Network Working Group E. Crabbe Internet-Draft Google, Inc. Intended status: Standards Track J. Medved Expires: April 18, 2013 Cisco Systems, Inc. I. Minei Juniper Networks, Inc. R. Varga Pantheon Technologies SRO October 15, 2012 Stateful PCE extensions for MPLS-TE LSPs draft-crabbe-pce-stateful-pce-mpls-te-00 Abstract The Path Computation Element Communication Protocol (PCEP) provides mechanisms for Path Computation Elements (PCEs) to perform path computations in response to Path Computation Clients (PCCs) requests. [I-D.ietf-pce-stateful-pce] describes a set of extensions to PCEP to provide stateful control. This document describes the objects and TLVs to be used with these PCEP extensions to control Multiprotocol Label Switching (MPLS) Traffic Engineering Label Switched Paths (TE LSP) via a stateful PCE. 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]. Status of this Memo This Internet-Draft is submitted in full conformance with the provisions of BCP 78 and BCP 79. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF). Note that other groups may also distribute working documents as Internet-Drafts. The list of current Internet- Drafts is at http://datatracker.ietf.org/drafts/current/. 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." This Internet-Draft will expire on April 18, 2013. Crabbe, et al. Expires April 18, 2013 [Page 1] Internet-Draft Stateful PCE extensions for MPLS-TE LSPs October 2012 Copyright Notice Copyright (c) 2012 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 . . . . . . . . . . . . . . . . . . . . . . . . . 3 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3 3. Motivation . . . . . . . . . . . . . . . . . . . . . . . . . . 3 4. MPLS-TE specific descriptors used in PCEP Messages . . . . . . 3 4.1. MPLS-TE specific descriptors for the PCRpt Message . . . . 4 4.2. MPLS-TE specific descriptors for the PCUpd Message . . . . 4 4.3. MPLS-TE specific encoding for the PCReq Message for stateful PCE . . . . . . . . . . . . . . . . . . . . . . . 6 4.4. MPLS-TE specific encoding for the PCRep Message for stateful PCE . . . . . . . . . . . . . . . . . . . . . . . 7 5. Object and TLV Formats . . . . . . . . . . . . . . . . . . . . 8 5.1. LSP Identifiers TLVs . . . . . . . . . . . . . . . . . . . 8 5.2. Tunnel ID TLV . . . . . . . . . . . . . . . . . . . . . . 11 5.3. LSP Update Error Code TLV . . . . . . . . . . . . . . . . 11 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 12 6.1. PCEP Objects . . . . . . . . . . . . . . . . . . . . . . . 12 6.2. PCEP-Error Object . . . . . . . . . . . . . . . . . . . . 12 6.3. PCEP TLV Type Indicators . . . . . . . . . . . . . . . . . 12 7. Security Considerations . . . . . . . . . . . . . . . . . . . 13 8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 13 9. References . . . . . . . . . . . . . . . . . . . . . . . . . . 13 9.1. Normative References . . . . . . . . . . . . . . . . . . . 13 9.2. Informative References . . . . . . . . . . . . . . . . . . 14 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 15 Crabbe, et al. Expires April 18, 2013 [Page 2] Internet-Draft Stateful PCE extensions for MPLS-TE LSPs October 2012 1. Introduction The Path Computation Element Communication Protocol (PCEP) provides mechanisms for Path Computation Elements (PCEs) to perform path computations in response to Path Computation Clients (PCCs) requests. [I-D.ietf-pce-stateful-pce] describes a set of extensions to PCEP to provide stateful control. This document describes the objects and TLVs to be used with these PCEP extensions to control Multiprotocol Label Switching (MPLS) Traffic Engineering Label Switched Paths (TE LSP) via a stateful PCE. 2. Terminology This document uses the following terms defined in [RFC5440]: PCC, PCE, PCEP Peer. This document uses the following terms defined in [RFC4090]: MPLS TE Fast Reroute (FRR), FRR One-to-One Backup, FRR Facility Backup. This document uses the following terms defined in [I-D.ietf-pce-stateful-pce] : Passive Stateful PCE, Active Stateful PCE, Delegation, Delegation Timeout Interval, LSP State Report, LSP Update Request, LSP Priority, LSP State Database, Revocation. Within this document, when describing PCE-PCE communications, the requesting PCE fills the role of a PCC. This provides a saving in documentation without loss of function. The message formats in this document are specified using Routing Backus-Naur Format (RBNF) encoding as specified in [RFC5511]. 3. Motivation Several use cases for stateful PCE in an MPLS-TE network are included in [I-D.ietf-pce-stateful-pce]. 4. MPLS-TE specific descriptors used in PCEP Messages As defined in [RFC5440], a PCEP message consists of a common header followed by a variable-length body made of a set of objects that can be either mandatory or optional. [I-D.ietf-pce-stateful-pce] describes the messages and objects needed in support of stateful PCE. The following sections contain MPLS-TE specific descriptors used in some of these messages. Crabbe, et al. Expires April 18, 2013 [Page 3] Internet-Draft Stateful PCE extensions for MPLS-TE LSPs October 2012 4.1. MPLS-TE specific descriptors for the PCRpt Message The format of the PCRpt message is defined in [I-D.ietf-pce-stateful-pce] as follows, and included here for easy reference: ::= Where: ::= [] ::= [] Where: ::=[] For MPLS-TE LSPs, the path descriptor is defined as follows: ::= Where: ::= [] [] [] [] ::= [] The LSP State Report MAY contain a path descriptor for the primary path and one or more path descriptors for backup paths. A path descriptor MUST contain an ERO object as it was specified by a PCE or an operator. A path descriptor MUST contain the RRO object if a primary or secondary LSP is set up along the path in the network. A path descriptor MAY contain the LSPA, BANDWIDTH, and METRIC objects. The ERO,LSPA, BANDWIDTH, METRIC, and RRO objects are defined in[RFC5440]. 4.2. MPLS-TE specific descriptors for the PCUpd Message A Path Computation LSP Update Request message (also referred to as PCUpd message) is a PCEP message sent by a PCE to a PCC to update attributes of an LSP. A PCUpd message can carry more than one LSP Update Request. The Message-Type field of the PCEP common header for the PCUpd message is set to [TBD]. Crabbe, et al. Expires April 18, 2013 [Page 4] Internet-Draft Stateful PCE extensions for MPLS-TE LSPs October 2012 The format of the PCUpd message is defined in [I-D.ietf-pce-stateful-pce] and included here for easy reference: ::= Where: ::= [] ::= [] Where: ::=[] For MPLS-TE LSPs, the endoding of path descriptor is defined as follows: ::= Where: ::= Where: ::= [] [] [] ::= [] There is one mandatory object that MUST be included within each LSP Update Request in the PCUpd message: the LSP object (see [I-D.ietf-pce-stateful-pce]). If the LSP object is missing, the receiving PCE MUST send a PCErr message with Error-type=6 (Mandatory Object missing) and Error-value=[TBD] (LSP object missing). The LSP Update Request MUST contain a path descriptor for the primary path, and MAY contain one or more path descriptors for backup paths. A path descriptor MUST contain an ERO object. A path descriptor MAY further contain the BANDWIDTH, IRO, and METRIC objects. The ERO, LSPA, BANDWIDTH, METRIC, and IRO objects are defined in [RFC5440]. Each LSP Update Request results in a separate LSP setup operation at a PCC. An LSP Update Request MUST contain all LSP parameters that a PCC wishes to set for the LSP. A PCC MAY set missing parameters from Crabbe, et al. Expires April 18, 2013 [Page 5] Internet-Draft Stateful PCE extensions for MPLS-TE LSPs October 2012 locally configured defaults. If the LSP specified the Update Request is already up, it will be re-signaled. The PCC will use make-before- break whenever possible in the re-signaling operation. A PCC MUST respond with an LSP State Report to each LSP Update Request to indicate the resulting state of the LSP in the network. A PCC MAY respond with multiple LSP State Reports to report LSP setup progress of a single LSP. If the rate of PCUpd messages sent to a PCC for the same target LSP exceeds the rate at which the PCC can signal LSPs into the network, the PCC MAY perform state compression and only re-signal the last modification in its queue. Note that a PCC MUST process all LSP Update Requests - for example, an LSP Update Request is sent when a PCE returns delegation or puts an LSP into non-operational state. The protocol relies on TCP for message-level flow control. Note also that it's up to the PCE to handle inter-LSP dependencies; for example, if ordering of LSP set-ups is required, the PCE has to wait for an LSP State Report for a previous LSP before triggering the LSP setup of a next LSP. 4.3. MPLS-TE specific encoding for the PCReq Message for stateful PCE A PCC MAY include the LSP object defined in [I-D.ietf-pce-stateful-pce] in the PCReq message if the stateful PCE capability has been negotiated on a PCEP session between the PCC and a PCE. The definition of the PCReq message (see [RFC5440], Section 6.4) is then extended as follows: Crabbe, et al. Expires April 18, 2013 [Page 6] Internet-Draft Stateful PCE extensions for MPLS-TE LSPs October 2012 ::= [] Where: ::=[] ::=[] ::= [] <--- New Object [] [] [] [[]] [] [] Where: ::=[] 4.4. MPLS-TE specific encoding for the PCRep Message for stateful PCE A PCE MAY include the LSP object defined in [I-D.ietf-pce-stateful-pce] in the PCRep message if the stateful PCE capability has been negotiated on a PCEP session between the PCC and the PCE and the LSP object was included in the corresponding PCReq message from the PCC. The definition of the PCRep message (see [RFC5440], Section 6.5) is then extended as follows Crabbe, et al. Expires April 18, 2013 [Page 7] Internet-Draft Stateful PCE extensions for MPLS-TE LSPs October 2012 ::= Where: ::=[] ::= [] <--- New Object [] [] [] ::=[] ::= Where: ::=[] [] [] [] ::=[] 5. Object and TLV Formats The PCEP objects defined in this document are compliant with the PCEP object format defined in [RFC5440]. The P flag and the I flag of the PCEP objects defined in this document MUST always be set to 0 on transmission and MUST be ignored on receipt since these flags are exclusively related to path computation requests. 5.1. LSP Identifiers TLVs Whenever the value of an LSP identifier changes, a PCC MUST send out an LSP State Report, where the LSP Object carries the LSP Identifiers TLV that contains the new value. The LSP Identifiers TLV MUST also be included in the LSP object during state synchronization. There are two LSP Identifiers TLVs, one for IPv4 and one for IPv6. The format of the IPV4-LSP-IDENTIFIERS TLV is shown in the following figure: Crabbe, et al. Expires April 18, 2013 [Page 8] Internet-Draft Stateful PCE extensions for MPLS-TE LSPs October 2012 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=[TBD] | Length=12 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | IPv4 Tunnel Sender Address | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | LSP ID | Tunnel ID | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Extended Tunnel ID | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Figure 1: IPV4-LSP-IDENTIFIERS TLV format The type of the TLV is [TBD] and it has a fixed length of 12 octets. The value contains the following fields: IPv4 Tunnel Sender Address: contains the sender node's IPv4 address, as defined in [RFC3209], Section 4.6.2.1 for the LSP_TUNNEL_IPv4 Sender Template Object. LSP ID: contains the 16-bit 'LSP ID' identifier defined in [RFC3209], Section 4.6.2.1 for the LSP_TUNNEL_IPv4 Sender Template Object. Tunnel ID: contains the 16-bit 'Tunnel ID' identifier defined in [RFC3209], Section 4.6.1.1 for the LSP_TUNNEL_IPv4 Session Object. Tunnel ID remains constant over the life time of a tunnel. However, when Global Path Protection or Global Default Restoration is used, both the primary and secondary LSPs have their own Tunnel IDs. A PCC will report a change in Tunnel ID when traffic switches over from primary LSP to secondary LSP (or vice versa). Extended Tunnel ID: contains the 32-bit 'Extended Tunnel ID' identifier defined in [RFC3209], Section 4.6.1.1 for the LSP_TUNNEL_IPv4 Session Object. The format of the IPV6-LSP-IDENTIFIERS TLV is shown in l following figure: Crabbe, et al. Expires April 18, 2013 [Page 9] Internet-Draft Stateful PCE extensions for MPLS-TE LSPs October 2012 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=[TBD] | Length=36 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | | + + | IPv6 tunnel sender address | + (16 octets) + | | + + | | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | LSP ID | Tunnel ID | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | | + + | Extended Tunnel ID | + (16 octets) + | | + + | | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Figure 2: IPV6-LSP-IDENTIFIERS TLV format The type of the TLV is [TBD] and it has a fixed length of 36 octets. The value contains the following fields: IPv6 Tunnel Sender Address: contains the sender node's IPv6 address, as defined in [RFC3209], Section 4.6.2.2 for the LSP_TUNNEL_IPv6 Sender Template Object. LSP ID: contains the 16-bit 'LSP ID' identifier defined in [RFC3209], Section 4.6.2.2 for the LSP_TUNNEL_IPv6 Sender Template Object. Tunnel ID: contains the 16-bit 'Tunnel ID' identifier defined in [RFC3209], Section 4.6.1.2 for the LSP_TUNNEL_IPv6 Session Object. Tunnel ID remains constant over the life time of a tunnel. However, when Global Path Protection or Global Default Restoration is used, both the primary and secondary LSPs have their own Tunnel IDs. A PCC will report a change in Tunnel ID when traffic switches over from primary LSP to secondary LSP (or vice versa). Crabbe, et al. Expires April 18, 2013 [Page 10] Internet-Draft Stateful PCE extensions for MPLS-TE LSPs October 2012 Extended Tunnel ID: contains the 128-bit 'Extended Tunnel ID' identifier defined in [RFC3209], Section 4.6.1.2 for the LSP_TUNNEL_IPv6 Session Object. 5.2. Tunnel ID TLV The Tunnel ID TLV MAY be included in the LSPA object. The format of the TUNNEL TLV is shown in the following figure: 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=[TBD] | Length=4 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Reserved | Tunnel ID | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Figure 3: Tunnel-ID TLV format The type of the TLV is [TBD] and it has a fixed length of 4 octets. The value contains a single field: Tunnel ID: contains the 16-bit 'Tunnel ID' identifier defined in [RFC3209], Section 4.6.1.1 for the LSP_TUNNEL_IPv4 Session Object. Tunnel ID remains constant over the life time of a tunnel. However, when Global Path Protection or Global Default Restoration is used, both the primary and secondary LSPs have their own Tunnel IDs. 5.3. LSP Update Error Code TLV If an LSP Update Request failed, an LSP State Report MUST be sent to all connected stateful PCEs. LSP State Report MUST contain the LSP Update Error Code TLV, indicating the cause of the failure. The format of the LSP-UPDATE-ERROR-CODE TLV is shown in the following figure: 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=[TBD] | Length=4 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Error Code | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Crabbe, et al. Expires April 18, 2013 [Page 11] Internet-Draft Stateful PCE extensions for MPLS-TE LSPs October 2012 Figure 4: LSP-UPDATE-ERROR-CODE TLV format The type of the TLV is [TBD] and it has a fixed length of 4 octets. The value contains the error code that indicates the cause of the LSP setup failure. Error codes will be defined in a later revision of this document. 6. IANA Considerations This document requests IANA actions to allocate code points for the protocol elements defined in this document. Values shown here are suggested for use by IANA. 6.1. PCEP Objects This document defines the following new PCEP Object-classes and Object-values: Object-Class Value Name Reference 32 LSP This document Object-Type 1 6.2. PCEP-Error Object This document defines new Error-Type and Error-Value for the following new error conditions: Error-Type Meaning 6 Mandatory Object missing Error-value=9: ERO Object missing for a path in an LSP Update Request where TE-LSP setup is requested Error-value=10: BANDWIDTH Object missing for a path in an LSP Update Request where TE-LSP setup is requested Error-value=11: LSPA Object missing for a path in an LSP Update Request where TE-LSP setup is requested 6.3. PCEP TLV Type Indicators This document defines the following new PCEP TLVs: Crabbe, et al. Expires April 18, 2013 [Page 12] Internet-Draft Stateful PCE extensions for MPLS-TE LSPs October 2012 Value Meaning Reference 18 IPV4-LSP-IDENTIFIERS This document 19 IPV6-LSP-IDENTIFIERS This document 20 LSP-UPDATE-ERROR-CODE This document 24 TUNNEL-ID This document 7. Security Considerations The security considerations listed in [I-D.ietf-pce-stateful-pce] apply to this document as well. 8. Acknowledgements We would like to thank Adrian Farrel, Cyril Margaria and Ramon Casellas for their contributions to this document. We would like to thank Shane Amante,Julien Meuric, Kohei Shiomoto, Paul Schultz and Raveendra Torvi for their comments and suggestions. Thanks also to Dhruv Dhoddy, Oscar Gonzales de Dios, Tomas Janciga, Stefan Kobza and Kexin Tang for helpful discussions. 9. References 9.1. Normative References [I-D.ietf-pce-stateful-pce] Crabbe, E., Medved, J., Minei, I., and R. Varga, "PCEP Extensions for Stateful PCE", draft-ietf-pce-stateful-pce-02 (work in progress), October 2012. [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. [RFC2205] Braden, B., Zhang, L., Berson, S., Herzog, S., and S. Jamin, "Resource ReSerVation Protocol (RSVP) -- Version 1 Functional Specification", RFC 2205, September 1997. [RFC3209] Awduche, D., Berger, L., Gan, D., Li, T., Srinivasan, V., and G. Swallow, "RSVP-TE: Extensions to RSVP for LSP Tunnels", RFC 3209, December 2001. [RFC4090] Pan, P., Swallow, G., and A. Atlas, "Fast Reroute Extensions to RSVP-TE for LSP Tunnels", RFC 4090, May 2005. Crabbe, et al. Expires April 18, 2013 [Page 13] Internet-Draft Stateful PCE extensions for MPLS-TE LSPs October 2012 [RFC5088] Le Roux, JL., Vasseur, JP., Ikejiri, Y., and R. Zhang, "OSPF Protocol Extensions for Path Computation Element (PCE) Discovery", RFC 5088, January 2008. [RFC5089] Le Roux, JL., Vasseur, JP., Ikejiri, Y., and R. Zhang, "IS-IS Protocol Extensions for Path Computation Element (PCE) Discovery", RFC 5089, January 2008. [RFC5226] Narten, T. and H. Alvestrand, "Guidelines for Writing an IANA Considerations Section in RFCs", BCP 26, RFC 5226, May 2008. [RFC5440] Vasseur, JP. and JL. Le Roux, "Path Computation Element (PCE) Communication Protocol (PCEP)", RFC 5440, March 2009. [RFC5511] Farrel, A., "Routing Backus-Naur Form (RBNF): A Syntax Used to Form Encoding Rules in Various Routing Protocol Specifications", RFC 5511, April 2009. 9.2. Informative References [RFC2702] Awduche, D., Malcolm, J., Agogbua, J., O'Dell, M., and J. McManus, "Requirements for Traffic Engineering Over MPLS", RFC 2702, September 1999. [RFC3031] Rosen, E., Viswanathan, A., and R. Callon, "Multiprotocol Label Switching Architecture", RFC 3031, January 2001. [RFC3346] Boyle, J., Gill, V., Hannan, A., Cooper, D., Awduche, D., Christian, B., and W. Lai, "Applicability Statement for Traffic Engineering with MPLS", RFC 3346, August 2002. [RFC3630] Katz, D., Kompella, K., and D. Yeung, "Traffic Engineering (TE) Extensions to OSPF Version 2", RFC 3630, September 2003. [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. [RFC5305] Li, T. and H. Smit, "IS-IS Extensions for Traffic Engineering", RFC 5305, October 2008. [RFC5394] Bryskin, I., Papadimitriou, D., Berger, L., and J. Ash, Crabbe, et al. Expires April 18, 2013 [Page 14] Internet-Draft Stateful PCE extensions for MPLS-TE LSPs October 2012 "Policy-Enabled Path Computation Framework", RFC 5394, December 2008. [RFC5557] Lee, Y., Le Roux, JL., King, D., and E. Oki, "Path Computation Element Communication Protocol (PCEP) Requirements and Protocol Extensions in Support of Global Concurrent Optimization", RFC 5557, July 2009. Authors' Addresses Edward Crabbe Google, Inc. 1600 Amphitheatre Parkway Mountain View, CA 94043 US Email: edc@google.com Jan Medved Cisco Systems, Inc. 170 West Tasman Dr. San Jose, CA 95134 US Email: jmedved@cisco.com Ina Minei Juniper Networks, Inc. 1194 N. Mathilda Ave. Sunnyvale, CA 94089 US Email: ina@juniper.net Robert Varga Pantheon Technologies SRO Mlynske Nivy 56 Bratislava 821 05 Slovakia Email: robert.varga@pantheon.sk Crabbe, et al. Expires April 18, 2013 [Page 15]