--- 1/draft-ietf-pce-wson-rwa-ext-00.txt 2013-07-12 10:14:24.522074613 -0700 +++ 2/draft-ietf-pce-wson-rwa-ext-01.txt 2013-07-12 10:14:24.562075622 -0700 @@ -1,25 +1,25 @@ Network Working Group Y. Lee, Ed. Internet Draft Huawei Technologies Intended status: Standard R. Casellas, Ed. -Expires: September 2013 CTTC +Expires: January 2014 CTTC - March 26, 2013 + July 12, 2013 PCEP Extension for WSON Routing and Wavelength Assignment - draft-ietf-pce-wson-rwa-ext-00.txt + draft-ietf-pce-wson-rwa-ext-01.txt Abstract - This draft provides the Path Computation Element communication + 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 @@ -34,21 +34,21 @@ Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress." The list of current Internet-Drafts can be accessed at http://www.ietf.org/ietf/1id-abstracts.txt The list of Internet-Draft Shadow Directories can be accessed at http://www.ietf.org/shadow.html. - This Internet-Draft will expire on August 26, 2013. + 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 @@ -59,75 +59,75 @@ 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 sub-TLV.............................11 - 4.2.2. Wavelength Restriction Field sub-TLV................12 + 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..........................................15 + 5.1. Error Indicator..........................................14 5.2. NO-PATH Indicator........................................15 - 6. Manageability Considerations..................................16 - 6.1. Control of Function and Policy...........................16 + 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..............................17 - 6.5. Requirements on Other Protocols and Functional Components17 + 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 8. IANA Considerations...........................................17 9. Acknowledgments...............................................17 - 10. References...................................................18 - 10.1. Informative References..................................18 - 11. Contributors.................................................20 - Authors' Addresses...............................................21 - Intellectual Property Statement..................................21 - Disclaimer of Validity...........................................22 + 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 [RFC2119]. 3. Introduction - [RFC4655] defines the PCE based 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. + [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 PCC and 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. + 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 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 @@ -177,79 +177,73 @@ 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, 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 + 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 constraint - 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. + 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. 4. Encoding of a RWA Path Request Figure 2 shows one typical PCE based implementation, which is - referred to as 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 + 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 - The current RP object is used to indicate routing related - information in a new path request per [RFC5440]. Since a new RWA - path request involves both routing and wavelength assignment, the - wavelength assignment related information in the request SHOULD be - coupled in the path request. - 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. @@ -271,53 +265,57 @@ ::=[] ::= [other optional objects...] - If WA object is present in the request, the WA object MUST be - encoded after the ENDPOINTS object. + 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 + + . 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. - O (Order - 3 bits): O bit is used to indicate the wavelength + . 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 @@ -339,105 +337,98 @@ 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. - [Ed note: Which PCEP Object will home this TLV is yet to be - determined. Since this involves the end-point, The END-POINTS Object - might be a good candidate to encode this TLV, which will be provided - in a later revision.] - - [Ed note: The current encoding assumes that tunability restriction - applied to link-level.] - 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: ::= - - + ( )... Where - ::= + ::= [] + + ::= | | 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 | Format | Reserved | + | 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 + . 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. - 1 - Inclusive Range indicates that the Link Set defines a + . 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 Format: The format of the link identifier (8 bits) + o Count: The number of of the link identifiers (8 bits) - 0 -- Unnumbered Link Identifier - 1 -- Local Interface IPv4 Address - 2 -- Local Interface IPv6 Address - Others TBD. + 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. See the - following section for Link Identifier encoding. + 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 sub-TLV + 4.2.1. Link Identifier Entry The link identifier field can be an IPv4, IPv6 or unnumbered interface ID. ::= | | The encoding of each case is as follows: - IPv4 prefix Sub-TLV + 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 @@ -453,30 +444,28 @@ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | 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 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+- - - 4.2.2. Wavelength Restriction Field sub-TLV + 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 @@ -495,42 +484,43 @@ 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 + . Optical Interface Class List - Client signal + . 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]. In order to support the Optical Interface Class information a new - TLV are introduced as endpoint-restriction in the END-POINTS type + TLV is introduced as endpoint-restriction in the END-POINTS type Generalized endpoint: - Optical Interface Class List TLV + . Optical Interface Class List TLV - The END-POINTS type generalized endpoint is extended as follow: + The END-POINTS type generalized endpoint is extended as follows: ::= - + [...] Where signal-compatibility-restriction ::= The encoding for Optical Interface Class List is described in @@ -591,74 +580,69 @@ 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: - Error-Type=TBD; Error-value=1: if a PCE receives a RWA request + . 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 + . 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=15) + 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 PCRep message. - 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. - - Two new bit flags 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 associated with RWA. + 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. - Bit TDB: When set, the PCE indicates that no wavelength was - assigned to at least one hop of the route in the response. + 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 indicate that no path was found - satisfying the signal compatibility constraints. + . 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: - The ability to send a WSON RWA request. + . 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. + . The support for WSON RWA. - A set of WSON RWA specific policies (authorized sender, + . 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