Network Working Group C. Margaria, Ed. Internet-Draft Nokia Siemens Networks Intended status: Standards Track O. Gonzalez de Dios, Ed. Expires: May 2, 2012 Telefonica Investigacion y Desarrollo F. Zhang, Ed. Huawei Technologies October 30, 2011 PCEP extensions for GMPLS draft-ietf-pce-gmpls-pcep-extensions-04 Abstract This memo provides extensions for the Path Computation Element communication Protocol (PCEP) for the support of GMPLS control plane. Status of this Memo This Internet-Draft is submitted in full conformance with the provisions of BCP 78 and BCP 79. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF). Note that other groups may also distribute working documents as Internet-Drafts. The list of current Internet- Drafts is at http://datatracker.ietf.org/drafts/current/. 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." This Internet-Draft will expire on May 2, 2012. Copyright Notice Copyright (c) 2011 IETF Trust and the persons identified as the document authors. All rights reserved. This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents (http://trustee.ietf.org/license-info) in effect on the date of publication of this document. Please review these documents carefully, as they describe your rights and restrictions with respect to this document. Code Components extracted from this document must include Simplified BSD License text as described in Section 4.e of the Trust Legal Provisions and are provided without warranty as Margaria, et al. Expires May 2, 2012 [Page 1] Internet-Draft PCEP Ext for GMPLS October 2011 described in the Simplified BSD License. Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 1.1. Contributing Authors . . . . . . . . . . . . . . . . . . . 3 1.2. PCEP requirements for GMPLS . . . . . . . . . . . . . . . 3 1.3. PCEP existing objects related to GMPLS . . . . . . . . . . 4 1.4. Requirements Language . . . . . . . . . . . . . . . . . . 6 2. PCEP objects and extensions . . . . . . . . . . . . . . . . . 7 2.1. RP object extension . . . . . . . . . . . . . . . . . . . 8 2.2. Traffic parameters encoding, GENERALIZED-BANDWIDTH . . . . 9 2.3. Traffic parameters encoding, GENERALIZED-LOAD-BALANCING . 11 2.4. END-POINTS Object extensions . . . . . . . . . . . . . . . 14 2.4.1. Generalized Endpoint Object Type . . . . . . . . . . . 15 2.4.2. END-POINTS TLVs extensions . . . . . . . . . . . . . . 18 2.5. LABEL-SET object . . . . . . . . . . . . . . . . . . . . . 21 2.6. SUGGESTED-LABEL-SET object . . . . . . . . . . . . . . . . 22 2.7. LSPA extensions . . . . . . . . . . . . . . . . . . . . . 22 2.8. NO-PATH Object Extension . . . . . . . . . . . . . . . . . 23 2.8.1. Extensions to NO-PATH-VECTOR TLV . . . . . . . . . . . 23 3. Additional Error Type and Error Values Defined . . . . . . . . 25 4. Manageability Considerations . . . . . . . . . . . . . . . . . 27 5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 28 5.1. PCEP Objects . . . . . . . . . . . . . . . . . . . . . . . 28 5.2. END-POINTS object, Object Type Generalized Endpoint . . . 29 5.3. New PCEP TLVs . . . . . . . . . . . . . . . . . . . . . . 30 5.4. RP Object Flag Field . . . . . . . . . . . . . . . . . . . 31 5.5. New PCEP Error Codes . . . . . . . . . . . . . . . . . . . 31 5.6. New NO-PATH-VECTOR TLV Fields . . . . . . . . . . . . . . 33 6. Security Considerations . . . . . . . . . . . . . . . . . . . 34 7. Contributing Authors . . . . . . . . . . . . . . . . . . . . . 35 8. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 37 9. References . . . . . . . . . . . . . . . . . . . . . . . . . . 38 9.1. Normative References . . . . . . . . . . . . . . . . . . . 38 9.2. Informative References . . . . . . . . . . . . . . . . . . 39 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 41 Margaria, et al. Expires May 2, 2012 [Page 2] Internet-Draft PCEP Ext for GMPLS October 2011 1. Introduction PCEP RFCs [RFC5440], [RFC5521], [RFC5541], [RFC5520] are focused on path computation requests in MPLS networks. [RFC4655] defines the PCE framework also for GMPLS networks. This document complements these RFCs by providing some consideration of GMPLS applications and routing requests, for example for OTN and WSON networks. The requirements on PCE extensions to support those characteristics are described in [I-D.ietf-pce-gmpls-aps-req] and [I-D.ietf-pce-wson-routing-wavelength]. 1.1. Contributing Authors Elie Sfeir, Franz Rambach (Nokia Siemens Networks) Francisco Javier Jimenez Chico (Telefonica Investigacion y Desarrollo) Suresh BR, Young Lee, SenthilKumar S, Jun Sun (Huawei Technologies), Ramon Casellas (CTTC) 1.2. PCEP requirements for GMPLS This section provides a set of PCEP requirements to support GMPLS LSPs and assure signal compatibility in the path. When requesting a path computation (PCReq) to PCE, the PCC should be able to indicate, according to [I-D.ietf-pce-gmpls-aps-req] and to RSVP procedures like explicit label control (ELC), the following additional attributes: (1) Switching capability: for instance PSC1-4, L2SC, TDM, LSC, FSC (2) Encoding type: as defined in [RFC4202], [RFC4203], e.g., Ethernet, SONET/SDH, Lambda, etc. (3) Signal Type: Indicates the type of elementary signal that constitutes the requested LSP. A lot of signal types with different granularity have been defined in SONET/SDH and G.709 ODUk, such as VC11, VC12, VC2, VC3 and VC4 in SDH, and ODU1, ODU2 and ODU3 in G.709 ODUk [RFC4606], [RFC4328] and other signal types like the one defined in [I-D.ceccarelli-ccamp-gmpls-ospf-g709] or [I-D.zhang-ccamp-gmpls-evolving-g709] . (4) Concatenation Type: In SDH/SONET and G.709 OTN networks, two kinds of concatenation modes are defined: contiguous concatenation which requires co-route for each member signal and requires all the interfaces along the path to support this capability, and virtual concatenation which allows diverse routes for the member signals and only requires the ingress and egress interfaces to support this capability. Note that for the virtual concatenation, it also may specify co-routed or separated-routed. See [RFC4606] Margaria, et al. Expires May 2, 2012 [Page 3] Internet-Draft PCEP Ext for GMPLS October 2011 and [RFC4328] about concatenation information. (5) Concatenation Number: Indicates the number of signals that are requested to be contiguously or virtually concatenated. See also [RFC4606] and [RFC4328]. (6) Technology specific label(s) such as wavelength label as defined in [RFC6205] (7) e2e Path protection type: as defined in [RFC4872], e.g., 1+1 protection, 1:1 protection, (pre-planned) rerouting, etc. (8) Link Protection type: as defined in [RFC4203] (9) Support for unnumbered interfaces: as defined in [RFC3477] (10) Support for asymmetric bandwidth requests. (11) Ability to indicate the requested granularity for the path ERO: node, link, label. This is to allow the use of the explicit label control of RSVP. (12) In order to support the label control the Path computation response should provide label information matching signaling capabilities (13) The PCC should be able to provide label restrictions similar to RSVP on the requests. We describe in this document a proposal to fulfill those requirements. 1.3. PCEP existing objects related to GMPLS PCEP as of [RFC5440], [RFC5521] and [I-D.ietf-pce-inter-layer-ext], supports the following information (in the PCReq and PCRep) related to the described requirements. From [RFC5440]: o numbered endpoints o bandwidth (encoded as IEEE float) o ERO o LSP attributes (setup and holding priorities) Margaria, et al. Expires May 2, 2012 [Page 4] Internet-Draft PCEP Ext for GMPLS October 2011 o Request attribute (include some LSP attributes) From [RFC5521],Extensions to PCEP for Route Exclusions, definition of a XRO object and a new semantic (F bit): o This object also allows to exclude (strict or not) resources; XRO include the diversity level (node, link, SRLG). The requested diversity is expressed in the XRO o This Object with the F bit set indicates that the existing route is failed and resources present in the RRO can be reused. From [I-D.ietf-pce-inter-layer-ext]: o INTER-LAYER : indicates if inter-layer computation is allowed o SWITCH-LAYER : indicates which layer(s) should be considered, can be used to represent the RSVP-TE generalized label request o REQ-ADAP-CAP : indicates the adaptation capabilities requested, can also be used for the endpoints in case of mono-layer computation The shortcomings of the existing PCEP information are: The BANDWIDTH and LOAD-BALANCING objects do not describe the details of the traffic request (for example NVC, multiplier) in the context of GMPLS networks, for instance TDM or OTN networks. The END-POINTS object does not allow specifying an unnumbered interface, nor the labels on the interface. Those parameters are of interest in case of switching constraints. Current attributes do not allow to express the requested link level protection and end-to-end protection attributes. The covered PCEP extensions are: New objects are introduced (GENERALIZED-BANDWIDTH and GENERALIZED- LOAD-BALANCING) for flexible bandwidth encoding, New Objects are introduced (LABEL-SET and SUGGESTED-LABEL-SET) on order to allow the PCC to restrict/influence the range of labels returned A new object type is introduced for the END-POINTS object (generalized-endpoint), Margaria, et al. Expires May 2, 2012 [Page 5] Internet-Draft PCEP Ext for GMPLS October 2011 A new TLV is added to the LSPA object. In order to indicate the mandatory routing granularity in the response, a new flag in the RP object is added. 1.4. Requirements Language The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in [RFC2119]. Margaria, et al. Expires May 2, 2012 [Page 6] Internet-Draft PCEP Ext for GMPLS October 2011 2. PCEP objects and extensions This section describes the required PCEP objects and extensions. The PCReq and PCRep messages are defined in [RFC5440]. The format of the request and response messages with the proposed extensions (GENERALIZED-BANDWIDTH, GENERALIZED-LOAD-BALANCING, SUGGESTED-LABEL- SET and LABEL-SET) is as follows: ::= | ::= [] [] [...] [] [] [ [] [...]] [] [] [...] [] [...] [] ::= ::= [] [] [] ::=[] ::= ::=[] Where: ::=[] [] [...] [...] [...] [...] [] [] Margaria, et al. Expires May 2, 2012 [Page 7] Internet-Draft PCEP Ext for GMPLS October 2011 For point-to-multipoint(P2MP) computations, the proposed grammar is: ::= [] [] [...] [] [] [] [] [] [...] [] ::= [][] [...] [] ::=[] [< GENERALIZED-BANDWIDTH>...][] 2.1. RP object extension Explicit label control (ELC) is a procedure supported by RSVP-TE, where the outgoing label(s) is(are) encoded in the ERO. In consequence, the PCE may be able to provide such label(s) directly in the path ERO. The PCC, depending on policies or switching layer, may be required to use explicit label control or expect explicit link, thus it need to indicate in the PCReq which granularity it is expecting in the ERO. This correspond to requirement 11 of [I-D.ietf-pce-gmpls-aps-req] The possible granularities can be node, link, label. The granularities are inter-dependent, in the sense that link granularity imply the presence of node information in the ERO, similarly a label granularity imply that the ERO contain node, link and label information. A new 2-bit routing granularity (RG) flag is defined in the RP object. The values are defined as follows Margaria, et al. Expires May 2, 2012 [Page 8] Internet-Draft PCEP Ext for GMPLS October 2011 0 : node 1 : link 2 : label 3 : reserved When the RP object appears in a request within a PCReq message the flag indicates the requested route granularity. The PCE MAY try to follow this granularity and MAY return a NO-PATH if the requested granularity cannot be provided. The PCE MAY return more details on the route based on its policy. The PCC can decide if the ERO is acceptable based on its content. If a PCE did use the requested routing granularity in a PCReq is MUST indicate the routing granularity in the PCRep. The RG flag is backward-compatible with previous RFCs: the value sent by an implementation not supporting it will indicate a node granularity. This flag is optional for responses. A new capability flag in the PCE-CAP-FLAGS from [RFC5088] and [RFC5089] may be added. 2.2. Traffic parameters encoding, GENERALIZED-BANDWIDTH The PCEP BANDWIDTH does not describe the details of the signal (for example NVC, multiplier), hence the bandwidth information should be extended to use the RSVP Tspec object encoding. The PCEP BANDWIDTH object defines two types: 1 and 2. C-Type 2 is representing the existing bandwidth in case of re-optimization. The following possibilities cannot be represented in the BANDWIDTH object: o Asymmetric bandwidth (different bandwidth in forward and reverse direction), as described in [RFC6387] o GMPLS (SDH/SONET, G.709, ATM, MEF etc) parameters are not supported. This correspond to requirement 3,4,5 and 10 of [I-D.ietf-pce-gmpls-aps-req]. According to [RFC5440] the BANDWIDTH object has no TLV and has a fixed size of 4 bytes. This definition does not allow extending it with the required information. To express this information, a new object named GENERALIZED-BANDWIDTH having the following format is defined: Margaria, et al. Expires May 2, 2012 [Page 9] Internet-Draft PCEP Ext for GMPLS October 2011 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Traffic Spec Length | Reserved |R|O| +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | | ~ Traffic Spec ~ | | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | | ~ Optional TLVs ~ | | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ The GENERALIZED-BANDWIDTH has a variable length. The Traffic spec length field indicates the length of the Traffic spec field. The bits R and O have the following meaning: O bit : when set the value refers to the previous bandwidth in case of re-optimization R bit : when set the value refers to the bandwidth of the reverse direction The Object type determines which type of bandwidth is represented by the object. The following object types are defined: 1. Intserv 2. SONET/SDH 3. G.709 4. Ethernet The encoding of the field Traffic Spec is the same as in RSVP-TE, it can be found in the following references. Margaria, et al. Expires May 2, 2012 [Page 10] Internet-Draft PCEP Ext for GMPLS October 2011 Object Type Name Reference 0 Reserved 1 Reserved 2 Intserv [RFC2210] 3 Reserved 4 SONET/SDH [RFC4606] 5 G.709 [RFC4328] 6 Ethernet [RFC6003] Traffic Spec field encoding The GENERALIZED-BANDWIDTH MAY appear more than once in a PCReq message. If more than one GENERALIZED-BANDWIDTH have the same Object Type, Reserved, R and O values, only the first one is processed, the others are ignored. a PCE MAY ignore GENERALIZED-BANDWIDTH objects, a PCC that requires a GENERALIZED-BANDWIDTH to be used can set the P (Processing) bit in the object header. When a PCC needs to get a bi-directional path with asymmetric bandwidth, it SHOULD specify the different bandwidth in forward and reverse directions through two separate GENERALIZED-BANDWIDTH objects. If the PCC set the P bit on both object the PCE MUST compute a path that satisfies the asymmetric bandwidth constraint and return the path to PCC if the path computation is successful. If the P bit on the reverse GENERALIZED-BANDWIDTH object the PCE MAY ignore this constraint. a PCE MAY include the GENERALIZED-BANDWIDTH objects in the response to indicate the GENERALIZED-BANDWIDTH of the path Optional TLVs may be included within the object body to specify more specific bandwidth requirements. The specification of such TLVs is outside the scope of this document. 2.3. Traffic parameters encoding, GENERALIZED-LOAD-BALANCING The LOAD-BALANCING object is used to request a set of maximum Max-LSP TE-LSP having in total the bandwidth specified in BANDWIDTH, each TE- LSP having a minimum of min-bandwidth bandwidth. The LOAD-BALANCING Margaria, et al. Expires May 2, 2012 [Page 11] Internet-Draft PCEP Ext for GMPLS October 2011 follows the bandwidth encoding of the BANDWIDTH object, it does not describe enough details for the traffic specification expected by GMPLS. A PCC should be allowed to request a set of TE-LSP also in case of GMPLS traffic specification. According to [RFC5440] the LOAD-BALANCING object has no TLV and has a fixed size of 8 bytes. This definition does not allows extending it with the required information. To express this information, a new Object named GENERALIZED-LOAD-BALANCING is defined. The GENERALIZED-LOAD-BALANCING object, as the LOAD-BALANCING object, allows the PCC to request a set of TE-LSP having in total the GENERALIZED-BANDWIDTH traffic specification with potentially Max-Lsp, each TE-LSP having a minimum of Min Traffic spec. The GENERALIZED- LOAD-BALANCING is optional. GENERALIZED-LOAD-BALANCING Object-Class is to be assigned by IANA. The GENERALIZED-LOAD-BALANCING Object type determines which type of minimum bandwidth is represented by the object. The following object types are defined: 1. Intserv 2. SONET/SDH 3. G.709 4. Ethernet The GENERALIZED-LOAD-BALANCING has a variable length. The format of the GENERALIZED-LOAD-BALANCING object body 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Traffic spec length | Flags |R| Max-LSP | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Min Traffic Spec | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | | ~ Optional TLVs ~ | | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Traffic spec length (16 bits): the total length of the min traffic specification. It should be noted that the RSVP traffic Margaria, et al. Expires May 2, 2012 [Page 12] Internet-Draft PCEP Ext for GMPLS October 2011 specification may also include TLV different than the PCEP TLVs. Flags (8 bits): The undefined Flags field MUST be set to zero on transmission and MUST be ignored on receipt. The following flag is defined: R Flag : (1 bit) set when the value refer to the bandwidth of the reverse direction Max-LSP (8 bits): maximum number of TE LSPs in the set. Min-Traffic spec (variable): Specifies the minimum traffic spec of each element of the set of TE LSPs. The encoding of the field Traffic Spec is the same as in RSVP-TE, it can be found in the following references. Object Type Name Reference 2 Intserv [RFC2210] 4 SONET/SDH [RFC4606] 5 G.709 [RFC4328] 6 Ethernet [RFC6003] Traffic Spec field encoding The GENERALIZED-LOAD-BALANCING MAY appear more than once in a PCReq message. If more than one GENERALIZED-LOAD-BALANCING have the same Object Type, and R Flag, only the first one is processed, the others are ignored. a PCE MAY ignore GENERALIZED-LOAD-BALANCING objects. A PCC that requires a GENERALIZED-LOAD-BALANCING to be used can set the P (Processing) bit in the object header. When a PCC needs to get a bi-directional path with asymmetric bandwidth, it SHOULD specify the different bandwidth in forward and reverse directions through two separate GENERALIZED-LOAD-BALANCING objects with different R Flag. If the PCC set the P bit on both object the PCE MUST compute a path that satisfies the asymmetric bandwidth constraint and return the path to PCC if the path computation is successful. If the P bit on the reverse GENERALIZED- LOAD-BALANCING object the PCE MAY ignore this constraint. Optional TLVs may be included within the object body to specify more Margaria, et al. Expires May 2, 2012 [Page 13] Internet-Draft PCEP Ext for GMPLS October 2011 specific bandwidth requirements. The specification of such TLVs is outside the scope of this document. The GENERALIZED-LOAD-BALANCING object has the same semantic as the LOAD-BALANCING object; If a PCC requests the computation of a set of TE LSPs so that the total of their generalized bandwidth is X, the maximum number of TE LSPs is N, and each TE LSP must at least have a bandwidth of B, it inserts a GENERALIZED-BANDWIDTH object specifying X as the required bandwidth and a GENERALIZED-LOAD-BALANCING object with the Max-LSP and Min-traffic spec fields set to N and B, respectively. For example a request for one co-signaled n x VC-4 TE-LSP will not use the GENERALIZED-LOAD-BALANCING. In case the V4 components can use different paths, the GENERALIZED-BANDWIDTH will contain a traffic specification indicating the complete n x VC4 traffic specification and the GENERALIZED-LOAD-BALANCING the minimum co-signaled VC4. For a SDH network, a request to have a TE-LSP group with 10 VC4 container, each path using at minimum 2VC4 container, can be represented with a GENERALIZED-BANDWIDTH object with OT=4, the content of the Traffic specification is ST=6,RCC=0,NCC=0,NVC=10,MT=1. The GENERALIZED-LOAD-BALANCING, OT=4,R=0,Max-LSP=5, min Traffic spec is (ST=6,RCC=0,NCC=0,NVC=2,MT=1). The PCE can respond with a response with maximum 5 path, each of then having a GENERALIZED- BANDWIDTH OT=4,R=0, and traffic spec matching the minimum traffic spec from the GENERALIZED-LOAD-BALANCING object of the corresponding request. 2.4. END-POINTS Object extensions The END-POINTS object is used in a PCReq message to specify the source and destination of the path for which a path computation is requested. From [RFC3471] the source IP address and the destination IP address are used to identify those. A new Object Type is defined to address the following possibilities: o Different endpoint types. o Label restrictions on the endpoint. o Specification of unnumbered endpoints type as seen in GMPLS networks. The Object encoding is described in the following sections. Margaria, et al. Expires May 2, 2012 [Page 14] Internet-Draft PCEP Ext for GMPLS October 2011 2.4.1. Generalized Endpoint Object Type In GMPLS context the endpoints can: o Be unnumbered o Have label(s) associated to them o May have different switching capabilities The IPv4 and IPv6 endpoints are used to represent the source and destination IP addresses. The scope of the IP address (Node or Link) is not explicitly stated. It should also be possible to request a Path between a numbered link and an unnumbered link, or a P2MP path between different type of endpoints. Since the PCEP END-POINTS object only support endpoints of the same type a new C-Type is proposed that support different endpoint types, including unnumbered. This new C-Type also supports the specification of constraints on the endpoint label to be use. The PCE might know the interface restrictions but this is not a requirement. On the path calculation request only the Tspec and switch layer need to be coherent, the endpoint labels could be different (supporting a different Tspec). Hence the label restrictions include a Generalized label request in order to interpret the labels. This correspond to requirement 6 and 9 of [I-D.ietf-pce-gmpls-aps-req]. The proposed object format consists of a body and a list of TLVs, which give the details of the endpoints and are described in Section 2.4.2. For each endpoint type, a different grammar is defined. The TLVs defined to describe an endpoint are: 1. IPv4 address. 2. IPv6 address. 3. Unnumbered endpoint. 4. Label request. 5. Label. 6. Upstream label. 7. Label set. Margaria, et al. Expires May 2, 2012 [Page 15] Internet-Draft PCEP Ext for GMPLS October 2011 8. Suggested label set. The labels TLV are used to restrict the label allocation in the PCE. They follow the set of restrictions provided by signaling with explicit value (label and upstream label), mandatory range restrictions (Label set) and optional range restriction (suggested label set). Single suggested value is using the suggested label set. The label range restriction are valid in GMPLS networks, either by PCC policy or depending on the switching technology used, for instance on given Ethernet or ODU equipment having limited hardware capabilities restricting the label range. Label set restriction also applies to WSON networks where the optical sender and receivers are limited in their frequency tunability ranges, restricting then in GMPLS the possible label ranges on the interface. The END-POINTS Object with Generalized Endpoint object type is encoded as follow: 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Reserved | endpoint type | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | | ~ TLVs ~ | | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Reserved bits should be set to 0 when a message is sent and ignored when the message is received the endpoint type is defined as follow: Margaria, et al. Expires May 2, 2012 [Page 16] Internet-Draft PCEP Ext for GMPLS October 2011 Value Type Meaning 0 Point-to-Point 1 Point-to-Multipoint New leaves to add 2 Old leaves to remove 3 Old leaves whose path can be modified/reoptimized 4 Old leaves whose path must be left unchanged 5-244 Reserved 245-255 Experimental range The endpoint type is used to cover both point-to-point and different point-to-multipoint endpoint semantic. Endpoint type 0 MAY be accepted by the PCE, other endpoint type MAY be supported if the PCE implementation supports P2MP path calculation. A PCE not supporting a given endpoint type MUST respond with a PCErr with error code "Path computation failure", error type "Unsupported endpoint type in END- POINTS Generalized Endpoint object type". The TLVs present in the object body MUST follow the following grammar: ::= | ::= ::= [] ::= [] ::= [] [ []]... For endpoint type Point-to-Multipoint several endpoint objects may be Margaria, et al. Expires May 2, 2012 [Page 17] Internet-Draft PCEP Ext for GMPLS October 2011 present in the message and represent a leave, exact meaning depend on the endpoint type defined of the object. An endpoint is defined as follows: ::=|| ::= [] ::= ::= [] ::=