directions. Note that a Notify message MUST NOT be generated unless an appropriate Notify Request object has been received. When generating Notify messages, a node SHOULD attempt to combine notifications being sent to the same Notify Node and that share the same ERROR_SPEC into a single Notify message. The means by which a node determines which information may be combined is implementation dependent. Implementations may use event, timer based or other approaches. If using a timer based approach, the implementation SHOULD allow the user to configure the interval over which notifications are combined. When using a timer based approach, a default "notification interval" of 1 ms SHOULD be used. Notify messages SHOULD be delivered using the reliable message delivery mechanisms defined in [RFC2961]. Upon receiving a Notify message, the Notify Node SHOULD send a corresponding Ack message. Berger Standards Track [Page 13] RFC 3473 GMPLS Signaling - RSVP-TE Extensions January 2003 4.4. Removing State with a PathErr message The PathErr message as defined in [RFC2205] is sent hop-by-hop to the source of the associated Path message. Intermediate nodes may inspect this message, but take no action upon it. In an environment where Path messages are routed according to an IGP and that route may change dynamically, this behavior is a fine design choice. However, when RSVP is used with explicit routes, it is often the case that errors can only be corrected at the source node or some other node further upstream. In order to clean up resources, the source must receive the PathErr and then either send a PathTear (or wait for the messages to timeout). This causes idle resources to be held longer than necessary and increases control message load. In a situation where the control plane is attempting to recover from a serious outage, both the message load and the delay in freeing resources hamper the ability to rapidly reconverge. The situation can be greatly improved by allowing state to be removed by intermediate nodes on certain error conditions. To facilitate this a new flag is defined in the ERROR_SPEC object. The two currently defined ERROR_SPEC objects (IPv4 and IPv6 error spec objects) each contain a one byte flag field. Within that field two flags are defined. This specification defines a third flag, 0x04, Path_State_Removed. The semantics of the Path_State_Removed flag are simply that the node forwarding the error message has removed the Path state associated with the PathErr. By default, the Path_State_Removed flag is always set to zero when generating or forwarding a PathErr message. A node which encounters an error MAY set this flag if the error results in the associated Path state being discarded. If the node setting the flag is not the session endpoint, the node SHOULD generate a corresponding PathTear. A node receiving a PathErr message containing an ERROR_SPEC object with the Path_State_Removed flag set MAY also remove the associated Path state. If the Path state is removed the Path_State_Removed flag SHOULD be set in the outgoing PathErr message. A node which does not remove the associated Path state MUST NOT set the Path_State_Removed flag. A node that receives an error with the Path_State_Removed flag set to zero MUST NOT set this flag unless it also generates a corresponding PathTear message. Note that the use of this flag does not result in any interoperability incompatibilities. Berger Standards Track [Page 14] RFC 3473 GMPLS Signaling - RSVP-TE Extensions January 2003 5. Explicit Label Control The Label ERO (Explicit Route Object) and RRO (Record Route Object) subobjects are defined to support Explicit Label Control. Note that the Label RRO subobject was defined in [RFC3209] and is being extended to support bidirectional LSPs. 5.1. Label ERO subobject The Label ERO 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 |U| Reserved | C-Type | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Label | | ... | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ See [RFC3471] for a description of L, U and Label parameters. Type 3 Label Length The Length contains the total length of the subobject in bytes, including the Type and Length fields. The Length is always divisible by 4. C-Type The C-Type of the included Label Object. Copied from the Label Object. 5.1.1. Procedures The Label subobject follows a subobject containing the IP address, or the interface identifier [RFC3477], associated with the link on which it is to be used. Up to two label subobjects may be present, one for the downstream label and one for the upstream label. The following SHOULD result in "Bad EXPLICIT_ROUTE object" errors: o If the first label subobject is not preceded by a subobject containing an IP address, or an interface identifier [RFC3477], associated with an output link. Berger Standards Track [Page 15] RFC 3473 GMPLS Signaling - RSVP-TE Extensions January 2003 o For a label subobject to follow a subobject that has the L-bit set o On unidirectional LSP setup, for there to be a label subobject with the U-bit set o For there to be two label subobjects with the same U-bit values To support the label subobject, a node must check to see if the subobject following its associate address/interface is a label subobject. If it is, one subobject is examined for unidirectional LSPs and two subobjects for bidirectional LSPs. If the U-bit of the subobject being examined is clear (0), then value of the label is copied into a new Label_Set object. This Label_Set object MUST be included on the corresponding outgoing Path message. If the U-bit of the subobject being examined is set (1), then value of the label is label to be used for upstream traffic associated with the bidirectional LSP. If this label is not acceptable, a "Bad EXPLICIT_ROUTE object" error SHOULD be generated. If the label is acceptable, the label is copied into a new Upstream_Label object. This Upstream_Label object MUST be included on the corresponding outgoing Path message. After processing, the label subobjects are removed from the ERO. Note an implication of the above procedures is that the label subobject should never be the first subobject in a newly received message. If the label subobject is the the first subobject an a received ERO, then it SHOULD be treated as a "Bad strict node" error. Procedures by which an LSR at the head-end of an LSP obtains the information needed to construct the Label subobject are outside the scope of this document. 5.2. Label RRO subobject The Label RRO 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Type | Length |U| Flags | C-Type | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Label | | ... | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ See [RFC3471] for a description of U and Label parameters. Berger Standards Track [Page 16] RFC 3473 GMPLS Signaling - RSVP-TE Extensions January 2003 Type 3 Label Length See [RFC3209]. Flags See [RFC3209]. C-Type The C-Type of the included Label Object. Copied from the Label Object. 5.2.1. Procedures Label RRO subobjects are included in RROs as described in [RFC3209]. The only modification to usage and processing from [RFC3209] is that when labels are recorded for bidirectional LSPs, label ERO subobjects for both downstream and upstream labels MUST be included. 6. Protection Object The use of the Protection Object is optional. The object is included to indicate specific protection attributes of an LSP. The Protection Object uses Class-Number 37 (of form 0bbbbbbb). The format of the Protection Object is: 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 (1) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |S| Reserved | Link Flags| +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ See [RFC3471] for a description of parameters. Berger Standards Track [Page 17] RFC 3473 GMPLS Signaling - RSVP-TE Extensions January 2003 6.1. Procedures Transit nodes processing a Path message containing a Protection Object MUST verify that the requested protection can be satisfied by the outgoing interface or tunnel (FA). If it cannot, the node MUST generate a PathErr message, with a "Routing problem/Unsupported Link Protection" indication. 7. Administrative Status Information Administrative Status Information is carried in the Admin_Status object. The object provides information related to the administrative state of a particular LSP. The information is used in two ways. In the first, the object is carried in Path and Resv messages to indicate the administrative state of an LSP. In the second, the object is carried in a Notification message to request that the ingress node change the administrative state of an LSP. 7.1. Admin Status Object The use of the Admin_Status Object is optional. It uses Class-Number 196 (of form 11bbbbbb). The format of the Admin_Status Object is: 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(196)| C-Type (1) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |R| Reserved |T|A|D| +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ See [RFC3471] for a description of parameters. 7.2. Path and Resv Message Procedures The Admin_Status object is used to notify each node along the path of the status of the LSP. Status information is processed by each node based on local policy and then propagated in the corresponding outgoing messages. The object may be inserted in either Path or Resv messages at the discretion of the ingress (for Path messages) or egress (for Resv messages) nodes. The absence of the object is equivalent to receiving an object containing values all set to zero (0). Berger Standards Track [Page 18] RFC 3473 GMPLS Signaling - RSVP-TE Extensions January 2003 Transit nodes receiving a non-refresh Path or Resv message containing an Admin_Status object, update their local state, take any appropriate local action based on the indicated status and then propagate the received Admin_Status object in the corresponding outgoing Path or Resv message. If the values of an Admin_Status object received in a Resv message differs from the values received in a Path message then, with one exception, no local action should be taken but the values should still be propagated. The one case where values received in the Resv message should result in local action is when both the received R and D bits are set, i.e., are one (1). Edge nodes receiving a non-refresh Path or Resv message containing an Admin_Status object, also update their local state and take any appropriate local action based on the indicated status. When an Admin Status object is received with the R bit set, the receiving edge node should reflect the received values in a corresponding outgoing message. Specifically, if an egress node receives a Path message with the R bit of the Admin_Status object set and the node has previously issued a Resv message corresponding to the Path message, the node SHOULD send an updated Resv message containing an Admin_Status object with the same values set, with the exception of the R bit, as received in the corresponding Path message. Furthermore, the egress node SHOULD also ensure that subsequent Resv messages sent by the node contain the same Admin Status Object. Additionally, if an ingress node receives a Resv message with the R bit of the Admin_Status object set, the node SHOULD send an updated Path message containing an Admin_Status object with the same values set, with the exception of the R bit, as received in the corresponding Resv message. Furthermore, the ingress node SHOULD also ensure that subsequent Path messages sent by the node contain the same Admin Status Object. 7.2.1. Deletion procedure In some circumstances, particularly optical networks, it is useful to set the administrative status of an LSP before tearing it down. In such circumstances the procedure SHOULD be followed when deleting an LSP from the ingress: 1. The ingress node precedes an LSP deletion by inserting an Admin Status Object in a Path message and setting the Reflect (R) and Delete (D) bits. 2. Transit and egress nodes process the Admin Status Object as described above. (Alternatively, the egress MAY respond with a PathErr message with the Path_State_Removed flag set, see section 4.4.) Berger Standards Track [Page 19] RFC 3473 GMPLS Signaling - RSVP-TE Extensions January 2003 3. Upon receiving the Admin Status Object with the Delete (D) bit set in the Resv message, the ingress node sends a PathTear message downstream to remove the LSP and normal RSVP processing takes place. In such circumstances the procedure SHOULD be followed when deleting an LSP from the egress: 1. The egress node indicates its desire for deletion by inserting an Admin Status Object in a Resv message and setting the Reflect (R) and Delete (D) bits. 2. Transit nodes process the Admin Status Object as described above. 3. Upon receiving the Admin Status Object with the Delete (D) bit set in the Resv message, the ingress node sends a PathTear message downstream to remove the LSP and normal RSVP processing takes place. 7.2.2. Compatibility and Error Procedures It is possible that some nodes along an LSP will not support the Admin Status Object. In the case of a non-supporting transit node, the object will pass through the node unmodified and normal processing can continue. In the case of a non-supporting egress no