Network Working Group Tomohiro Otani Internet Draft KDDI Intended status: Informational Kenichi Ogaki KDDI R&D Labs Diego Caviglia Ericsson Fatai Zhang Huawei Expires:
April 20,November 30, 2011 October 20, 2010May 30,2011 Requirements for GMPLS applications of PCE Document: draft-ietf-pce-gmpls-aps-req-03.txtdraft-ietf-pce-gmpls-aps-req-04.txt 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. The list of Internet-Draft Shadow Directories can be accessed at http://www.ietf.org/shadow.html. This Internet-Draft will expire on April 20,November 30, 2011. Abstract The initial effort of PCE WG is specifically focused on MPLS (Multi- protocol label switching). As a next step, this draft describes functional requirements for GMPLS (Generalized MPLS) application of PCE (Path computation element). Conventions used in this document The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in [RFC2119]. Table of Contents 1. Introduction.................................................2Introduction ................................................ 2 2. Terminology..................................................3Terminology ................................................. 3 3. GMPLS applications of PCE....................................3PCE.................................... 3 3.1. GMPLS network model.....................................3model..................................... 3 3.2. Path computation in GMPLS network.......................4network .......................4 3.3. Unnumbered Interface....................................5Interface.................................... 6 3.4. Asymmetric Bandwidth Path Computation...................6Computation ...................6 4. Requirements for GMPLS applicationapplications of PCE....................6PCE ...................6 4.1. Requirements of Path Computation Request................6Request ................6 4.2. Requirements of Path Computation Reply..................7Reply ..................7 4.3. GMPLS PCE Management....................................8Management.................................... 8 5. Security consideration.......................................8consideration....................................... 8 6. IANA Considerations..........................................8Considerations ......................................... 9 7. Acknowledgement..............................................8Acknowledgement ............................................. 9 8. References...................................................8References .................................................. 9 9. Authors' Addresses..........................................10Addresses ......................................... 11 1. Introduction The initial effort of PCE WG is focused on solving the path computation problem over different domains in MPLS networks. As the same case with MPLS, service providers (SPs) have also come up with requirements for path computation in GMPLS networks such as photonics, TDM-based or Ethernet-based networks as well. [PCE-ARCH] and [PCECP-REQ] discuss the framework and requirements for PCE on both packet MPLS networks and (non-packet switch capable) GMPLS networks. This document complements these documents by providing some considerationconsiderations of GMPLS applications in the intra- domain and inter-domain networking environments and indicating a set of requirements for the extended definition of series of PCE related protocols. Note that the requirements for inter-layer traffic engineering described in [PCE-INTER LAYER-REQ] are outside of the scope of this document. Constraint based shortest path first (CSPF) computation within a domain or over domains for signaling GMPLS Label Switched Paths (LSPs) is more stringent than that of MPLS LSPs [MPLS-AS], because the additional constraints, e.g., interface switching capability, link encoding, link protection capability and so forth need to be considered to establish GMPLS LSPs [CSPF]. GMPLS signaling protocol [RFC3471, RFC3473] is designed taking into account bi-directionality, switching type, encoding type, SRLG, and protection attributes of the TE links spanned by the path, as well as LSP encoding and switching type for the end points, appropriately. This document provides the investigated results of GMPLS applications of PCE for the support of GMPLS path computation. This document also provides requirements for GMPLS applications of PCE in the GMPLS intra-domain and inter-domain environments. 2. Terminology 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. GMPLS applications of PCE 3.1. GMPLS network model Figure 1 depicts a typical network, consisting of several GMPLS domains,GMPLSdomains, assumed in this document. D1, D2, D3 and D4 have multiple GMPLS inter-domain connections, andwhile D5 has only one GMPLS inter- domaininter-domain connection. These domains follow the definition in [RFC4726]. +---------+ +---------|GMPLS D2|----------+ | +----+----+ | +----+----+ | +----+----+ +---------+ |GMPLS D1| | |GMPLS D4|---|GMPLS D5| +----+----+ | +----+----+ +---------+ | +----+----+ | +---------|GMPLS D3|----------+ +---------+ Figure 1: GMPLS Inter-domain network model. Each domain is configured using various switching and link technologies defined in [Arch] and an end-to-end route needs to respect TE link attributes like switching capability, encoding type, etc., making the problem a bit different from the case of classical (packet) MPLS. In order to route from one GMPLS domain to another GMPLS domain appropriately, each domain manages traffic engineering database (TED) by PCE, and exchanges or provides route information of paths, while concealing its internal topology information. 3.2. Path computation in GMPLS network [CSPF] describes consideration of GMPLS TE attributes during path computation. Figure 2 depicts a typical GMPLS network, consisting of an ingress link, a transit link as well as an egress link, to investigate a consistent guideline for GMPLS path computation. Each link at each interface has its own switching capability, encoding type and bandwidth. Ingress Transit Egress +-----+ link1-2 +-----+ link2-3 +-----+ link3-4 +-----+ |Node1|------------>|Node2|------------>|Node3|------------>|Node4| | |<------------| |<------------| |<------------| | +-----+ link2-1 +-----+ link3-2 +-----+ link4-3 +-----+ Figure 2: Path computation in GMPLS networks. For the simplicity in consideration, the below basic assumptions are made when the LSP is created. (1) Switching capabilities of outgoing links from the ingress and egress nodes (link1-2 and link4-3 in Figure 2) must be consistent with each other. (2) Switching capabilities of all transit links including incoming links to the ingress and egress nodes (link2-1 and link3-4) should be consistent with switching type of a LSP to be created. (3) Encoding-types of all transit links should be consistent with encoding type of a LSP to be created. [CSPF] indicates the possible tabletables of switching capability, encoding type and bandwidth at the ingress link, transiting links and the egress link which need to be satisfied with GMPLS path computation of the created LSP. The non-packet GMPLS networks (e.g., TDM networks) are usually responsible for transmitting data for the client layer. These GMPLS networks can provide different types of connections for customer services based on different service bandwidth requests. The applications and the corresponding additional requirements for applying PCE in non-packet networks, for example, GMPLS-based TDM networks, are described in Figure 3. In order to simplify the description, this document just discusses the scenario in SDH networks as an example. The scenarios in SONET or G.709 ODUk layer networks are similar. N1 N2 +-----+ +------+ +------+ | |-------| |--------------| | +-------+ +-----+ | |---| | | | | A1 +------+ | +------+ | | | | | +-------+ | | | PCE | | | | +------+ | | | | | | | |-----| | | +------+ | | | N5 | | | | | +------+ +------+ | | | | +-----+ | |--------------| |--------| | +------+ +------+ +-----+ N3 N4 A2 Figure 3: A simple SDH network Figure 3 shows a simple network topology, where N1, N2, N3, N4,N4 and N5 are all SDH switches. Assume that one Ethernet service with 100M bandwidth is required from A1 to A2 over this network. The client Ethernet service could be provided by a VC4 connection from N1 to N4, and it could also be provided by three concatenated VC3 connections (Contiguous or Virtual concatenation) from N1 to N4. The type of connection(s) (one VC4 or three concatenated VC3) that is required needs to be specified by PCC (e.g., N1 or NMS), but could also be determined by PCE automatically based on policy [RFC5394]. Therefore, the signal type, the type of the concatenation and the number of the concatenation should also be considered during path computation for PCE. 3.3. Unnumbered InterfaceInterfaces GMPLS support unnumbered interface ID that is defined in [RFC 3477], which means that the endpoints of the path may be unnumbered. It should also be possible to request a Pathpath between a numbered link and an unnumbered link, or a P2MP path between different types of endpoints. Therefore, the PCC should be capable of indicating the unnumbered interface ID of the endpoints in the PCReq message. 3.4. Asymmetric Bandwidth Path Computation As per [RFC 5467], GMPLS signaling can be used for setting up an asymmetric bandwidth bidirectional LSP. If a PCE is responsible for the path computation, the PCE should be capable of computing a path for the bidirectional LSP with asymmetric bandwidth. It means that the PCC should be able to indicate the asymmetric bandwidth requirements in forward and reverse directions in the PCReq message. 4. Requirements for GMPLS application of PCE In this section, we describe requirements for GMPLS applications of PCE in order to establish GMPLS LSP. 4.1. Requirements of Path Computation Request As for path computation in GMPLS networks as discussed in section 3, the PCE needs to consider the GMPLS TE attributes appropriately according to tables in [CSPF] once a PCC or another PCE requests a path computation. Indeed, the path calculation request message from the PCC or the PCE needs to contain the information specifying appropriate attributes. Additional attributesAccording to those already defined in [PCECP][RFC5440],[PCEP-EXT],[ PCE-WSON- REQ] and to RSVP procedures like explicit label control(ELC),the additional attributes introduced are as follows.follows: [RFC5440] (1) Switching capability: PSC1-4, L2SC, DCSC [DCSC-Ext], 802_1 PBB-TE [GMPLS-PBB-TE], 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. See [RFC4606] and [RFC4328].See[RFC4606] , [RFC4328]and [OSPF-G709] or [RSVP-TE- G709]. (4) Concatenation Type: In SDH/SONET and G.709 ODUk 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] and [RFC4328] about Concatenationconcatenation information. (5) Concatenation Number: Indicates the number of signals that are requested to be contiguously or virtually concatenated. Also see [RFC4606] and [RFC4328]. (6) Wavelength Label:Technology specific label(s) such as wavelength label as defined in [Lambda-label].[RFC6205]. (7) e2e Path protection type: as defined in [RFC4872], e.g., 1+1 protection, 1:1 protection, (pre-planned) rerouting, etc. (8) Administrative group: as defined in [RFC3630]. (9) Link Protection type: as defined in [RFC4203]. (10)Support for unnumbered interfaces: as defined in [RFC3477]. (11)Support for asymmetric bandwidth request: as defined in [RFC 5467]. (12)Support for explicit label control during the path computation. 4.2. Requirements of Path Computation Reply As described above, a PCC needs to support to initiate a PCReq message specifying above mentioned attributes. The PCE needs to compute the path that satisfies the constraints which are specified in the PCReq message. Then the PCE needs to send a PCRep message including the computation result to the PCC. For Path Computation Reply message (PCRep) in GMPLS networks, there are some additional requirements. The PCEP PCRep message needs to be extended to meet the following requirements. (1) Concatenation path computation In the case of concatenation path computation, when a PCE receives the PCReq message specifying the concatenation constraints described in section 4.1, the PCE should compute the path which satisfies the specified concatenation constraints. For contiguous concatenation path computation, the routes of each member signal must be co-routed and all the interfaces along the route should support contiguous concatenation capability. Therefore, the PCE needs to compute a path based on the contiguous concatenation capability of each interface and only one ERO which carries the route information is needed for the response. For virtual concatenation path computation, only the ingress/egress interfaces need to support virtual concatenation capability and maybe there are diverse routes for the different member signals. Therefore, multiple EROs may be needed for the response. Each ERO may represent the route of one or multiple member signals. In the case that one ERO represents several member signals among the total member signals, the number of member signals along the route of the ERO needs to be specified. (2) Wavelength label In the case that a PCC doesn't specify the wavelength when requesting a wavelength path and the PCE is capable of performing the route and wavelength computation procedure, the PCE needs to be able to specify the wavelength of the path in a PCRep message. (3) Roles of the routes When a PCC specifies the protection type of the LSPs, the PCE needs to compute the working route and the corresponding protection route(s). Therefore, the PCRep should be capable of indicate which one is working or protection route. 4.3. GMPLS PCE Management PCE related Management Information Bases need to consider extensions to be satisfied with requirements for GMPLS applications. For extensions, [GMPLS-TEMIB] are defined to manage TE database and may be referred to accommodate GMPLS TE attributes in the PCE. 5. Security consideration PCE extensions to support GMPLS should be considered under the same security as current work. This extension will not change the underlying security issues. 6. IANA Considerations This document has no actions for IANA. 7. Acknowledgement The author would like to express the thanks to Shuichi Okamoto for his comments. 8. References [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. [PCE-ARCH] A. Farrel, et al, "A Path Computation Element (PCE)-Based Architecture", RFC4655, Aug., 2006. [PCECP-REQ] J. Ash, et al, "Path computation element (PCE) communication protocol generic requirements", RFC4657, Sept., 2007. [PCE-INTER LAYER-REQ] T.Takeda,et al,"PCC-PCE Communication and PCE Discovery Requirements for Inter-Layer Engineering",December 2010. [MPLS-AS] R. Zhan, et al, "MPLS Inter-Autonomous System (AS) Traffic Engineering (TE) Requirements", RFC4216, November 2005. [CSPF] T. Otani, et al, "Considering Generalized Multiprotocol Label Switching Traffic Engineering Attributes During Path Computation", draft-otani-ccamp-gmpls-cspf-constraints- 07.txt,draft-otani-ccamp-gmpls-cspf- constraints-07.txt, Feb., 2008. [RFC3471] Berger, L., "Generalized Multi-Protocol Label Switching (MPLS) Signaling Functional Description", RFC 3471, January 2003. [RFC3473] Berger, L., "Generalized Multi-Protocol Label Switching (MPLS) Signaling - Resource ReserVation Protocol Traffic Engineering (RSVP-TE) Extensions", RFC 3473, January 2003. [RFC4726] A. Farrel, et al, "A framework for inter-domain MPLS traffic engineering", RFC4726, November 2006. [Arch] E. Mannie, et al, "Generalized Multi-Protocol Label Switching Architecture", RFC3945, October, 2004. [PCECP][RFC5394] I.Bryskin,et al,"Policy-Enabled Path Computation Framework",RFC5394,December 2008. [RFC3477] K.Kompella,et al,"Signalling Unnumbered Links in Resource ReSerVation Protocol-Traffic Engineering(RSVP- TE)",January 2003. [RFC5476] B.Claise,Ed,"Packet Sampling(PSAMP) Protocol Specifications",March 2009. [RFC5440] J.P. Vasseur, et al, "Path Computation Element (PCE) Communication Protocol (PCEP)", RFC5440, March 2009. [PCEP-EXT] C.Margaria,et al, "PCEP extensions for GMPLS",draft- ietf-pce-gmpls-PCEP-EXTs-02.txt,March 2011. [PCE-WSON-REQ] Y.Lee, et al,"PCEP Requirements for WSON Routing and Wavelength Assignment",draft-ietf-pce-wson-routing- wavelength-04.txt,March 2011. [RFC4202] K. Kompella, and Y. Rekhter, "Routing Extensions in Support of Generalized Multi-Protocol Label Switching", RFC4202, Oct. 2005. [RFC4203] K. Kompella, and Y. Rekhter, "OSPF Extensions in Support of Generalized Multi-Protocol Label Switching", RFC4203, Oct. 2005. [RFC4872] J.P. Lang, Ed., "RSVP-TE Extensions in Support of End-to-EndEnd-to- End Generalized Multi-Protocol Label Switching (GMPLS) Recovery", RFC4872, May 2007. [GMPLS-TEMIB] T. Nadeau and A. Farrel, Ed., "Generalized Multiprotocol Label Switching (GMPLS) Traffic Engineering Management Information Base", RFC4802, Feb. 2007. [RFC3630] D. Katz et al., "Traffic Engineering (TE) Extensions to OSPF Version 2", RFC3630, September 2003. [Lambda-label] T. Otani, Ed., "Generalized Labels for G.694 Lambda- Switching Capable Label Switching Routers", draft-ietf- ccamp-gmpls-g-694-lambda-labels, in progress. [RFC5394] I. Bryskin et al., " Policy-Enabled Path Computation Framework", RFC5394, December 2008. [RFC4606] E. Mannie and D. Papadimitriou, "Generalized Multi-ProtocolMulti- Protocol Label Switching (GMPLS) Extensions for Synchronous Optical Network (SONET) and Synchronous Digital Hierarchy (SDH) Control", RFC4606, August 2006. [RFC4328] D. Papadimitriou, Ed., "Generalized Multi-Protocol Label Switching (GMPLS) Signaling Extensions for G.709 Optical Transport Networks Control", RFC4328, January 2006. [RFC3477] K.Kompella,"Signalling Unnumbered Links in Resource ReServation Protocol-Traffic Engineering(RSVP- TE)",January 2003. [OSPF-G709] D.Ceccarelli,et al,"Traffic Engineering Extensions to OSPF for Generalized MPLS(GMPLS) Control of Evolving G.709 OTN Networks",March 2011. [RSVP-TE-G709] Fatai Zhang,et al,"Generalized Multi-Protocol Label Switching(GMPLS) Signaling Extensions for the evolving G.709 Optical Transport Network Control",March 2011. [DCSC-Ext] Lou Berger, et al.,"Generalized MPLS (GMPLS) Data Channel Switching Capable (DCSC) and Channel Set Label Extensions", in progress. [GMPLS-PBB-TE] Don Fedyk, et al., "Generalized Multiprotocol Label Switching (GMPLS) control of Ethernet PBB-TE", in progress. 9. Authors' Addresses Tomohiro Otani KDDI Corporation 2-3-2 Nishi-shinjuku Shinjuku-ku, Tokyo 163-8003 Japan Phone: +81-3-3347-6006 Email: firstname.lastname@example.org Kenichi Ogaki KDDI R&D Laboratories, Inc. 2-1-15 Ohara Fujimino-shi, Saitama 356-8502 Japan Phone: +81-49-278-7897 Email: email@example.com Diego Caviglia Ericsson 16153 Genova Cornigliano, ITALY Phone: +390106003736 Email: firstname.lastname@example.org Fatai Zhang Huawei Technologies Co., Ltd. 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