PCEP Extension for WSON Routing and Wavelength Assignment
Author(s): Ramon Casellas, Young Lee
This document provides the Path Computation Element communication Protocol (PCEP) extensions for the support of Routing and Wavelength Assignment (RWA) in Wavelength Switched Optical Networks (WSON). Lightpath provisioning in WSONs requires a routing and wavelength assignment (RWA) process....
Network Working Group Y. Lee, Ed. Internet Draft Huawei Technologies Intended status: Standard R. Casellas, Ed. Expires: January 2014 CTTC July 12, 2013 PCEP Extension for WSON Routing and Wavelength Assignment draft-ietf-pce-wson-rwa-ext-01.txt Abstract This document provides the Path Computation Element communication Protocol (PCEP) extensions for the support of Routing and Wavelength Assignment (RWA) in Wavelength Switched Optical Networks (WSON). Lightpath provisioning in WSONs requires a routing and wavelength assignment (RWA) process. From a path computation perspective, wavelength assignment is the process of determining which wavelength can be used on each hop of a path and forms an additional routing constraint to optical light path computation. Status of this Memo This Internet-Draft is submitted to IETF in full conformance with the provisions of BCP 78 and BCP 79. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF), its areas, and its working groups. Note that other groups may also distribute working documents as Internet- Drafts. Internet-Drafts 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 Lee & Casellas Expires January 12, 2014 [Page 1] Internet-Draft PCEP Extension for WSON RWA July 2013 The list of Internet-Draft Shadow Directories can be accessed at http://www.ietf.org/shadow.html. This Internet-Draft will expire on January 12, 2009. Copyright Notice Copyright (c) 2013 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 described in the Simplified BSD License. Table of Contents 1. Terminology....................................................3 2. Requirements Language..........................................3 3. Introduction...................................................3 4. Encoding of a RWA Path Request.................................6 4.1. Wavelength Assignment (WA) Object.........................6 4.2. Wavelength Restriction Constraint TLV.....................8 4.2.1. Link Identifier Entry...............................10 4.2.2. Wavelength Restriction Field........................12 4.3. Signal processing capability restrictions................12 4.3.1. Signal Processing Exclusion XRO Sub-Object..........13 4.3.2. IRO sub-object: signal processing inclusion.........14 5. Encoding of a RWA Path Reply..................................14 5.1. Error Indicator..........................................14 5.2. NO-PATH Indicator........................................15 6. Manageability Considerations..................................15 6.1. Control of Function and Policy...........................15 6.2. Information and Data Models, e.g. MIB module.............16 6.3. Liveness Detection and Monitoring........................16 6.4. Verifying Correct Operation..............................16 6.5. Requirements on Other Protocols and Functional Components16 6.6. Impact on Network Operation..............................17 7. Security Considerations.......................................17 Lee & Casellas Expires January12,2014 [Page 2] Internet-Draft PCEP Extension for WSON RWA July 2013 8. IANA Considerations...........................................17 9. Acknowledgments...............................................17 10. References...................................................17 10.1. Informative References..................................17 11. Contributors.................................................19 Authors' Addresses...............................................20 Intellectual Property Statement..................................20 Disclaimer of Validity...........................................21 1. Terminology This document uses the terminology defined in [RFC4655], and [RFC5440]. 2. 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 [RFC 2119]. 3. Introduction [RFC4655] defines a PCE based path computation architecture and explains how a Path Computation Element (PCE) may compute Label Switched Paths (LSP) in Multiprotocol Label Switching Traffic Engineering (MPLS-TE) and Generalized MPLS (GMPLS) networks at the request of Path Computation Clients (PCCs). A PCC is said to be any network component that makes such a request and may be, for instance, an Optical Switching Element within a Wavelength Division Multiplexing (WDM) network. The PCE, itself, can be located anywhere within the network, and may be within an optical switching element, a Network Management System (NMS) or Operational Support System (OSS), or may be an independent network server. The PCE communications Protocol (PCEP) is the communication protocol used between a PCC and a PCE, and may also be used between cooperating PCEs. [RFC4657] sets out the common protocol requirements for PCEP. Additional application-specific requirements for PCEP are deferred to separate documents. This document provides the PCEP extensions for the support of Routing and Wavelength Assignment (RWA) in Wavelength Switched Lee & Casellas Expires January12,2014 [Page 3] Internet-Draft PCEP Extension for WSON RWA July 2013 Optical Networks (WSON) based on the requirements specified in [PCE- RWA]. WSON refers to WDM based optical networks in which switching is performed selectively based on the wavelength of an optical signal. In this document, it is assumed that wavelength converters require electrical signal regeneration. Consequently, WSONs can be transparent (A transparent optical network is made up of optical devices that can switch but not convert from one wavelength to another, all within the optical domain) or translucent (3R regenerators are sparsely placed in the network). A LSC Label Switched Path (LSP) may span one or several transparent segments, which are delimited by 3R regenerators (typically with electronic regenerator and optional wavelength conversion). Each transparent segment or path in WSON is referred to as an optical path. An optical path may span multiple fiber links and the path should be assigned the same wavelength for each link. In such case, the optical path is said to satisfy the wavelength-continuity constraint. Figure 1 illustrates the relationship between a LSC LSP and transparent segments (optical paths). +---+ +-----+ +-----+ +-----+ +-----+ | |I1 | | | | | | I2| | | |o------| |-------[(3R) ]------| |--------o| | | | | | | | | | | | +---+ +-----+ +-----+ +-----+ +-----+ [X LSC] [LSC LSC] [LSC LSC] [LSC X] SwCap <-------> <-------> <-----> <-------> <-----------------------><----------------------> Transparent Segment Transparent Segment <-------------------------------------------------> LSC LSP Figure 1 Illustration of a LSC LSP and transparent segments Note that two optical paths within a WSON LSP need not operate on the same wavelength (due to the wavelength conversion capabilities). Two optical paths that share a common fiber link cannot be assigned the same wavelength. To do otherwise would result in both signals interfering with each other. Note that advanced additional multiplexing techniques such as polarization based multiplexing are not addressed in this document since the physical layer aspects are not currently standardized. Therefore, assigning the proper Lee & Casellas Expires January12,2014 [Page 4] Internet-Draft PCEP Extension for WSON RWA July 2013 wavelength on a lightpath is an essential requirement in the optical path computation process. When a switching node has the ability to perform wavelength conversion, the wavelength-continuity constraint can be relaxed, and a LSC Label Switched Path (LSP) may use different wavelengths on different links along its route from origin to destination. It is, however, to be noted that wavelength converters may be limited due to their relatively high cost, while the number of WDM channels that can be supported in a fiber is also limited. As a WSON can be composed of network nodes that cannot perform wavelength conversion, nodes with limited wavelength conversion, and nodes with full wavelength conversion abilities, wavelength assignment is an additional routing constraint to be considered in all lightpath computation. For example (see Figure 1), within a translucent WSON, a LSC LSP may be established between interfaces I1 and I2, spanning 2 transparent segments (optical paths) where the wavelength continuity constraint applies (i.e. the same unique wavelength MUST be assigned to the LSP at each TE link of the segment). If the LSC LSP induced a Forwarding Adjacency / TE link, the switching capabilities of the TE link would be [X X] where X < LSC (PSC, TDM, ...). This document aligns with GMPLS extensions for PCEP [PCEP-GMPLS] for generic property such as label, label-set and label assignment noting that wavelength is a type of label. Wavelength restrictions and constraints are also formulated in terms of labels per [GEN- ENCODE]. The optical modulation properties, which are also referred to as signal compatibility, are already considered in signaling in [RWA- Encode] and [WSON-OSPF]. In order to improve the signal quality and limit some optical effects several advanced modulation processing are used. Those modulation properties contribute not only to optical signal quality checks but also constrain the selection of sender and receiver, as they should have matching signal processing capabilities. This document includes signal compatibility constraints as part of RWA path computation. That is, the signal processing capabilities (e.g., modulation and FEC) must be compatible between the sender and the receiver of the optical path across all optical elements. This document, however, does not address optical impairments as part of RWA path computation. See [WSON-Imp] and [RSVP-Imp] for more information on optical impairments and GMPLS. Lee & Casellas Expires January12,2014 [Page 5] Internet-Draft PCEP Extension for WSON RWA July 2013 4. Encoding of a RWA Path Request Figure 2 shows one typical PCE based implementation, which is referred to as the Combined Process (R&WA). With this architecture, the two processes of routing and wavelength assignment are accessed via a single PCE. This architecture is the base architecture from which the requirements have been specified in [PCE-RWA] and the PCEP extensions that are going to be specified in this document based on this architecture. +----------------------------+ +-----+ | +-------+ +--+ | | | | |Routing| |WA| | | PCC |<----->| +-------+ +--+ | | | | | +-----+ | PCE | +----------------------------+ Figure 2 Combined Process (R&WA) architecture 4.1. Wavelength Assignment (WA) Object Wavelength allocation can be performed by the PCE by different means: (a) By means of Explicit Label Control, in the sense that one (or two) allocated labels MAY appear after an interface route subobject. (b) By means of a Label Set, containing one or more allocated Labels, provided by the PCE. Option (b) allows distributed label allocation (performed during signaling) to complete wavelength assignment. Additionally, given a range of potential labels to allocate, the request SHOULD convey the heuristic / mechanism to the allocation. The format of a PCReq message after incorporating the WA object is as follows: <PCReq Message> ::= <Common Header> [<svec-list>] <request-list> Where: Lee & Casellas Expires January12,2014 [Page 6] Internet-Draft PCEP Extension for WSON RWA July 2013 <request-list>::=<request>[<request-list>] <request>::= <RP> <ENDPOINTS> <WA> [other optional objects...] If the WA object is present in the request, it MUST be encoded after the ENDPOINTS object. The format of the Wavelength Assignment (WA) 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Flags | O |M| +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Wavelength Restriction TLV | . . . . +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ // Optional TLVs // | | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Figure 3 WA Object o Flags (32 bits) The following new flags SHOULD be set . M (Mode - 1 bit): M bit is used to indicate the mode of wavelength assignment. When M bit is set to 1, this indicates that the label assigned by the PCE must be explicit. That is, the selected way to convey the allocated wavelength is by means of Explicit Label Control (ELC) [RFC4003] for each hop of a computed LSP. Otherwise, the label assigned by the PCE needs not be explicit (i.e., it can be suggested in the form of label set objects in the corresponding response, to allow distributed WA. In such case, the PCE MUST return a Label Set object as described in Section 2.2 of [Gen-Encode] in the response. Lee & Casellas Expires January12,2014 [Page 7] Internet-Draft PCEP Extension for WSON RWA July 2013 . O (Order - 3 bits): O bit is used to indicate the wavelength assignment constraint in regard to the order of wavelength assignment to be returned by the PCE. This case is only applied when M bit is set to "explicit." The following indicators should be defined: 000 - Reserved 001 - Random Assignment 010 - First Fit (FF) in descending Order 011 - First Fit (FF) in ascending Order 100 - Last Fit (LF) in ascending Order 101 - Last Fit (LF) in descending Order 110 - Unspecified 111 - Reserved 4.2. Wavelength Restriction Constraint TLV For any request that contains a wavelength assignment, the requester (PCC) MUST be able to specify a restriction on the wavelengths to be used. This restriction is to be interpreted by the PCE as a constraint on the tuning ability of the origination laser transmitter or on any other maintenance related constraints. Note that if the LSP LSC spans different segments, the PCE MUST have mechanisms to know the tunability restrictions of the involved wavelength converters / regenerators, e.g. by means of the TED either via IGP or NMS. Even if the PCE knows the tunability of the transmitter, the PCC MUST be able to apply additional constraints to the request. The TLV type is TBD, recommended value is TBD. This TLV MAY appear more than once to be able to specify multiple restrictions. The TLV data is defined as follows: <Wavelength Restriction Constraint> ::= <Action> <Count> <Reserved> Lee & Casellas Expires January12,2014 [Page 8] Internet-Draft PCEP Extension for WSON RWA July 2013 (<Link Identifiers> <Wavelength Restriction>)... Where <Link Identifiers> ::= <Link Identifier> [<Link Identifiers>] <Link Identifier> ::= <Unnumbered IF ID> | <IPV4 Address> | <IPV6 Address> 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Action | Count | Reserved | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Link Identifiers | | . . . | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Wavelength Restriction Field | // . . . . // +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Figure 4 Wavelength Restriction o Action: 8 bits . 0 - Inclusive List indicates that one or more link identifiers are included in the Link Set. Each identifies a separate link that is part of the set. Lee & Casellas Expires January12,2014 [Page 9] Internet-Draft PCEP Extension for WSON RWA July 2013 . 1 - Inclusive Range indicates that the Link Set defines a range of links. It contains two link identifiers. The first identifier indicates the start of the range (inclusive). The second identifier indicates the end of the range (inclusive). All links with numeric values between the bounds are considered to be part of the set. A value of zero in either position indicates that there is no bound on the corresponding portion of the range. Note that the Action field can be set to 0 when unnumbered link identifier is used. Note that "interfaces" such as those discussed in the Interfaces MIB [RFC2863] are assumed to be bidirectional. o Count: The number of of the link identifiers (8 bits) Note that a PCC MAY add a Wavelength restriction that applies to all links by setting the Count field to zero and specifying just a set of wavelengths. Note that all link identifiers in the same list must be of the same type. o Reserved: Reserved for future use (16 bits) o Link Identifiers: Identifies each link ID for which restriction is applied. The length is dependent on the link format and the Count field. See the following section for Link Identifier encoding. 4.2.1. Link Identifier Entry The link identifier field can be an IPv4, IPv6 or unnumbered interface ID. <Link Identifier> ::= <IPV4 Address> | <IPV6 Address> | <Unnumbered IF ID> The encoding of each case is as follows: Lee & Casellas Expires January12,2014 [Page 10] Internet-Draft PCEP Extension for WSON RWA July 2013 IPv4 prefix Entry 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 = 1 | IPv4 address (4 bytes) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | IPv4 address (continued) | Prefix Length | Attribute | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ IPv6 prefix Sub-TLV 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 = 2 | IPv6 address (16 bytes) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | IPv6 address (continued) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | IPv6 address (continued) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | IPv6 address (continued) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | IPv6 address (continued) | Prefix Length | Attribute | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Unnumbered Interface ID Sub-TLV 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 = 4 | Reserved | Attribute | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | TE Node ID | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Interface ID | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+- Lee & Casellas Expires January12,2014 [Page 11] Internet-Draft PCEP Extension for WSON RWA July 2013 4.2.2. Wavelength Restriction Field The Wavelength Restriction Field of the wavelength restriction TLV is encoded as a Label Set field as specified in [GEN-Encode] section 2.2, as shown below, with base label encoded as a 32 bit LSC label, defined in [RFC6205]. See [RFC6205] for a description of Grid, C.S, Identifier and n, as well as [GEN-Encode] for the details of each action. 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Action| Num Labels | Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |Grid | C.S | Identifier | n | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Additional fields as necessary per action | | | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 4.3. Signal processing capability restrictions Path computation for WSON include the check of signal processing capabilities, those capability MAY be provided by the IGP, however this is not a MUST. Moreover, a PCC should be able to indicate additional restrictions for those signal compatibility, either on the endpoint or any given link. The supported signal processing capabilities are the one described in [RWA-Info]: . Optical Interface Class List . Bit rate . Client signal The Bit-rate restriction is already expressed in [PCEP-GMPLS] in the GENERALIZED-BANDWIDTH object. The client signal information can be expressed using the REQ-ADAP- CAP object from the [PCEP-Layer]. Lee & Casellas Expires January12,2014 [Page 12] Internet-Draft PCEP Extension for WSON RWA July 2013 In order to support the Optical Interface Class information a new TLV is introduced as endpoint-restriction in the END-POINTS type Generalized endpoint: . Optical Interface Class List TLV The END-POINTS type generalized endpoint is extended as follows: <endpoint-restrictions> ::= <LABEL-REQUEST> <Wavelength Restriction Constraint> [<signal-compatibility-restriction>...] Where signal-compatibility-restriction ::= <Optical Interface Class List> The encoding for Optical Interface Class List is described in Section 5.2 of [RWA-Encode]. 4.3.1. Signal Processing Exclusion XRO Sub-Object The PCC/PCE should be able to exclude particular types of signal processing along the path in order to handle client restriction or multi-domain path computation. In order to support the exclusion a new XRO sub-object is defined: the signal processing exclusion: 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |X| Type = X | Length | Reserved | Attribute | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | sub-sub objects | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Lee & Casellas Expires January12,2014 [Page 13] Internet-Draft PCEP Extension for WSON RWA July 2013 Figure 5 Signaling Processing XRO Sub-Object The Attribute field indicates how the exclusion sub-object is to be interpreted. The Attribute can only be 0 (Interface) or 1 (Node). The sub-sub objects are encoded as in RSVP signaling definition [WSON-Sign]. 4.3.2. IRO sub-object: signal processing inclusion Similar to the XRO sub-object the PCC/PCE should be able to include particular types of signal processing along the path in order to handle client restriction or multi-domain path computation. This is supported by adding the sub-object "processing" defined for ERO in [WSON-Sign] to the PCEP IRO object. 5. Encoding of a RWA Path Reply The ERO is used to encode the path of a TE LSP through the network. The ERO is carried within a given path of a PCEP response, which is in turn carried in a PCRep message to provide the computed TE LSP if the path computation was successful. The preferred way to convey the allocated wavelength is by means of Explicit Label Control (ELC) [RFC4003]. In order to encode wavelength assignment, the Wavelength Assignment (WA) Object needs to be employed to be able to specify wavelength assignment. Since each segment of the computed optical path is associated with wavelength assignment, the WA Object should be aligned with the ERO object. Encoding details will be provided further revisions and will be aligned as much as possible with [WSON-Sign] and [LSPA-ERO] 5.1. Error Indicator To indicate errors associated with the RWA request, a new Error Type (TDB) and subsequent error-values are defined as follows for inclusion in the PCEP-ERROR Object: A new Error-Type (TDB) and subsequent error-values are defined as follows: Lee & Casellas Expires January12,2014 [Page 14] Internet-Draft PCEP Extension for WSON RWA July 2013 . Error-Type=TBD; Error-value=1: if a PCE receives a RWA request and the PCE is not capable of processing the request due to insufficient memory, the PCE MUST send a PCErr message with a PCEP-ERROR Object (Error-Type=TDB) and an Error-value(Error- value=1). The PCE stops processing the request. The corresponding RWA request MUST be cancelled at the PCC. . Error-Type=TBD; Error-value=2: if a PCE receives a RWA request and the PCE is not capable of RWA computation, the PCE MUST send a PCErr message with a PCEP-ERROR Object (Error-Type=TDB) and an Error-value (Error-value=2). The PCE stops processing the request. The corresponding RWA computation MUST be cancelled at the PCC. 5.2. NO-PATH Indicator To communicate the reason(s) for not being able to find RWA for the path request, the NO-PATH object can be used in the corresponding response. The format of the NO-PATH object body is defined in [RFC5440]. The object may contain a NO-PATH-VECTOR TLV to provide additional information about why a path computation has failed. One new bit flag are defined to be carried in the Flags field in the NO-PATH-VECTOR TLV carried in the NO-PATH Object. . Bit TDB: When set, the PCE indicates no feasible route was found that meets all the constraints (e.g., wavelength restriction, signal compatibility, etc.) associated with RWA. 6. Manageability Considerations Manageability of WSON Routing and Wavelength Assignment (RWA) with PCE must address the following considerations: 6.1. Control of Function and Policy In addition to the parameters already listed in Section 8.1 of [PCEP], a PCEP implementation SHOULD allow configuring the following PCEP session parameters on a PCC: Lee & Casellas Expires January12,2014 [Page 15] Internet-Draft PCEP Extension for WSON RWA July 2013 . The ability to send a WSON RWA request. In addition to the parameters already listed in Section 8.1 of [PCEP], a PCEP implementation SHOULD allow configuring the following PCEP session parameters on a PCE: . The support for WSON RWA. . A set of WSON RWA specific policies (authorized sender, request rate limiter, etc). These parameters may be configured as default parameters for any PCEP session the PCEP speaker participates in, or may apply to a specific session with a given PCEP peer or a specific group of sessions with a specific group of PCEP peers. 6.2. Information and Data Models, e.g. MIB module Extensions to the PCEP MIB module defined in [PCEP-MIB] should be defined, so as to cover the WSON RWA information introduced in this document. A future revision of this document will list the information that should be added to the MIB module. 6.3. Liveness Detection and Monitoring Mechanisms defined in this document do not imply any new liveness detection and monitoring requirements in addition to those already listed in section 8.3 of [RFC5440]. 6.4. Verifying Correct Operation Mechanisms defined in this document do not imply any new verification requirements in addition to those already listed in section 8.4 of [RFC5440] 6.5. Requirements on Other Protocols and Functional Components The PCE Discovery mechanisms ([RFC5089] and [RFC5088]) may be used to advertise WSON RWA path computation capabilities to PCCs. Lee & Casellas Expires January12,2014 [Page 16] Internet-Draft PCEP Extension for WSON RWA July 2013 6.6. Impact on Network Operation Mechanisms defined in this document do not imply any new network operation requirements in addition to those already listed in section 8.6 of [RFC5440]. 7. Security Considerations This document has no requirement for a change to the security models within PCEP [PCEP]. However the additional information distributed in order to address the RWA problem represents a disclosure of network capabilities that an operator may wish to keep private. Consideration should be given to securing this information. 8. IANA Considerations A future revision of this document will present requests to IANA for codepoint allocation. 9. Acknowledgments The authors would like to thank Adrian Farrel for many helpful comments that greatly improved the contents of this draft. This document was prepared using 2-Word-v2.0.template.dot. 10. References 10.1. Informative References [RFC 2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. [RFC3471] Berger, L., "Generalized Multi-Protocol Label Switching (GMPLS) Signaling Functional Description", RFC3471, January 2003. Lee & Casellas Expires January12,2014 [Page 17] Internet-Draft PCEP Extension for WSON RWA July 2013 [RFC3473] Berger, L., Ed., "Generalized Multi-Protocol Label Switching (GMPLS) Signaling Resource ReserVation Protocol- Traffic Engineering (RSVP-TE) Extensions", RFC3473, January 2003. [RFC3477] Kompella, K. and Y. Rekhter, "Signalling Unnumbered Links in Resource ReSerVation Protocol - Traffic Engineering (RSVP-TE)", RFC3477, January 2003. [RFC4003] Berger, L., "GMPLS Signaling Procedure for Egress Control", RFC4003, February 2005. [RFC4655] Farrel, A., Vasseur, J., and J. Ash, "A Path Computation Element (PCE)-Based Architecture", RFC4655, August 2006. [RFC4657] Ash, J. and J. Le Roux, "Path Computation Element (PCE) Communication Protocol Generic Requirements", RFC4657, September 2006. [RFC5440] Vasseur, JP., Ed. and JL. Le Roux, Ed., "Path Computation Element (PCE) communication Protocol", RFC5440, March 2009. [PCEP-GMPLS] Margaria, et al., "PCEP extensions for GMPLS", draft- ietf-pce-gmpls-pcep-extensions, work in progress. [LSPA-ERO] Margaria, et al., "LSP Attribute in ERO", draft-margaria- ccamp-lsp-attribute-ero, work in progress. [PCEP-Layer] Oki, Takeda, Le Roux, and Farrel, "Extensions to the Path Computation Element communication Protocol (PCEP) for Inter-Layer MPLS and GMPLS Traffic Engineering", draft- ietf-pce-inter-layer-ext, work in progress. [RFC6163] Lee, Y. and Bernstein, G. (Editors), and W. Imajuku, "Framework for GMPLS and PCE Control of Wavelength Switched Optical Networks", RFC6163, March 2011. [PCE-RWA] Lee, Y., et. al., "PCEP Requirements for WSON Routing and Wavelength Assignment", draft-ietf-pce-wson-routing- wavelength, work in progress. [RFC6205] Tomohiro, O. and D. Li, "Generalized Labels for Lambda- Switching Capable Label Switching Routers", RFC6205, January, 2011. Lee & Casellas Expires January12,2014 [Page 18] Internet-Draft PCEP Extension for WSON RWA July 2013 [WSON-Sign] Bernstein et al,"Signaling Extensions for Wavelength Switched Optical Networks", draft-ietf-ccamp-wson- signaling, work in progress. [WSON-OSPF] Lee and Bernstein,"OSPF Enhancement for Signal and Network Element Compatibility for Wavelength Switched Optical Networks",draft-ietf-ccamp-wson-signal- compatibility-ospf, work in progress. [RWA-Info] Bernstein and Lee, "Routing and Wavelength Assignment Information Model for Wavelength Switched Optical Networks",draft-ietf-ccamp-rwa-info, work in progress. [RWA-Encode]Bernstein and Lee, "Routing and Wavelength Assignment Information Encoding for Wavelength Switched Optical Networks",draft-ietf-ccamp-rwa-wson-encode, work in progress. [GEN-Encode] Bernstein and Lee, "General Network Element Constraint Encoding for GMPLS Controlled Networks",draft-ietf-ccamp- general-constraint-encode, work in progress. [WSON-Imp] Y. Lee, G. Bernstein, D. Li, G. Martinelli, "A Framework for the Control of Wavelength Switched Optical Networks (WSON) with Impairments", draft-ietf-ccamp-wson- impairments, work in progress. [RSVP-Imp] agraz, "RSVP-TE Extensions in Support of Impairment Aware Routing and Wavelength Assignment in Wavelength Switched Optical Networks WSONs)", draft-agraz-ccamp-wson- impairment-rsvp, work in progress. [OSPF-Imp] Bellagamba, et al., "OSPF Extensions for Wavelength Switched Optical Networks (WSON) with Impairments",draft- eb-ccamp-ospf-wson-impairments, work in progress. 11. Contributors Lee & Casellas Expires January12,2014 [Page 19] Internet-Draft PCEP Extension for WSON RWA July 2013 Authors' Addresses Young Lee, Editor Huawei Technologies 1700 Alma Drive, Suite 100 Plano, TX 75075, USA Phone: (972) 509-5599 (x2240) Email: email@example.com Ramon Casellas, Editor CTTC PMT Ed B4 Av. Carl Friedrich Gauss 7 08860 Castelldefels (Barcelona) Spain Phone: (34) 936452916 Email: firstname.lastname@example.org Fatai Zhang Huawei Technologies Email: email@example.com Cyril Margaria Nokia Siemens Networks St Martin Strasse 76 Munich, 81541 Germany Phone: +49 89 5159 16934 Email: firstname.lastname@example.org Oscar Gonzalez de Dios Telefonica Investigacion y Desarrollo C/ Emilio Vargas 6 Madrid, 28043 Spain Phone: +34 91 3374013 Email: email@example.com Greg Bernstein Grotto Networking Fremont, CA, USA Phone: (510) 573-2237 Email: firstname.lastname@example.org Intellectual Property Statement Lee & Casellas Expires January12,2014 [Page 20] Internet-Draft PCEP Extension for WSON RWA July 2013 The IETF Trust takes no position regarding the validity or scope of any Intellectual Property Rights or other rights that might be claimed to pertain to the implementation or use of the technology described in any IETF Document or the extent to which any license under such rights might or might not be available; nor does it represent that it has made any independent effort to identify any such rights. 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Disclaimer of Validity All IETF Documents and the information contained therein are provided on an "AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY, THE IETF TRUST AND THE INTERNET ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION THEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. Acknowledgment Funding for the RFC Editor function is currently provided by the Internet Society. Lee & Casellas Expires January12,2014 [Page 21]