PCE Working Group S. Sivabalan Internet-Draft C. Filsfils Intended status: Standards Track Cisco Systems, Inc. Expires: April 8, 2016 J. Tantsura Ericsson J. Hardwick Metaswitch Networks October 6, 2015 Conveying policies associated with traffic engineering paths over PCEP session draft-sivabalan-pce-policy-identifier-00.txt Abstract This document describes a simple extension to the Path Computation Element (PCE) Communication Protocol (PCEP) using which a PCEP speaker can enforce one or more policies on the other PCEP speaker. A policy is represented by a numeric value which can be interpreted only by the receiving PCEP speaker. Using the proposed extension, a path computation client (PCC) can signal one or more policies that must be taken into consideration by a PCE during path computation. Similarly, when initiating or updating a path, a stateful PCE can signal one or more policies (e.g., traffic steering rules) that a PCC is expected to apply to the path. 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." Sivabalan, et al. Expires April 8, 2016 [Page 1] Internet-Draft Path Policy ID October 2015 This Internet-Draft will expire on April 8, 2016. Copyright Notice Copyright (c) 2015 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. Motivation . . . . . . . . . . . . . . . . . . . . . . . . . 3 3. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 4 4. Policy Identifier TLV . . . . . . . . . . . . . . . . . . . . 4 5. Operation . . . . . . . . . . . . . . . . . . . . . . . . . . 5 6. Security Considerations . . . . . . . . . . . . . . . . . . . 5 7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 5 8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 5 9. Normative References . . . . . . . . . . . . . . . . . . . . 5 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 6 1. Introduction [RFC5440] describes the Path Computation Element Protocol (PCEP) for communication between a Path Computation Client (PCC) and a PCE or between a pair of PCEs. [I-D.ietf-pce-stateful-pce] specifies extension to PCEP that allows a PCC to delegate its LSPs to a PCE. The PCE can then update the state of LSPs delegated to it. [I-D.ietf-pce-pce-initiated-lsp] specifies a mechanism allowing a PCE to dynamically instantiate, maintain, and tear down Label Switched Paths (LSPs) without the need for configuring those LSPs on the PCC. Currently, the LSPs can either be signaled via RSVP-TE or can be segment routed as specified in [I-D.ietf-pce-segment-routing]. As described in the next section, a PCEP speaker may want to influence its PCEP counterpart with respect to path selection and other policies. This document describes a PCEP extension to signal policy identifier represented by numeric value using OPTIONAL PCEP Sivabalan, et al. Expires April 8, 2016 [Page 2] Internet-Draft Path Policy ID October 2015 TLV. The specification is applicable to both stateful and stateless PCEP sessions. 2. Motivation Paths computed using PCEP are subject to various policies on both PCE as well as PCC. For example, in a centralized traffic engineering scenario, network operators may instantiate LSPs and specifies policies for traffic steering, path monitoring, etc., for those LSPs via stateful PCE. Similarly, a PCC can request a path that is diverse from any other path originating from other PCC(s) from a stateful PCE. With a current state of PCEP, introducing such policy requires new PCEP extension. A generic mechanism that allows a PCEP speaker to specify the path policies without the need to know the details of such policies simplifies network operations, avoids frequent software upgrades, as well provides an ability to introduce new policy faster. Policy-ID Y Initiate & Monitor LSP {Disjoint paths} | | | PCReq | V {policy-ID Y} V +-----+ ----------------> +-----+ _ _ _ _ _ _| PCE | | | PCE | | +-----+ | ----------> +-----+ | PCEInitiate | | PCReq |{policy-ID X} | | {policy-ID Y} | | | | .-----. | | .-----. | ( ) | +----+ ( ) | .--( )--. | |PCC1|--.--( )--. V ( ) | +----+ ( ) +---+ ( ) | ( ) |PCC|----( MPLS network ) +----+ ( MPLS network ) +---+ ( ) |PCC2|------( ) Policy ID X ( ) +----+ ( ) {Monitor LSP} '--( )--' '--( )--' ( ) ( ) '-----' '-----' Case 1: Policy initiated by PCE Case 2: Policy initiated by PCC and enforced by PCC and enforced by PCE Figure 1: Sample use-cases for carrying policies over PCEP session Sivabalan, et al. Expires April 8, 2016 [Page 3] Internet-Draft Path Policy ID October 2015 3. Terminology The following terminologies are used in this document: LSP: Label Switched Path. PCC: Path Computation Client. PCE: Path Computation Element PCEP: Path Computation Element Protocol. TLV: Type, Length, and Value. 4. Policy Identifier TLV The new optional TLV is called "POLICY-ID-TLV" whose format is shown in the diagram below is defined to indicate the policies applied to a path. This TLV is associated with the RP or SRP objects specified in[RFC5440] and [I-D.ietf-pce-stateful-pce] respectively. The type of this TLV is to be allocated by IANA. 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 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Flags |M| Policy ID | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ ~ VENDOR-INFORMATION-TLV (optional) ~ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Figure 2: Format of POLICY-ID-TLV The TLV is formatted according to the rules specified in [RFC5440]. The body of the POLICY-ID-TLV contains one 1-Octet flags and 3-Octet policy identifier. By default, a policy is OPTIONAL. If the M-flag is set, the policy is considered MANDATORY. This TLV can optionally carry vendor-specific information via VENDOR-INFORMATION-TLV whose format and processing rules are specified in [RFC7470]. The presence of VENDOR-INFORMATION-TLV is detected based on the TLV length, and the content and processing rule of vendor-specific information is outside the scope of this specification. Sivabalan, et al. Expires April 8, 2016 [Page 4] Internet-Draft Path Policy ID October 2015 5. Operation A single message MAY contain more than one POLICY-ID-TLVs. In case, a a speaker receives a message containing multiple POLICY-ID-TLVs with the same policy ID, it MUST ignore all except for the first one itencounters in the message. If a PCEP speaker does not recognize the TLV, it MUST ignore the TLV in accordance with ([RFC5440]). If a PCEP speaker recognizes the TLV but does not support a mandatory policy included in the message, it MUST ignore the whole message and send PCErr with Error-Type = 2 (Capability not supported) as well include the POLICY-ID-TLV corresponding to the unsupported policies. When requesting a path from a PCE using a PCReq message ([RFC5440]), a PCC MAY include the POLICY-ID-TLV in the RP object. The PCE MUST take into account all the policies included in the PCReq otherwise it MUST ignore the whole message and send PCErr message as mentioned above. In the case of stateful PCE, POLICY-ID-TLV MAY be included in PCReq, PCRpt, PCUpd, and PCInitiate messages as well. When including POLICY-ID-TLV in PCRpt message, the SRP object MUST be present even in cases when the SRP-ID-number is the reserved value of 0x00000000. 6. Security Considerations No additional security measure is required. 7. IANA Considerations IANA is requested to allocate a new code point in the PCEP TLV Type Indicators registry, as follows: Value Description Reference TBD POLICY-ID-TLV This document 8. Acknowledgements 9. Normative References [I-D.ietf-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-ietf-pce-pce-initiated-lsp-04 (work in progress), April 2015. Sivabalan, et al. Expires April 8, 2016 [Page 5] Internet-Draft Path Policy ID October 2015 [I-D.ietf-pce-segment-routing] Sivabalan, S., Medved, J., Filsfils, C., Crabbe, E., Lopez, V., Tantsura, J., Henderickx, W., and J. Hardwick, "PCEP Extensions for Segment Routing", draft-ietf-pce- segment-routing-06 (work in progress), August 2015. [I-D.ietf-pce-stateful-pce] Crabbe, E., Minei, I., Medved, J., and R. Varga, "PCEP Extensions for Stateful PCE", draft-ietf-pce-stateful- pce-11 (work in progress), April 2015. [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/RFC2119, March 1997, . [RFC4206] Kompella, K. and Y. Rekhter, "Label Switched Paths (LSP) Hierarchy with Generalized Multi-Protocol Label Switching (GMPLS) Traffic Engineering (TE)", RFC 4206, DOI 10.17487/RFC4206, October 2005, . [RFC5440] Vasseur, JP., Ed. and JL. Le Roux, Ed., "Path Computation Element (PCE) Communication Protocol (PCEP)", RFC 5440, DOI 10.17487/RFC5440, March 2009, . [RFC5462] Andersson, L. and R. Asati, "Multiprotocol Label Switching (MPLS) Label Stack Entry: "EXP" Field Renamed to "Traffic Class" Field", RFC 5462, DOI 10.17487/RFC5462, February 2009, . [RFC7470] Zhang, F. and A. Farrel, "Conveying Vendor-Specific Constraints in the Path Computation Element Communication Protocol", RFC 7470, DOI 10.17487/RFC7470, March 2015, . Authors' Addresses Siva Sivabalan Cisco Systems, Inc. 2000 Innovation Drive Kanata, Ontario K2K 3E8 Canada Email: msiva@cisco.com Sivabalan, et al. Expires April 8, 2016 [Page 6] Internet-Draft Path Policy ID October 2015 Clarence Filsfils Cisco Systems, Inc. Pegasus Parc De kleetlaan 6a, DIEGEM BRABANT 1831 BELGIUM Email: cfilsfil@cisco.com Jeff Tantsura Ericsson 300 Holger Way San Jose, CA 95134 USA Email: jeff.tantsura@ericsson.com Jonathan Hardwick Metaswitch Networks 100 Church Street Enfield, Middlesex UK Email: Jonathan.Hardwick@metaswitch.com Sivabalan, et al. Expires April 8, 2016 [Page 7]