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diff --git a/doc/rfc/rfc7025.txt b/doc/rfc/rfc7025.txt new file mode 100644 index 0000000..ea9c1c0 --- /dev/null +++ b/doc/rfc/rfc7025.txt @@ -0,0 +1,675 @@ + + + + + + +Internet Engineering Task Force (IETF) T. Otani +Request for Comments: 7025 K. Ogaki +Category: Informational KDDI +ISSN: 2070-1721 D. Caviglia + Ericsson + F. Zhang + Huawei Technologies + C. Margaria + Coriant R&D GmbH + September 2013 + + + Requirements for GMPLS Applications of PCE + +Abstract + + The initial effort of the PCE (Path Computation Element) WG focused + mainly on MPLS. As a next step, this document describes functional + requirements for GMPLS applications of PCE. + +Status of This Memo + + This document is not an Internet Standards Track specification; it is + published for informational purposes. + + This document is a product of the Internet Engineering Task Force + (IETF). It represents the consensus of the IETF community. It has + received public review and has been approved for publication by the + Internet Engineering Steering Group (IESG). Not all documents + approved by the IESG are a candidate for any level of Internet + Standard; see Section 2 of RFC 5741. + + Information about the current status of this document, any errata, + and how to provide feedback on it may be obtained at + http://www.rfc-editor.org/info/rfc7025. + + + + + + + + + + + + + + + + +Otani, et al. Informational [Page 1] + +RFC 7025 Reqs for GMPLS Apps of PCE September 2013 + + +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. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 2 + 2. GMPLS Applications of PCE . . . . . . . . . . . . . . . . . . 3 + 2.1. Path Computation in GMPLS Networks . . . . . . . . . . . . 3 + 2.2. Unnumbered Interface . . . . . . . . . . . . . . . . . . . 5 + 2.3. Asymmetric Bandwidth Path Computation . . . . . . . . . . 5 + 3. Requirements for GMPLS Applications of PCE . . . . . . . . . . 6 + 3.1. Requirements on Path Computation Request . . . . . . . . . 6 + 3.2. Requirements on Path Computation Reply . . . . . . . . . . 7 + 3.3. GMPLS PCE Management . . . . . . . . . . . . . . . . . . . 8 + 4. Security Considerations . . . . . . . . . . . . . . . . . . . 8 + 5. Acknowledgement . . . . . . . . . . . . . . . . . . . . . . . 9 + 6. References . . . . . . . . . . . . . . . . . . . . . . . . . . 9 + 6.1. Normative References . . . . . . . . . . . . . . . . . . . 9 + 6.2. Informative References . . . . . . . . . . . . . . . . . . 11 + +1. Introduction + + The initial effort of the PCE (Path Computation Element) WG focused + mainly on solving the path computation problem within a domain or + over different domains in MPLS networks. As with MPLS, service + providers (SPs) have also come up with requirements for path + computation in GMPLS-controlled networks [RFC3945], such as those + based on Wavelength Division Multiplexing (WDM), Time Division + Multiplexing (TDM), or Ethernet. + + [RFC4655] and [RFC4657] discuss the framework and requirements for + PCE on both packet MPLS networks and GMPLS-controlled networks. This + document complements those RFCs by providing considerations of GMPLS + applications in the intradomain and interdomain networking + environments and indicating a set of requirements for the extended + definition of PCE-related protocols. + + + +Otani, et al. Informational [Page 2] + +RFC 7025 Reqs for GMPLS Apps of PCE September 2013 + + + Note that the requirements for interlayer and inter-area traffic + engineering (TE) described in [RFC6457] and [RFC4927] are outside of + the scope of this document. + + Constrained Shortest Path First (CSPF) computation within a domain or + over domains for signaling GMPLS Label Switched Paths (LSPs) is + usually more stringent than that of MPLS TE LSPs [RFC4216], because + the additional constraints, e.g., interface switching capability, + link encoding, link protection capability, Shared Risk Link Group + (SRLG) [RFC4202], and so forth, need to be considered to establish + GMPLS LSPs. The GMPLS signaling protocol [RFC3473] is designed + taking into account bidirectionality, switching type, encoding type, + and protection attributes of the TE links spanned by the path, as + well as LSP encoding and switching type of the endpoints, + appropriately. + + This document provides requirements for GMPLS applications of PCE in + support of GMPLS path computation, included are requirements for both + intradomain and interdomain environments. + +2. GMPLS Applications of PCE + +2.1. Path Computation in GMPLS Networks + + Figure 1 depicts a model GMPLS network, consisting of an ingress + link, a transit link, as well as an egress link. We will use this + model to investigate consistent guidelines 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 1: Path Computation in GMPLS Networks + + For the simplicity in consideration, the following 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 1) are 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) are + consistent with switching type of an LSP to be created. + + + +Otani, et al. Informational [Page 3] + +RFC 7025 Reqs for GMPLS Apps of PCE September 2013 + + + (3) Encoding types of all transit links are consistent with the + encoding type of an LSP to be created. + + GMPLS-controlled networks (e.g., GMPLS-based TDM networks) are + usually responsible for transmitting data for the client layer. + These GMPLS-controlled 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 to GMPLS-based TDM networks are described in this + section. In order to simplify the description, this document only + discusses the scenario in Synchronous Digital Hierarchy (SDH) + networks as an example (see Figure 2). The scenarios in Synchronous + Optical Network (SONET) or Optical Transport Network (OTN) are + similar. + + N1 N2 + +-----+ +------+ +------+ + | |-------| |--------------| | +-------+ + +-----+ | |---| | | | | + A1 +------+ | +------+ | | + | | | +-------+ + | | | PCE + | | | + | +------+ | + | | | | + | | |-----| | + | +------+ | | + | N5 | | + | | | + +------+ +------+ + | | | | +-----+ + | |--------------| |--------| | + +------+ +------+ +-----+ + N3 N4 A2 + + Figure 2: A Simple TDM (SDH) Network + + Figure 2 shows a simple TDM (SDH) network topology, where N1, N2, N3, + N4, and N5 are all SDH switches; A1 and A2 are client devices (e.g., + Ethernet switches). Assume that one Ethernet service with 100 Mbit/s + bandwidth is required from A1 to A2 over this network. The client + Ethernet service could be provided by a Virtual Container 4 (VC-4) + container from N1 to N4; it could also be provided by three + concatenated VC-3s (contiguous or virtual concatenation) from N1 to + N4. + + + + +Otani, et al. Informational [Page 4] + +RFC 7025 Reqs for GMPLS Apps of PCE September 2013 + + + In this scenario, when the ingress node (e.g., N1) receives a client + service transmitting request, the type of containers (one VC-4 or + three concatenated VC-3s) could be determined by the PCC (Path + Computation Client), e.g., N1 or Network Management System (NMS). + However, it could also be determined automatically by the PCE based + on policy [RFC5394]. If it is determined by the PCC, then the PCC + should be capable of specifying the ingress node and egress node, + signal type, the type of the concatenation, and the number of the + concatenation in a PCReq (Path Computation Request) message. The PCE + should consider those parameters during path computation. The route + information (co-routing or diverse routing) should be specified in a + PCRep (Path Computation Reply) message if path computation is + performed successfully. + + As described above, the PCC should be capable of specifying TE + attributes defined in the next section, and the PCE should compute a + path accordingly. + + Where a GMPLS network consists of interdomain (e.g., inter-AS or + inter-area) GMPLS-controlled networks, requirements on the path + computation follow [RFC5376] and [RFC4726]. + +2.2. Unnumbered Interface + + GMPLS supports unnumbered interface IDs as defined in [RFC3477]; this + means that the endpoints of the path may be unnumbered. It should + also be possible to request a path consisting of the mixture of + numbered links and unnumbered links, or a P2MP (Point-to-Multipoint) + path with different types of endpoints. Therefore, the PCC should be + capable of indicating the unnumbered interface ID of the endpoints in + the PCReq message. + +2.3. Asymmetric Bandwidth Path Computation + + Per [RFC6387], GMPLS signaling can be used for setting up an + asymmetric bandwidth bidirectional LSP. If a PCE is responsible for + path computation, it should be capable of computing a path for the + bidirectional LSP with asymmetric bandwidth. This means that the PCC + should be able to indicate the asymmetric bandwidth requirements in + forward and reverse directions in the PCReq message. + + + + + + + + + + + +Otani, et al. Informational [Page 5] + +RFC 7025 Reqs for GMPLS Apps of PCE September 2013 + + +3. Requirements for GMPLS Applications of PCE + +3.1. Requirements on Path Computation Request + + As for path computation in GMPLS-controlled networks as discussed in + Section 2, the PCE should appropriately consider the GMPLS TE + attributes listed below once a PCC or another PCE requests a path + computation. The path calculation request message from the PCC or + the PCE must contain the information specifying appropriate + attributes. According to [RFC5440], [PCE-WSON-REQ], and RSVP + procedures such as explicit label control (ELC), the additional + attributes introduced are as follows: + + (1) Switching capability/type: as defined in [RFC3471], [RFC4203], + and all current and future values. + + (2) Encoding type: as defined in [RFC3471], [RFC4203], and all + current and future values. + + (3) Signal type: as defined in [RFC4606] and all current and future + values. + + (4) Concatenation type: In SDH/SONET and OTN, two kinds of + concatenation modes are defined: contiguous concatenation, + which requires co-routing for each member signal and that all + the interfaces along the path support this capability, and + virtual concatenation, which allows diverse routing for member + signals and requires that only the ingress and egress + interfaces support this capability. Note that for the virtual + concatenation, it may also specify co-routing or diverse + routing. 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]. + + (6) Technology-specific label(s): as defined in [RFC4606], + [RFC6060], [RFC6002], or [RFC6205]. + + (7) End-to-End (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]. + + + + +Otani, et al. Informational [Page 6] + +RFC 7025 Reqs for GMPLS Apps of PCE September 2013 + + + (10) Support for unnumbered interfaces: as defined in [RFC3477]. + + (11) Support for asymmetric bandwidth requests: as defined in + [RFC6387]. + + (12) Support for explicit label control during the path computation. + + (13) Support of label restrictions in the requests/responses, + similar to RSVP-TE ERO (Explicit Route Object) and XRO (Exclude + Route Object), as defined in [RFC3473] and [RFC4874]. + +3.2. Requirements on Path Computation Reply + + As described above, a PCE should compute the path that satisfies the + constraints specified in the PCReq message. Then, the PCE should + send a PCRep message, including the computation result, to the PCC. + For a Path Computation Reply message (PCRep) in GMPLS networks, there + are some additional requirements. The PCEP (PCE communication + protocol) PCRep message must be extended to meet the following + requirements. + + (1) Path computation with concatenation + + In the case of path computation involving concatenation, when a + PCE receives the PCReq message specifying the concatenation + constraints described in Section 3.1, the PCE should compute a + path accordingly. + + For path computation involving contiguous concatenation, a + single route is required, and all the interfaces along the route + should support contiguous concatenation capability. Therefore, + the PCE should compute a path based on the contiguous + concatenation capability of each interface and only one ERO that + should carry the route information for the response. + + For path computation involving virtual concatenation, only the + ingress/egress interfaces need to support virtual concatenation + capability, and there may be 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. When one ERO represents multiple member + signals, the number must be specified. + + + + + + + + + +Otani, et al. Informational [Page 7] + +RFC 7025 Reqs for GMPLS Apps of PCE September 2013 + + + (2) Label constraint + + In the case that a PCC does not specify the exact label(s) when + requesting a label-restricted path and the PCE is capable of + performing the route computation and label assignment + computation procedure, the PCE needs to be able to specify the + label of the path in a PCRep message. + + Wavelength restriction is a typical case of label restriction. + More generally, label switching and selection constraints may + apply in GMPLS-controlled networks, and a PCC may request a PCE + to take label constraint into account and return an ERO + containing the label or set of labels that fulfill the PCC + request. + + (3) Roles of the routes + + When a PCC specifies the protection type of an LSP, the PCE + should compute the working route and the corresponding + protection route(s). Therefore, the PCRep should allow to + distinguish the working (nominal) and the protection routes. + According to these routes, the RSVP-TE procedure appropriately + creates both the working and the protection LSPs, for example, + with the ASSOCIATION object [RFC6689]. + +3.3. GMPLS PCE Management + + This document does not change any of the management or operational + details for networks that utilize PCE. (Please refer to [RFC4655] + for manageability considerations for a PCE-based architecture.) + However, this document proposes the introduction of several PCEP + objects and data for the better integration of PCE with GMPLS + networks. Those protocol elements will need to be visible in any + management tools that apply to the PCE, PCC, and PCEP. That + includes, but is not limited to, adding appropriate objects to + existing PCE MIB modules that are used for modeling and monitoring + PCEP deployments [PCEP-MIB]. Ideas for what objects are needed may + be guided by the relevant GMPLS extensions in GMPLS-TE-STD-MIB + [RFC4802]. + +4. Security Considerations + + PCEP extensions to support GMPLS should be considered under the same + security as current PCE work, and this extension will not change the + underlying security issues. Section 10 of [RFC5440] describes the + list of security considerations in PCEP. At the time [RFC5440] was + published, TCP Authentication Option (TCP-AO) had not been fully + + + + +Otani, et al. Informational [Page 8] + +RFC 7025 Reqs for GMPLS Apps of PCE September 2013 + + + specified for securing the TCP connections that underlie PCEP + sessions. TCP-AO [RFC5925] has now been published, and PCEP + implementations should fully support TCP-AO according to [RFC6952]. + +5. Acknowledgement + + The authors would like to express thanks to Ramon Casellas, Julien + Meuric, Adrian Farrel, Yaron Sheffer, and Shuichi Okamoto for their + comments. + +6. References + +6.1. Normative References + + [RFC3471] Berger, L., "Generalized Multi-Protocol Label Switching + (GMPLS) Signaling Functional Description", RFC 3471, + January 2003. + + [RFC3473] Berger, L., "Generalized Multi-Protocol Label Switching + (GMPLS) Signaling Resource ReserVation Protocol-Traffic + Engineering (RSVP-TE) Extensions", RFC 3473, January 2003. + + [RFC3477] Kompella, K. and Y. Rekhter, "Signalling Unnumbered Links + in Resource ReSerVation Protocol - Traffic Engineering + (RSVP-TE)", RFC 3477, January 2003. + + [RFC3630] Katz, D., Kompella, K., and D. Yeung, "Traffic Engineering + (TE) Extensions to OSPF Version 2", RFC 3630, + September 2003. + + [RFC3945] Mannie, E., "Generalized Multi-Protocol Label Switching + (GMPLS) Architecture", RFC 3945, October 2004. + + [RFC4202] Kompella, K. and Y. Rekhter, "Routing Extensions in + Support of Generalized Multi-Protocol Label Switching + (GMPLS)", RFC 4202, October 2005. + + [RFC4203] Kompella, K. and Y. Rekhter, "OSPF Extensions in Support + of Generalized Multi-Protocol Label Switching (GMPLS)", + RFC 4203, October 2005. + + [RFC4328] Papadimitriou, D., "Generalized Multi-Protocol Label + Switching (GMPLS) Signaling Extensions for G.709 Optical + Transport Networks Control", RFC 4328, January 2006. + + + + + + + +Otani, et al. Informational [Page 9] + +RFC 7025 Reqs for GMPLS Apps of PCE September 2013 + + + [RFC4606] Mannie, E. and D. Papadimitriou, "Generalized Multi- + Protocol Label Switching (GMPLS) Extensions for + Synchronous Optical Network (SONET) and Synchronous + Digital Hierarchy (SDH) Control", RFC 4606, August 2006. + + [RFC4802] Nadeau, T. and A. Farrel, "Generalized Multiprotocol Label + Switching (GMPLS) Traffic Engineering Management + Information Base", RFC 4802, February 2007. + + [RFC4872] Lang, J., Rekhter, Y., and D. Papadimitriou, "RSVP-TE + Extensions in Support of End-to-End Generalized Multi- + Protocol Label Switching (GMPLS) Recovery", RFC 4872, + May 2007. + + [RFC4927] Le Roux, J., "Path Computation Element Communication + Protocol (PCECP) Specific Requirements for Inter-Area MPLS + and GMPLS Traffic Engineering", RFC 4927, June 2007. + + [RFC5376] Bitar, N., Zhang, R., and K. Kumaki, "Inter-AS + Requirements for the Path Computation Element + Communication Protocol (PCECP)", RFC 5376, November 2008. + + [RFC5440] Vasseur, JP. and JL. Le Roux, "Path Computation Element + (PCE) Communication Protocol (PCEP)", RFC 5440, + March 2009. + + [RFC6002] Berger, L. and D. Fedyk, "Generalized MPLS (GMPLS) Data + Channel Switching Capable (DCSC) and Channel Set Label + Extensions", RFC 6002, October 2010. + + [RFC6060] Fedyk, D., Shah, H., Bitar, N., and A. Takacs, + "Generalized Multiprotocol Label Switching (GMPLS) Control + of Ethernet Provider Backbone Traffic Engineering + (PBB-TE)", RFC 6060, March 2011. + + [RFC6205] Otani, T. and D. Li, "Generalized Labels for Lambda- + Switch-Capable (LSC) Label Switching Routers", RFC 6205, + March 2011. + + [RFC6387] Takacs, A., Berger, L., Caviglia, D., Fedyk, D., and J. + Meuric, "GMPLS Asymmetric Bandwidth Bidirectional Label + Switched Paths (LSPs)", RFC 6387, September 2011. + + [RFC6689] Berger, L., "Usage of the RSVP ASSOCIATION Object", + RFC 6689, July 2012. + + + + + + +Otani, et al. Informational [Page 10] + +RFC 7025 Reqs for GMPLS Apps of PCE September 2013 + + +6.2. Informative References + + [PCE-WSON-REQ] + Lee, Y., Bernstein, G., Martensson, J., Takeda, T., + Tsuritani, T., and O. Dios, "PCEP Requirements for WSON + Routing and Wavelength Assignment", Work in Progress, + June 2013. + + [PCEP-MIB] Koushik, K., Stephan, E., Zhao, Q., King, D., and J. + Hardwick, "PCE communication protocol (PCEP) Management + Information Base", Work in Progress, July 2013. + + [RFC4216] Zhang, R. and J. Vasseur, "MPLS Inter-Autonomous System + (AS) Traffic Engineering (TE) Requirements", RFC 4216, + November 2005. + + [RFC4655] Farrel, A., Vasseur, J., and J. Ash, "A Path Computation + Element (PCE)-Based Architecture", RFC 4655, August 2006. + + [RFC4657] Ash, J. and J. Le Roux, "Path Computation Element (PCE) + Communication Protocol Generic Requirements", RFC 4657, + September 2006. + + [RFC4726] Farrel, A., Vasseur, J., and A. Ayyangar, "A Framework for + Inter-Domain Multiprotocol Label Switching Traffic + Engineering", RFC 4726, November 2006. + + [RFC4874] Lee, CY., Farrel, A., and S. De Cnodder, "Exclude Routes - + Extension to Resource ReserVation Protocol-Traffic + Engineering (RSVP-TE)", RFC 4874, April 2007. + + [RFC5394] Bryskin, I., Papadimitriou, D., Berger, L., and J. Ash, + "Policy-Enabled Path Computation Framework", RFC 5394, + December 2008. + + [RFC5925] Touch, J., Mankin, A., and R. Bonica, "The TCP + Authentication Option", RFC 5925, June 2010. + + [RFC6457] Takeda, T. and A. Farrel, "PCC-PCE Communication and PCE + Discovery Requirements for Inter-Layer Traffic + Engineering", RFC 6457, December 2011. + + [RFC6952] Jethanandani, M., Patel, K., and L. Zheng, "Analysis of + BGP, LDP, PCEP, and MSDP Issues According to the Keying + and Authentication for Routing Protocols (KARP) Design + Guide", RFC 6952, May 2013. + + + + + +Otani, et al. Informational [Page 11] + +RFC 7025 Reqs for GMPLS Apps of PCE September 2013 + + +Authors' Addresses + + Tomohiro Otani + KDDI Corporation + 2-3-2 Nishi-shinjuku + Shinjuku-ku, Tokyo + Japan + Phone: +81-(3) 3347-6006 + EMail: tm-otani@kddi.com + + + Kenichi Ogaki + KDDI Corporation + 3-10-10 Iidabashi + Chiyoda-ku, Tokyo + Japan + Phone: +81-(3) 6678-0284 + EMail: ke-oogaki@kddi.com + + + 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 + Bantian, Longgang District, Shenzhen 518129 + P.R. China + Phone: +86-755-28972912 + EMail: zhangfatai@huawei.com + + + Cyril Margaria + Coriant R&D GmbH + St Martin Strasse 76 + Munich 81541 + Germany + Phone: +49 89 5159 16934 + EMail: cyril.margaria@coriant.com + + + + + + + +Otani, et al. Informational [Page 12] + |