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Versions: (draft-otani-pce-gmpls-aps-req) 00 01 02 03 04 05 06 07 08 09 RFC 7025

Network Working Group                                     Tomohiro Otani
Internet Draft                                                      KDDI
Intended status: Informational                             Kenichi Ogaki
                                                           KDDI R&D Labs
                                                          Diego Caviglia
                                                                Ericsson
                                                             Fatai Zhang
                                                                  Huawei
Expires: January 2011                                       July 6, 2010


               Requirements for GMPLS applications of PCE

               Document: draft-ietf-pce-gmpls-aps-req-02.txt




Status of this Memo

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   This Internet-Draft will expire on January 5, 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).



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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.................................................2
   2. Terminology..................................................3
   3. GMPLS applications of PCE....................................3
      3.1. GMPLS network model.....................................3
      3.2. Path computation in GMPLS network.......................3
      3.3. Unnumbered Interface....................................5
      3.4. Asymmetric Bandwidth Path Computation...................6
   4. Requirement for GMPLS application of PCE.....................6
      4.1. PCE requirements........................................6
      4.2. PCC requirements........................................7
      4.3. GMPLS PCE Management....................................7
   5. Security consideration.......................................7
   6. IANA Considerations..........................................7
   7. Acknowledgement..............................................7
   8. References...................................................7
   9. Authors' Addresses...........................................9

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 consideration 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.

   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


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   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, assumed in this document. D1, D2, D3 and D4 have multiple
   GMPLS inter-domain connections, and D5 has only one GMPLS inter-
   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.


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             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 table of switching capability, encoding
   type and bandwidth at the ingress link, transiting links and the
   egress link which need to be satisfied with 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.















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                     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, 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 Interface

   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 Path 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.





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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. Requirement for GMPLS application of PCE

   In this section, we describe requirements for GMPLS applications of
   PCE in order to establish GMPLS LSP.

4.1. PCE requirements

   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 attributes to those already
   defined in [PCECP] are as follows.

  (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].

  (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 Concatenation information.

  (5) Concatenation Number: Indicates the number of signals that are
      requested to be contiguously or virtually concatenated. Also see
      [RFC4606] and [RFC4328].


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  (6) Wavelength Label: as defined in [Lambda-label].

  (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].

4.2. PCC requirements

   As described above, a PCC needs to support to initiate path
   computation request specifying abovementioned attributes. Afterwards,
   GMPLS signaling will be invoked according to the responded messages
   from the PCE.

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.




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[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.

[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, 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]     J.P. Vasseur, et al, "Path Computation Element (PCE)
            Communication Protocol (PCEP)", RFC5440, March 2009.

[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-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.


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[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-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.

[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:  tm-otani@kddi.com

   Kenichi Ogaki
   KDDI R&D Laboratories, Inc.
   2-1-15 Ohara Fujimino-shi, Saitama 356-8502 Japan
   Phone:  +81-49-278-7897
   Email:  ogaki@kddilabs.jp

   Diego Caviglia
   Ericsson
   16153 Genova Cornigliano, ITALY
   Phone: +390106003736
   Email: diego.caviglia@ericsson.com

   Fatai Zhang
   Huawei Technologies Co., Ltd.
   F3-5-B R&D Center, Huawei Base,


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   Bantian, Longgang District
   Shenzhen 518129 P.R.China
   Phone: +86-755-28972912
   Email: zhangfatai@huawei.com

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