PCE Working Group S. Sivabalan Internet-Draft J. Medved Intended status: Standards Track Cisco Systems, Inc. Expires: April 07, 2014 I. Minei Juniper Networks, Inc. R. Varga Pantheon Technologies SRO E. Crabbe Google, Inc. October 04, 2013 LSP setup method in PCEP messages draft-sivabalan-pce-lsp-setup-type-00.txt Abstract A path computation element can compute traffic engineering paths (TE paths) through a network that are subject to various constraints. Currently, TE paths are label switched paths (LSPs) which are set up using the RSVP-TE signaling protocol. However, other TE path setup methods are possible within the PCE architecture. This document proposes an extension to PCEP to allow support for different LSP setup methods over a single PCEP session. 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 07, 2014. Sivabalan, et al. Expires April 07, 2014 [Page 1] Internet-Draft LSP setup method October 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. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3 3. LSP Setup Type TLV . . . . . . . . . . . . . . . . . . . . . 3 4. Operation . . . . . . . . . . . . . . . . . . . . . . . . . . 4 5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 5 6. Normative References . . . . . . . . . . . . . . . . . . . . 6 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 6 1. Introduction [RFC5440] describes the Path Computation Element Protocol (PCEP) for communication between a Path Computation Client (PCC) and a Path Control Element (PCE) or between one a pair of PCEs. A PCC requests from a PCE the computation of a path subject to various constraints and optimization criteria. The PCE responds to the PCC with a hop- by-hop path in an ER object. The PCC uses the ERO object to set up the path in the network. [I-D.ietf-pce-stateful-pce] specifies extensions to PCEP that allow a PCC to delegate its LSPs to the PCE. The PCE can then update the state of LSPs delegated to it. In particular, the PCE may modify the path of an LSP by sending a new ERO. The PCC uses this ERO to re- route the LSP in a make-before-break fashion. [I-D.crabbe-pce-pce-initiated-lsp] specifies a mechanism allowing a PCE to dynamically instantiate LSPs on a PCC by sending the path and characteristics of the LSP. The PCC signals the LSP using the ERO (and other attributes) sent by the PCE. So far, the PCEP protocol and its extensions implicitly assume that the TE paths are label-switched paths (LSPs), which are established via the RSVP-TE protocol. However, other methods of LSP setup are Sivabalan, et al. Expires April 07, 2014 [Page 2] Internet-Draft LSP setup method October 2013 not precluded. Most recently, Segment Routing has emerged as another technology for setting up source-routed TE paths. Other methods for setting up TE paths are possible in the future. [I-D.sivabalan-pce-segment-routing] specifies the ERO format for LSPs set up using SR (SR-ERO). However, it should be noted that when the LSP setup method over a given PCEP session is not the RSVP-TE signaling protocol, a new capability MUST be advertised when the PCEP session is established. A given PCEP session can be used to compute, initiate, and maintain LSPs which are set up using different setup methods. To facilitate this, the intended LSP setup method needs to be indicated in the appropriate PCEP messages, and the path of the LSP needs to be encoded in a format that is appropriate for the setup type. This document defines a new TLV called "LSP-SETUP-TYPE TLV" for this purpose. 2. Terminology The following terminologies are used in this document: ERO: Explicit Route Object. LSR: Label Switching Router. PCC: Path Computation Client. PCE: Path Computation Element PCEP: Path Computation Element Protocol. SR: Segment Routing. SR-ERO: Segment Routed Explicit Route Object. TLV: Type, Length, and Value. 3. LSP Setup Type TLV A PCC can simultaneously support setting up LSPs using different methods. To enable meaningful interaction with a PCE, the PCE must encode the LSP path in a format that is appropriate for the setup method used. To do so, the PCE must be made aware of the setup method used by the PCC for a particular LSP. 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 | Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | LSP-ST | Reserved | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Figure 1: LSP-SETUP-TYPE TLV LSP-SETUP-TYPE TLV is an optional TLV for use in the RP ([RFC5440]) and SRP ([I-D.ietf-pce-stateful-pce]) objects. Its format is shown Sivabalan, et al. Expires April 07, 2014 [Page 3] Internet-Draft LSP setup method October 2013 in the above figure. The type of the TLV is to be defined by IANA. The one octet value contains the LSP Setup Type (LSP-ST). This document specifies the following LSP-ST values: o ST = 0: LSP is setup via RSVP-TE signaling protocol(default). o ST = 1: LSP is setup via Segment Routing. In the absence of this TLV, RSVP-TE is assumed as the setup method. If an RP or SRP object contains more than one LSP-SETUP-TYPE TLV, only the first TLV MUST be processed and the rest MUST be ignored. 4. Operation When requesting the computation of a path from a PCE using a PCReq message ([RFC5440]), a PCC MAY include the LSP-SETUP-TYPE TLV in the RP object. If the PCE is capable of expressing the LSP path in a format appropriate for the setup method used, it MUST use the appropriate ERO format in the PCRep message. If the PCE does not support the intended LSP establishment type, but it does recognize the LSP-SETUP-TYPE TLV, it MUST send PCErr with Error-Type = TBD (LSP setup error) (recommended value is 19) and Error-Value = 1 (Unsupported LSP setup type,) and close the PCEP session. If an LSP setup type specified in PCRep message does not match that of the PCReq message, the PCC MUST send a PCErr with Error-Type = 19 (LSP setup error) and Error-Value = 2 (Mismatched LSP setup type) and close the PCEP session. In the case of stateful PCE, a PCC MUST report the setup type of all LSPs in PCRpt messages both in the synchronization phase and in subsequent updates. The absence of the LSP-SETUP-TYPE TLV is equivalent to an LSP_SETUP-TYPE TLV with an LSP-ST value of 0 (RSVP- TE), and it is recommended to omit including it when this is the case. If the LSP-SETUP-TYPE TLV needs to be included, the SRP object MUST be present even in cases when the SRP-ID-number is the reserved value of 0x00000000. A PCRpt message whose SRP-ID-number is not equal to 0x00000000 MUST match the path-type of the PCUpd message that triggered its generation. Otherwise, the PCE MUST send PCErr with Error-Type = 19 (LSP setup error) and Error-Value = 2 (Mismatched LSP setup type) and close the connection. In the case of PCE initiated LSPs, if a PCC does not support the path-type specified in PCInitiate message, the PCC MUST send PCErr with Error-Type = 19 (LSP setup error) and Error-Value = 1 (Unsupported LSP setup type) and close the PCEP session. The path- type in PCRpt messages generated as a result of a PCUpd or PCInitiate message MUST match the path-type of the message that triggered it. Otherwise, the PCE MUST send PCErr with Error-Type = 19 (LSP setup error) and Error-Value = 2 (Mismatched LSP setup type). For LSPs Sivabalan, et al. Expires April 07, 2014 [Page 4] Internet-Draft LSP setup method October 2013 that are not setup up using RSVP-TE signaling protocol, the path-type MUST be included in the SRP object, and the SRP object MUST be included even if the SRP-ID-number is the reserved value of 0x00000000. If a PCEP speaker does not support LSP-SETUP-TYPE TLV, it MUST send PCErr with Error-Type = 3 (Unknown Object) and Error-Value = 3 (Unsupported TLV). 5. IANA Considerations IANA is requested to allocate a new TLV type (recommended value is TBD)for LSP-SETUP-TYPE TLV specified in this document. This document requests that a registry is created to manage the value of the LSP Setup Type field in the LSP-SETUP-TYPE TLV. Value Description Reference 0 LSP is setup using RSVP signaling protocol This document 1 LSP is Segment Routed This document Table 1 This document also defines a new Error-Type (recommended 19) and new Error-Values for the following new error conditions: Error-Type Meaning 19 Invalid LSP setup type Error-value=1: Unsupported LSP setup type Error-value=2: Mismatched LSP setup type This document also defines a new Error-Value for the existing Error- Type 3 (Unknown Object): Error-Type Meaning 3 Unknown Object Error-value=3: Unsupported TLV Sivabalan, et al. Expires April 07, 2014 [Page 5] Internet-Draft LSP setup method October 2013 6. Normative References [I-D.crabbe-pce-pce-initiated-lsp] Crabbe, E., Minei, I., Sivabalan, S., and R. Varga, "PCEP Extensions for PCE-initiated LSP Setup in a Stateful PCE Model", draft-crabbe-pce-pce-initiated-lsp-02 (work in progress), July 2013. [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-06 (work in progress), August 2013. [I-D.sivabalan-pce-segment-routing] Sivabalan, S., Medved, J., Filsfils, C., Crabbe, E., and R. Raszuk, "PCEP Extensions for Segment Routing", draft- sivabalan-pce-segment-routing-01 (work in progress), July 2013. [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. [RFC5440] Vasseur, JP. and JL. Le Roux, "Path Computation Element (PCE) Communication Protocol (PCEP)", RFC 5440, March 2009. Authors' Addresses Siva Sivabalan Cisco Systems, Inc. 2000 Innovation Drive Kanata, Ontario K2K 3E8 Canada Email: msiva@cisco.com Jan Medved Cisco Systems, Inc. 170 West Tasman Dr. San Jose, CA 95134 USA Email: jmedved@cisco.com Sivabalan, et al. Expires April 07, 2014 [Page 6] Internet-Draft LSP setup method October 2013 Ina Minei Juniper Networks, Inc. 1194 N. Mathilda Ave. Sunnyvale, CA 94089 USA Email: ina@juniper.net Robert Varga Pantheon Technologies SRO Mlynske Nivy 56 Bratislava, 821 05 Slovakia Email: robert.vargad@pantheon.sk Edward Crabbe Google, Inc. 1600 Amphitheatre Parkway Mountain View, CA 94043 USA Email: edc@google.com Sivabalan, et al. Expires April 07, 2014 [Page 7]