PCE Working Group D. Dhody Internet-Draft F. Zhang Intended status: Standards Track X. Zhang Expires: April 11, 2014 Huawei Technologies October 08, 2013 PCEP Extensions for Receiving SRLG Information draft-dhody-pce-srlg-collection-00 Abstract The Path Computation Element (PCE) provides functions of path computation in support of traffic engineering in networks controlled by Multi-Protocol Label Switching (MPLS) and Generalized MPLS (GMPLS). This document provides extensions for the Path Computation Element Protocol (PCEP) to support collection of Shared Risk Link Group (SRLG) information during path computation and encoding this information in the reply message. 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 11, 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 Dhody, et al. Expires April 11, 2014 [Page 1] Internet-Draft PCE-SRLG October 2013 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 1.1. Requirements Language . . . . . . . . . . . . . . . . . . 3 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3 3. PCEP Requirements . . . . . . . . . . . . . . . . . . . . . . 3 4. Extension to PCEP . . . . . . . . . . . . . . . . . . . . . . 4 4.1. The Extension of the RP Object . . . . . . . . . . . . . 4 4.2. SRLG Subobject in ERO . . . . . . . . . . . . . . . . . . 4 5. Other Considerations . . . . . . . . . . . . . . . . . . . . 5 5.1. Backward Compatibility . . . . . . . . . . . . . . . . . 5 5.2. Confidentiality via PathKey . . . . . . . . . . . . . . . 5 6. Security Considerations . . . . . . . . . . . . . . . . . . . 5 7. Manageability Considerations . . . . . . . . . . . . . . . . 5 7.1. Control of Function and Policy . . . . . . . . . . . . . 5 7.2. Information and Data Models . . . . . . . . . . . . . . . 5 7.3. Liveness Detection and Monitoring . . . . . . . . . . . . 5 7.4. Verify Correct Operations . . . . . . . . . . . . . . . . 6 7.5. Requirements On Other Protocols . . . . . . . . . . . . . 6 7.6. Impact On Network Operations . . . . . . . . . . . . . . 6 8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 6 8.1. New Subobjects for the ERO Object . . . . . . . . . . . . 6 9. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 6 10. References . . . . . . . . . . . . . . . . . . . . . . . . . 6 10.1. Normative References . . . . . . . . . . . . . . . . . . 6 10.2. Informative References . . . . . . . . . . . . . . . . . 6 Appendix A. Contributor Addresses . . . . . . . . . . . . . . . 8 1. Introduction As per [RFC4655], PCE based path computation model is deployed in large, multi-domain, multi-region, or multi-layer networks. In such case PCEs may cooperate with each other to provide end to end optimal path. It is important to understand which TE links in the network might be at risk from the same failures. In this sense, a set of links may constitute a 'shared risk link group' (SRLG) if they share a resource whose failure may affect all links in the set [RFC4202]. H-LSP (Hierarchical LSP) or S-LSP (Stitched LSP) can be used for carrying one or more other LSPs as described in [RFC4206] and [RFC6107]. H-LSP and S-LSP may be computed by PCE(s) and further form as a TE Dhody, et al. Expires April 11, 2014 [Page 2] Internet-Draft PCE-SRLG October 2013 link. The SRLG information of such LSPs can be collected during path computation itself and encoded in the PCEP Path Computation Reply (PCRep) message. [I-D.zhang-ccamp-gmpls-uni-app] describes the use of PCE for end to end User-Network Interface (UNI) path computation. [I-D.farrel-interconnected-te-info-exchange] describes a scaling problem with SRLGs in multi-layer environment and introduce a concept of Macro SRLG. Lower layer SRLG collection at the time of path computation can be used to generate such a Macro SRLG at the PCE. Note that [I-D.ietf-ccamp-rsvp-te-srlg-collect] specifies a similar extension to Resource ReserVation Protocol-Traffic Engineering (RSVP- TE) where SRLG information is collected at the time of signaling. 1.1. 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]. 2. Terminology The following terminology is used in this document. CPS: Confidential Path Segment. A segment of a path that contains nodes and links that the policy requires not to be disclosed outside the domain. PCE: Path Computation Element. An entity (component, application, or network node) that is capable of computing a network path or route based on a network graph and applying computational constraints. SRLG: Shared Risk Link Group. UNI: User-Network Interface. 3. PCEP Requirements Following key requirements are identified for PCEP to enable SRLG information collection during path computation: SRLG Collection Indication: The PCEP speaker must be capable of indicating whether the SRLG information of the LSP should be collected during the path computation procedure. Dhody, et al. Expires April 11, 2014 [Page 3] Internet-Draft PCE-SRLG October 2013 SRLG Collection: If requested, the SRLG information should be collected during the path computation and encoded in the PCRep message. 4. Extension to PCEP This document extends the existing RP (Request Parameters) object [RFC5440] so that a PCEP speaker can request SRLG information collection during path computation. The SRLG subobject maybe carried inside the Explicit Route Object (ERO) in the PCRep message. 4.1. The Extension of the RP Object This document adds the following flags to the RP Object: S (SRLG - 1 bit): when set, in a PCReq message, this indicates that the SRLG information of the Label switched path (LSP) should be collected during the path computation procedure. Otherwise, when cleared, this indicates that the SRLG information should not be collected. In a PCRep message, when the S bit is set this indicates that the returned path in ERO also carry the SRLG information; otherwise (when the S bit is cleared), the returned path does not carry SRLG information. 4.2. SRLG Subobject in ERO As per [RFC5440], ERO is used to encode the path of a TE LSP and is carried within a PCRep message to provide the computed path when computation was successful. The SRLG of a path is the union of the SRLGs of the links in the LSP [RFC4202]. The SRLG subobject is defined in [I-D.ietf-ccamp-rsvp-te-srlg-collect], as shown below: 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 | Reserved | Flags | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | SRLG ID 1 (4 bytes) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ ~ ...... ~ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | SRLG ID n (4 bytes) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Dhody, et al. Expires April 11, 2014 [Page 4] Internet-Draft PCE-SRLG October 2013 The meaning and description of Type, Length and SRLG ID can be found in [I-D.ietf-ccamp-rsvp-te-srlg-collect]. Bits in the Flags field is ignored. The SRLG subobject should be encoded inside the ERO object in the PCRep message when the S-Bit (SRLG) is set in the PCReq message. 5. Other Considerations 5.1. Backward Compatibility If a PCE receives a request and the PCE does not understand the new SRLG flag in the RP object, then the PCE SHOULD reject the request. If PCEP speaker receives a PCRep message with SRLG subobject that it does not support or recognize, it must act according to the existing processing rules. 5.2. Confidentiality via PathKey [RFC5520] defines a mechanism to hide the contents of a segment of a path, called the Confidential Path Segment (CPS). The CPS may be replaced by a path-key that can be conveyed in the PCEP and signaled within in a RSVP-TE ERO. When path-key confidentiality is used, collection of SRLG information and encoding this information in PCRep along with the path-key could be useful to compute a SRLG disjoint backup path at the later instance. 6. Security Considerations TBD. 7. Manageability Considerations 7.1. Control of Function and Policy TBD. 7.2. Information and Data Models TBD. 7.3. Liveness Detection and Monitoring TBD. Dhody, et al. Expires April 11, 2014 [Page 5] Internet-Draft PCE-SRLG October 2013 7.4. Verify Correct Operations TBD. 7.5. Requirements On Other Protocols TBD. 7.6. Impact On Network Operations TBD. 8. IANA Considerations IANA assigns values to PCEP parameters in registries defined in [RFC5440]. IANA is requested to make the following additional assignments. 8.1. New Subobjects for the ERO Object IANA has previously assigned an Object-Class and Object-Type to the ERO carried in PCEP messages [RFC5440]. IANA also maintains a list of subobject types valid for inclusion in the ERO. IANA is requested to assign one new subobject types for inclusion in the ERO as follows: Subobject Meaning Reference 34 (TBD) SRLG sub-object This document 9. Acknowledgments TBD. 10. References 10.1. Normative References [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. 10.2. Informative References [RFC4202] Kompella, K. and Y. Rekhter, "Routing Extensions in Support of Generalized Multi-Protocol Label Switching (GMPLS)", RFC 4202, October 2005. Dhody, et al. Expires April 11, 2014 [Page 6] Internet-Draft PCE-SRLG October 2013 [RFC4206] Kompella, K. and Y. Rekhter, "Label Switched Paths (LSP) Hierarchy with Generalized Multi-Protocol Label Switching (GMPLS) Traffic Engineering (TE)", RFC 4206, October 2005. [RFC4655] Farrel, A., Vasseur, J., and J. Ash, "A Path Computation Element (PCE)-Based Architecture", RFC 4655, August 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. [RFC5440] Vasseur, JP. and JL. Le Roux, "Path Computation Element (PCE) Communication Protocol (PCEP)", RFC 5440, March 2009. [RFC5520] Bradford, R., Vasseur, JP., and A. Farrel, "Preserving Topology Confidentiality in Inter-Domain Path Computation Using a Path-Key-Based Mechanism", RFC 5520, April 2009. [RFC6107] Shiomoto, K. and A. Farrel, "Procedures for Dynamically Signaled Hierarchical Label Switched Paths", RFC 6107, February 2011. [I-D.ietf-ccamp-rsvp-te-srlg-collect] Zhang, F., Li, D., Dios, O., Margaria, C., and M. Hartley, "RSVP-TE Extensions for Collecting SRLG Information", draft-ietf-ccamp-rsvp-te-srlg-collect-03 (work in progress), September 2013. [I-D.farrel-interconnected-te-info-exchange] Farrel, A., Drake, J., Bitar, N., Swallow, G., and D. Ceccarelli, "Problem Statement and Architecture for Information Exchange Between Interconnected Traffic Engineered Networks", draft-farrel-interconnected-te-info- exchange-01 (work in progress), July 2013. [I-D.zhang-ccamp-gmpls-uni-app] Zhang, F., Dios, O., Farrel, A., Zhang, X., and D. Ceccarelli, "Applicability of Generalized Multiprotocol Label Switching (GMPLS) User-Network Interface (UNI)", draft-zhang-ccamp-gmpls-uni-app-04 (work in progress), July 2013. Dhody, et al. Expires April 11, 2014 [Page 7] Internet-Draft PCE-SRLG October 2013 Appendix A. Contributor Addresses Udayasree Palle Huawei Technologies Leela Palace Bangalore, Karnataka 560008 INDIA EMail: udayasree.palle@huawei.com Avantika Huawei Technologies Leela Palace Bangalore, Karnataka 560008 INDIA EMail: avantika.sushilkumar@huawei.com Authors' Addresses Dhruv Dhody Huawei Technologies Leela Palace Bangalore, Karnataka 560008 INDIA EMail: dhruv.ietf@gmail.com Fatai Zhang Huawei Technologies Bantian, Longgang District Shenzhen, Guangdong 518129 P.R.China EMail: zhangfatai@huawei.com Xian Zhang Huawei Technologies Bantian, Longgang District Shenzhen, Guangdong 518129 P.R.China EMail: zhang.xian@huawei.com Dhody, et al. Expires April 11, 2014 [Page 8]