Network Working Group E. Crabbe Internet-Draft Google, Inc. Intended status: Standards Track I. Minei Expires: January 13, 2014 Juniper Networks, Inc. S. Sivabalan Cisco Systems, Inc. R. Varga Pantheon Technologies SRO July 12, 2013 PCEP Extensions for PCE-initiated LSP Setup in a Stateful PCE Model draft-crabbe-pce-pce-initiated-lsp-02 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. The extensions described in [I-D.ietf-pce-stateful-pce] provide stateful control of Multiprotocol Label Switching (MPLS) Traffic Engineering Label Switched Paths (TE LSP) via PCEP, for a model where the PCC delegates control over one or more locally configured LSPs to the PCE. This document describes the creation and deletion of PCE- initiated LSPs under the stateful PCE model. 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." Crabbe, et al. Expires January 13, 2014 [Page 1] Internet-Draft Stateful PCE - PCE-initiated LSP July 2013 This Internet-Draft will expire on January 13, 2014. 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. Crabbe, et al. Expires January 13, 2014 [Page 2] Internet-Draft Stateful PCE - PCE-initiated LSP July 2013 Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 4 3. Architectural Overview . . . . . . . . . . . . . . . . . . . . 4 3.1. Motivation . . . . . . . . . . . . . . . . . . . . . . . . 4 3.2. Operation overview . . . . . . . . . . . . . . . . . . . . 5 4. Support of PCE-initiated LSPs . . . . . . . . . . . . . . . . 6 4.1. Stateful PCE Capability TLV . . . . . . . . . . . . . . . 6 5. PCE-initiated LSP instantiation and deletion . . . . . . . . . 7 5.1. The LSP Initiate Message . . . . . . . . . . . . . . . . . 7 5.2. The R flag in the SRP Object . . . . . . . . . . . . . . . 8 5.3. LSP instantiation . . . . . . . . . . . . . . . . . . . . 9 5.4. LSP deletion . . . . . . . . . . . . . . . . . . . . . . . 10 6. LSP delegation and cleanup . . . . . . . . . . . . . . . . . . 10 7. IANA considerations . . . . . . . . . . . . . . . . . . . . . 11 7.1. PCEP Messages . . . . . . . . . . . . . . . . . . . . . . 11 7.2. PCEP-Error Object . . . . . . . . . . . . . . . . . . . . 11 8. Security Considerations . . . . . . . . . . . . . . . . . . . 12 8.1. Malicious PCE . . . . . . . . . . . . . . . . . . . . . . 12 9. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 12 10. References . . . . . . . . . . . . . . . . . . . . . . . . . . 13 10.1. Normative References . . . . . . . . . . . . . . . . . . . 13 10.2. Informative References . . . . . . . . . . . . . . . . . . 14 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 14 Crabbe, et al. Expires January 13, 2014 [Page 3] Internet-Draft Stateful PCE - PCE-initiated LSP July 2013 1. Introduction [RFC5440] describes the Path Computation Element Protocol PCEP. PCEP defines the communication between a Path Computation Client (PCC) and a Path Control Element (PCE), or between PCE and PCE, enabling computation of Multiprotocol Label Switching (MPLS) for Traffic Engineering Label Switched Path (TE LSP) characteristics. Stateful pce [I-D.ietf-pce-stateful-pce] specifies a set of extensions to PCEP to enable stateful control of TE LSPs between and across PCEP sessions in compliance with [RFC4657]. It includes mechanisms to effect LSP state synchronization between PCCs and PCEs, delegation of control of LSPs to PCEs, and PCE control of timing and sequence of path computations within and across PCEP sessions and focuses on a model where LSPs are configured on the PCC and control over them is delegated to the PCE. This document describes the setup, maintenance and teardown of PCE- initiated LSPs under the stateful PCE model, without the need for local configuration on the PCC, thus allowing for a dynamic network that is centrally controlled and deployed. 2. Terminology This document uses the following terms defined in [RFC5440]: PCC, PCE, PCEP Peer. This document uses the following terms defined in [I-D.ietf-pce-stateful-pce]: Stateful PCE, Delegation, Redelegation Timeout, State Timeout Interval LSP State Report, LSP Update Request. The following terms are defined in this document: PCE-initiated LSP: LSP that is instantiated as a result of a request from the PCE. The message formats in this document are specified using Routing Backus-Naur Format (RBNF) encoding as specified in [RFC5511]. 3. Architectural Overview 3.1. Motivation [I-D.ietf-pce-stateful-pce] provides stateful control over LSPs that are locally configured on the PCC. This model relies on the LER taking an active role in delegating locally configured LSPs to the Crabbe, et al. Expires January 13, 2014 [Page 4] Internet-Draft Stateful PCE - PCE-initiated LSP July 2013 PCE, and is well suited in environments where the LSP placement is fairly static. However, in environments where the LSP placement needs to change in response to application demands, it is useful to support dynamic creation and tear down of LSPs. The ability for a PCE to trigger the creation of LSPs on demand can make possible agile software-driven network operation, and can be seamlessly integrated into a controller-based network architecture, where intelligence in the controller can determine when and where to set up paths. A possible use case is one of a software-driven network, where applications request network resources and paths from the network infrastructure. For example, an application can request a path with certain constraints between two LSRs by contacting the PCE. The PCE can compute a path satisfying the constraints, and instruct the head end LSR to instantiate and signal it. When the path is no longer required by the application, the PCE can request its teardown. Another use case is one of dynamically adjusting aggregate bandwidth between two points in the network using multiple LSPs. This functionality is very similar to auto-bandwidth, but allows for providing the desired capacity through multiple LSPs. This approach overcomes two of the limitations auto-bandwidth can experience: 1) growing the capacity between the endpoints beyond the capacity of individual links in the path and 2) achieving good bin-packing through use of several small LSPs instead of a single large one. The number of LSPs varies based on the demand, and LSPs are created and deleted dynamically to satisfy the bandwidth requirements. Another use case is that of demand engineering, where a PCE with visibility into both the network state and the demand matrix can anticipate and optimize how traffic is distributed across the infrastructure. Such optimizations may require creating new paths across the infrastructure. 3.2. Operation overview A PCC indicates its ability to support PCE provisioned dynamic LSPs during the PCEP Initialization Phase via a new flag in the STATEFUL- PCE-CAPABILITY TLV (see details in Section 4.1). The decision when to instantiate or delete a PCE-initiated LSP is out of the scope of this document. To instantiate or delete an LSP, the PCE sends a new message, the Path Computation LSP Initiate Request (PCInitiate) message to the PCC. The LSP Initiate Request MUST include the SRP and LSP objects, and the LSP object MUST include the Symbolic Path Name TLV. For an instantiation operation, the PCE MUST include the ERO and END- Crabbe, et al. Expires January 13, 2014 [Page 5] Internet-Draft Stateful PCE - PCE-initiated LSP July 2013 POINTS object and may include various attributes as per [RFC5440]. The PCC creates the LSP using the attributes communicated by the PCE, and local values for the unspecified parameters. It assigns a unique PLSP-ID for the LSP and automatically delegates the LSP to the PCE. It also generates an LSP State Report (PCRpt) for the LSP, carrying the newly assigned PLSP-ID and indicating the delegation via the delegation bit. The PCE may update the attributes of the LSP via subsequent PCUpd messages. Subsequent LSP State Report and LSP Update Request for the LSP will carry the PCC-assigned PLSP-ID, which uniquely identifies the LSP. See details in Section 5.3. Once instantiated, the delegation procedures for PCE-initiated LSPs are the same as for PCC initiated LSPs. This applies to the case of a PCE failure as well. In order to allow for network cleanup without manual intervention, the PCC SHOULD support removal of PCE-initiated LSPs as one of the behaviors applied on expiration of the State Timeout Interval [I-D.ietf-pce-stateful-pce]. The behavior SHOULD be picked based on local policy, and can result either in LSP removal, or into reverting to operator-defined default parameters. See details in Section 6. To indicate a delete operation, the PCE MUST use the R flag in the SRP object. As a result of the deletion request, the PCC MUST remove all state related to the LSP, and send a PCRpt with the R flag set for the removed state. See details in Section 5.3. 4. Support of PCE-initiated LSPs A PCC indicates its ability to support PCE provisioned dynamic LSPs during the PCEP Initialization phase. The Open Object in the Open message contains the "Stateful PCE Capability" TLV, defined in [I-D.ietf-pce-stateful-pce]. A new flag, the I (LSP-INSTANTIATION- CAPABILITY) flag is introduced to indicate support for instantiation of PCE-initiated LSPs. A PCE can initiate LSPs only for PCCs that advertised this capability and a PCC will follow the procedures described in this document only on sessions where the PCE advertised the I flag. 4.1. Stateful PCE Capability TLV The format of the STATEFUL-PCE-CAPABILITY TLV is shown in the following figure: Crabbe, et al. Expires January 13, 2014 [Page 6] Internet-Draft Stateful PCE - PCE-initiated LSP July 2013 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=16 | Length=4 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Flags |I|S|U| +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-++-+-+-+-+-+-+-+-+-+-++-+-+-+-+-+ Figure 1: STATEFUL-PCE-CAPABILITY TLV format The type of the TLV is defined in [I-D.ietf-pce-stateful-pce] and it has a fixed length of 4 octets. The value comprises a single field - Flags (32 bits). The U and S bits are defined in [I-D.ietf-pce-stateful-pce]. I (LSP-INSTANTIATION-CAPABILITY - 1 bit): If set to 1 by a PCC, the I Flag indicates that the PCC allows instantiation of an LSP by a PCE. If set to 1 by a PCE, the I flag indicates that the PCE will attempt to instantiate LSPs. The LSP-INSTANTIATION-CAPABILITY flag must be set by both PCC and PCE in order to support PCE- initiated LSP instantiation. Unassigned bits are considered reserved. They MUST be set to 0 on transmission and MUST be ignored on receipt. 5. PCE-initiated LSP instantiation and deletion To initiate an LSP, a PCE sends a PCInitiate message to a PCC. The message format, objects and TLVs are discussed separately below for the creation and the deletion cases. 5.1. The LSP Initiate Message A Path Computation LSP Initiate Message (also referred to as PCInitiate message) is a PCEP message sent by a PCE to a PCC to trigger LSP instantiation or deletion. The Message-Type field of the PCEP common header for the PCInitiate message is set to [TBD]. The PCInitiate message MUST include the SRP and the LSP objects, and may contain other objects, as discussed later in this section. If either the SRP or the LSP object is missing, the PCC MUST send a PCErr as described in [I-D.ietf-pce-stateful-pce]. LSP instantiation is done by sending an LSP Initiate Message with an LSP object with the reserved PLSP-ID 0. LSP deletion is done by sending an LSP Initiate Message with an LSP object carrying the PLSP-ID of the LSP to be removed and an SRP object with the R flag set (see Section 5.2). Crabbe, et al. Expires January 13, 2014 [Page 7] Internet-Draft Stateful PCE - PCE-initiated LSP July 2013 The format of a PCInitiate message for LSP instantiation is as follows: ::= Where: ::= [] ::= [] Where: is defined in [RFC5440] and extended by PCEP extensions. The SRP object is used to correlate between initiation requests sent by the PCE and the error reports and state reports sent by the PCC. Every request from the PCE receives a new SRP-ID-number. This number is unique per PCEP session and is incremented each time an operation (initiation, update, etc) is requested from the PCE. The value of the SRP-ID-number MUST be echoed back by the PCC in PCErr and PCRpt messages to allow for correlation between requests made by the PCE and errors or state reports generated by the PCC. Details of the SRP object and its use can be found in [I-D.ietf-pce-stateful-pce]. 5.2. The R flag in the SRP Object The format of the SRP object is shown Figure 2: 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 |R| +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | SRP-ID-number | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | | // Optional TLVs // | | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Figure 2: The SRP Object format Crabbe, et al. Expires January 13, 2014 [Page 8] Internet-Draft Stateful PCE - PCE-initiated LSP July 2013 The type object is defined in [I-D.ietf-pce-stateful-pce]. A new flag is defined to indicate a delete operation initiated by the PCE: R (LSP-REMOVE - 1 bit): If set to 1, it indicates a removal request initiated by the PCE. 5.3. LSP instantiation LSP instantiation is done by sending an LSP Initiate Message with an LSP object with the reserved PLSP-ID 0. Receipt of a PCInitiate Message with a non-zero PLSP-ID and the R flag in the SRP object set to zero results in a PCErr message of type 19 (Invalid Operation) and value 8 (non-zero PLSP-ID in LSP initiation request). The LSP-sig-type field in the LSP is set to the signaling type that is requested for the LSP setup. This draft defines procedures for RSVP-signaled LSPs. The END-POINTS Object is mandatory for an instantiation request of an RSVP-signaled LSP. It contains the source and destination addresses for provisioning the LSP. If the END-POINTS Object is missing, the PCC MUST send a PCErr message with Error-type=6 (Mandatory Object missing) and Error-value=3 (END-POINTS Object missing). The ERO Object is mandatory for an instantiation request. It contains the ERO for the LSP. If the ERO Object is missing, the PCC MUST send a PCErr message with Error-type=6 (Mandatory Object missing) and Error-value=9 (ERO Object missing). The LSP Object MUST include the SYMBOLIC-PATH-NAME TLV, which will be used to correlate between the PCC-assigned PLSP-ID and the LSP. If the TLV is missing, the PCC MUST send a PCErr message with Error- type=6(Mandatory object missing) and Error-value=14 (SYMBOLIC-PATH- NAME TLV missing). The symbolic name used for provisioning PCE- initiated LSPs must not have conflict with the LSP name of any existing LSP in the PCC. (Existing LSPs may be either statically configured, or initiated by another PCE). If there is conflict with the LSP name, the PCC MUST send a PCErr message with Error-type=23 (Bad Parameter value) and Error-value=1 (SYMBOLIC-PATH-NAME in use). The only exception to this rule is for LSPs for which the State timeout timer is running (see Section 6). The PCE MAY include various attributes as per [RFC5440]. The PCC MUST use these values in the LSP instantiation, and local values for Crabbe, et al. Expires January 13, 2014 [Page 9] Internet-Draft Stateful PCE - PCE-initiated LSP July 2013 unspecified parameters. After the LSP setup, the PCC MUST send a PCRpt to the PCE, reflecting these values. The SRP object in the PCRpt message MUST echo the value of the PCInitiate message that triggered the setup. If the PCC determines that the LSP parameters proposed in the PCInitiate message are unacceptable, it MUST trigger a PCErr with error-type=TBD (PCE instantiation error) and error-value=1 (Unacceptable instantiation parameters). If the PCC encounters an internal error during the processing of the PCInitiate message, it MUST trigger a PCErr with error-type=TBD (PCE instantiation error) and error-value=2 (Internal error). A PCC MUST relay to the PCE errors it encounters in the setup of PCE- initiated LSP by sending a PCErr with error-type=TBD (PCE instantiation error) and error-value=3 (RSVP signaling error). The PCErr MUST echo the SRP-id-number of the PCInitiate message. The PCEP-ERROR object SHOULD include the RSVP Error Spec TLV (if an ERROR SPEC was returned to the PCC by a downstream node). A PCC SHOULD be able to place a limit on either the number of LSPs or the percentage of resources that are allocated to honor PCE-initiated LSP requests. As soon as that limit is reached, the PCC MUST send a PCErr message of type 19 (Invalid Operation) and value TBD "PCE- initiated limit reached" and is free to drop any incoming PCInitiate messages without additional processing. 5.4. LSP deletion PCE-initiated removal of a PCE-initiated LSP is done by setting the R (remove) flag in the SRP Object in the PCInitiate message from the PCE. The LSP is identified by the PLSP-ID in the LSP object. If the PLSP-ID is unknown, the PCC MUST generate a PCErr with error type 19, error value 3, "Unknown PLSP-ID". A PLSP-ID of zero removes all LSPs that were initiated by the PCE. If the PLSP-ID specified in the PCInitiate message is not delegated to the PCE, the PCC MUST send a PCErr message indicating "LSP is not delegated" (Error code 19, error value 1 ([I-D.ietf-pce-stateful-pce]). Following the removal of the LSP, the PCC MUST send a PCRpt as described in [I-D.ietf-pce-stateful-pce]. 6. LSP delegation and cleanup PCE-initiated LSPs are automatically delegated by the PCC to the PCE upon instantiation. The PCC MUST delegate the LSP to the PCE by setting the delegation bit to 1 in the PCRpt that includes the assigned PLSP-ID. All subsequent messages from the PCC must have the Crabbe, et al. Expires January 13, 2014 [Page 10] Internet-Draft Stateful PCE - PCE-initiated LSP July 2013 delegation bit set to 1. The PCC cannot revoke the delegation for PCE-initiated LSPs for an active PCEP session. Sending a PCRpt message with the delegation bit set to 0 results in a PCErr message of type 19 (Invalid Operation) and value TBD "Delegation for PCE- initiated LSP cannot be revoked". A PCE MAY return a delegation to the PCC, to allow for LSP transfer between PCEs. Doing so MUST trigger the State Timeout Interval timer ([I-D.ietf-pce-stateful-pce]). In case of PCEP session failure, control over PCE-initiated LSPs reverts to the PCC at the expiration of the redelegation timeout. To obtain control of a PCE-initiated LSP, a PCE (either the original or one of its backups) sends a PCInitiate message, including just the SRP and LSP objects, and carrying the PLSP-ID of the LSP it wants to take control of. Receipt of a PCInitiate message with a non-zero PLSP-ID normally results in the generation of a PCErr. If the State Timeout timer is running, the PCC MUST NOT generate an error and redelegate the LSP to the PCE. The State Timeout timer is stopped upon the redelegation. The State Timeout timer ensures that a PCE crash does not result in automatic and immediate disruption for the services using PCE- initiated LSPs. PCE-initiated LSPs are not be removed immediately upon PCE failure. Instead, they are cleaned up on the expiration of this timer. This allows for network cleanup without manual intervention. The PCC SHOULD support removal of PCE-initiated LSPs as one of the behaviors applied on expiration of the State Timeout Interval [I-D.ietf-pce-stateful-pce]. The behavior SHOULD be picked based on local policy, and can result either in LSP removal, or into reverting to operator-defined default parameters. 7. IANA considerations 7.1. PCEP Messages This document defines the following new PCEP messages: Value Meaning Reference 12 Initiate This document 7.2. PCEP-Error Object This document defines new Error-Type and Error-Value for the following new error conditions: Crabbe, et al. Expires January 13, 2014 [Page 11] Internet-Draft Stateful PCE - PCE-initiated LSP July 2013 Error-Type Meaning 6 Mandatory Object missing Error-value=13: LSP cleanup TLV missing Error-value=14: SYMBOLIC-PATH-NAME TLV missing 19 Invalid operation Error-value=6: PCE-initiated LSP limit reached Error-value=7: Delegation for PCE-initiated LSP cannot be revoked Error-value=8: Non-zero PLSP-ID in LSP initiation request 23 Bad parameter value Error-value=1: SYMBOLIC-PATH-NAME in use 24 LSP instantiation error Error-value=1: Unacceptable instantiation parameters Error-value=2: Internal error Error-value=3: RSVP signaling error 8. Security Considerations The security considerations described in [I-D.ietf-pce-stateful-pce] apply to the extensions described in this document. Additional considerations related to a malicious PCE are introduced. 8.1. Malicious PCE The LSP instantiation mechanism described in this document allows a PCE to generate state on the PCC and throughout the network. As a result, it introduces a new attack vector: an attacker may flood the PCC with LSP instantiation requests and consume network and LSR resources, either by spoofing messages or by compromising the PCE itself. A PCC can protect itself from such an attack by imposing a limit on either the number of LSPs or the percentage of resources that are allocated to honor PCE-initiated LSP requests. As soon as that limit is reached, the PCC MUST send a PCErr message of type 19 (Invalid Operation) and value 3 "PCE-initiated LSP limit reached" and is free to drop any incoming PCInitiate messages without additional processing. Rapid flaps triggered by the PCE can also be an attack vector. This will be discussed in a future version of this document. 9. Acknowledgements We would like to thank Jan Medved, Ambrose Kwong and Raveendra Trovi Crabbe, et al. Expires January 13, 2014 [Page 12] Internet-Draft Stateful PCE - PCE-initiated LSP July 2013 for their contributions to this document. 10. References 10.1. 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-05 (work in progress), July 2013. [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. [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. Crabbe, et al. Expires January 13, 2014 [Page 13] Internet-Draft Stateful PCE - PCE-initiated LSP July 2013 10.2. 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, "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 Crabbe, et al. Expires January 13, 2014 [Page 14] Internet-Draft Stateful PCE - PCE-initiated LSP July 2013 Ina Minei Juniper Networks, Inc. 1194 N. Mathilda Ave. Sunnyvale, CA 94089 US Email: ina@juniper.net Siva Sivabalan Cisco Systems, Inc. 170 West Tasman Dr. San Jose, CA 95134 US Email: msiva@cisco.com Robert Varga Pantheon Technologies SRO Mlynske Nivy 56 Bratislava 821 05 Slovakia Email: robert.varga@pantheon.sk Crabbe, et al. Expires January 13, 2014 [Page 15]