Network Working Group F. Zhang, Ed. Internet-Draft D. Li Intended status: Standards Track Huawei Expires: April 25, 2013 O. Gonzalez de Dios, Ed. Telefonica I+D C. Margaria Nokia Siemens Networks M. Hartley Cisco October 22, 2012 RSVP-TE Extensions for Collecting SRLG Information draft-ietf-ccamp-rsvp-te-srlg-collect-01 Abstract This document provides extensions for the Resource ReserVation Protocol-Traffic Engineering (RSVP-TE) to support automatic collection of Shared Risk Link Group (SRLG) Information for the TE link formed by a LSP. 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 25, 2013. 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 Zhang, et al. Expires April 25, 2013 [Page 1] Internet-Draft RSVP-TE Ext for Collecting SRLG October 2012 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. RSVP-TE Requirements . . . . . . . . . . . . . . . . . . . . . 3 2.1. SRLG Collection Indication . . . . . . . . . . . . . . . . 3 2.2. SRLG Collection . . . . . . . . . . . . . . . . . . . . . . 3 2.3. SRLG Update . . . . . . . . . . . . . . . . . . . . . . . . 3 3. RSVP-TE Extensions (Encoding) . . . . . . . . . . . . . . . . . 3 3.1. SRLG Collection Flag . . . . . . . . . . . . . . . . . . . 4 3.2. SRLG sub-object . . . . . . . . . . . . . . . . . . . . . . 4 4. Signaling Procedures . . . . . . . . . . . . . . . . . . . . . 5 4.1. SRLG Collection . . . . . . . . . . . . . . . . . . . . . . 5 4.2. SRLG Update . . . . . . . . . . . . . . . . . . . . . . . . 6 5. Manageability Considerations . . . . . . . . . . . . . . . . . 7 5.1. Policy Configuration . . . . . . . . . . . . . . . . . . . 7 5.2. Coherent SRLG IDs . . . . . . . . . . . . . . . . . . . . . 7 6. Security Considerations . . . . . . . . . . . . . . . . . . . . 7 7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 7 7.1. RSVP Attribute Bit Flags . . . . . . . . . . . . . . . . . 8 7.2. ROUTE_RECORD Object . . . . . . . . . . . . . . . . . . . . 8 8. Contributing Authors . . . . . . . . . . . . . . . . . . . . . 8 9. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 8 10. Normative References . . . . . . . . . . . . . . . . . . . . . 9 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 9 Zhang, et al. Expires April 25, 2013 [Page 2] Internet-Draft RSVP-TE Ext for Collecting SRLG October 2012 1. Introduction 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]. On the other hand, as described in [RFC4206] and [RFC6107], H-LSP (Hierarchical LSP) or S-LSP (stitched LSP) can be used for carrying one or more other LSPs. Both of the H-LSP and S-LSP can be formed as a TE link. In such cases, it is important to know the SRLG information of the LSPs that will be used to carry further LSPs. This document provides an automatic mechanism to collect the SRLG for the TE link formed by a LSP. Note that how to use the collected SRLG information is out of scope of this document 2. RSVP-TE Requirements 2.1. SRLG Collection Indication The head nodes of the LSP must be capable of indicating whether the SRLG information of the LSP should be collected during the signaling procedure of setting up an LSP. SRLG information should not be collected without an explicit request for it being made by the head node. 2.2. SRLG Collection If requested, the SRLG information should be collected during the setup of an LSP. The endpoints of the LSP may use the collected SRLG information and use it for routing, sharing and TE link configuration purposes. 2.3. SRLG Update When the SRLG information of an existing LSP for which SRLG information was collected during signaling changes, the relevant nodes of the LSP must be capable of updating the SRLG information of the LSP. This means that that the signaling procedure must be capable of updating the new SRLG information. 3. RSVP-TE Extensions (Encoding) Zhang, et al. Expires April 25, 2013 [Page 3] Internet-Draft RSVP-TE Ext for Collecting SRLG October 2012 3.1. SRLG Collection Flag In order to indicate nodes that SRLG collection is desired, this document defines a new flag in the Attribute Flags TLV, which is carried in an LSP_REQUIRED_ATTRIBUTES Object: [Editor's note: LSP_ATTRIBUTES Object is also under consideration] o Bit Number (to be assigned by IANA, recommended bit zero): SRLG Collection flag The SRLG Collection flag is meaningful on a Path message. If the SRLG Collection flag is set to 1, it means that the SRLG information should be reported to the head and tail node along the setup of the LSP. The rules of the processing of the Attribute Flags TLV are not changed. 3.2. SRLG sub-object This document defines a new RRO sub-object (ROUTE_RECORD sub-object) to record the SRLG information of the LSP. Its format is modeled on the RRO sub-objects defined in RFC 3209 [RFC3209]. 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) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Type The type of the sub-object, to be assigned by IANA, which is recommended 34. Length The Length contains the total length of the sub-object in bytes, including the Type and Length fields. The Length depends on the number of SRLG IDs. Flags Zhang, et al. Expires April 25, 2013 [Page 4] Internet-Draft RSVP-TE Ext for Collecting SRLG October 2012 The Flags are used to indicate properties of the SRLG-list contained in the sub-object. 0x01 = SRLG-list edited If set, this flag indicates that the SRLG-list contained in the RRO sub-object has been edited in some way by a node during signaling in accordance with that node's policy. 0x02 = Partial SRLG-list If set, this flag indicates that the SRLG-list contained in this RRO sub-object is known to be incomplete. SRLG Id The 32-bit identifier of the SRLG. Reserved This field is reserved. It SHOULD be set to zero on transmission and MUST be ignored on receipt. The rules of the processing of the LSP_REQUIRED_ATTRIBUTES Object and ROUTE_RECORD Object are not changed.[Editor's note: The rules of processing LSP_ATTRIBUTES Object (which is under consideration) are also not changed] 4. Signaling Procedures 4.1. SRLG Collection Typically, the head node gets the route information of an LSP by adding a RRO which contains the sender's IP addresses in the Path message. If a head node also desires SRLG recording, it sets the SRLG Collection Flag in the Attribute Flags TLV which can be carried in an LSP_REQUIRED_ATTRIBUTES Object. When a node receives a Path message which carries an LSP_REQUIRED_ATTRIBUTES Object and the SRLG Collection Flag is set, if local policy determines that the SRLG information should not be provided to the endpoints, it must return a PathErr message to reject the Path message. Otherwise, it must add an SRLG sub-object to the RRO to carry the local SRLG information. Then it forwards the Path message to the next node in the downstream direction. [Editor's note: It is under consideration that with the Path message Zhang, et al. Expires April 25, 2013 [Page 5] Internet-Draft RSVP-TE Ext for Collecting SRLG October 2012 carries an LSP_REQUIRED_ATTRIBUTES Object and the SRLG Collection Flag is set, if local policy determines that the SRLG information should not be provided to the endpoints, the Path message should not rejected and the SRLG sub-object must not added] Following the steps described above, the intermediate nodes of the LSP can collect the SRLG information in the RRO during the forwarding of the Path message hop by hop. When the Path message arrives at the tail node, the tail node can get the SRLG information from the RRO. Before the Resv message is sent to the upstream node, the tail node adds an SRLG sub-object to the RRO. The collected SRLG information can be carried in the SRLG sub-object. Therefore, during the forwarding of the Resv message in the upstream direction, the SRLG information is not needed to be collected hop by hop. Based on the above procedure, the endpoints can get the SRLG information automatically. Then the endpoints can for instance advertise it as a TE link to the routing instance based on the procedure described in [RFC6107] and configure the SRLG information of the FA automatically. It is noted that a node (e.g. the edge node of a domain) may edit the RRO to remove the route information (e.g. node, interface identifier information) before forwarding it due to some reasons (e.g.confidentiality or reduce the size of RRO). A node MAY edit SRLG information within the RRO of a Path or Resv message if dictated by its local policy. If a node makes such an alteration to an existing RRO object, it SHOULD set the "SRLG-list edited" flag in the edited RRO sub-object to indicate to other nodes that this has been done. [Editor's note: Two behaviors are under consideration: using LSP_REQUIRED_ATTRIBUTES the collection is mandatory, while using LSP_ATTRIBUTES the collection is desired, but not mandatory] 4.2. SRLG Update When the SRLG information of a link is changed, the LSPs using that link should be aware of the changes. The procedures defined in Section 4.4.3 of RFC 3209 [RFC3209] MUST be used to refresh the SRLG information if the SRLG change is to be communicated to other nodes according to the local node's policy. If local policy is that the SRLG change should be suppressed or would result in no change to the previously signaled SRLG-list, the node need not send an update Zhang, et al. Expires April 25, 2013 [Page 6] Internet-Draft RSVP-TE Ext for Collecting SRLG October 2012 5. Manageability Considerations 5.1. Policy Configuration In a border node of inter-domain or inter-layer network, the following SRLG processing policy should be capable of being configured: o Whether the SRLG IDs of the domain or specific layer network can be exposed to the nodes outside the domain or layer network, or whether they should be summarized or removed entirely. o If SRLGs are summarized or removed, whether the "SRLG-list edited" flag is set in affected SRLG RRO-sub-objects. o If the SRLG IDs must not be exposed to the nodes outside of the domain or specific layer network by policy, the border node must reject the Path message desiring SRLG recording and send a PathErr message with the defined error code 'Policy Control Failure'/'Inter-domain policy failure'. [Editor's note: This last statement may be removed in next versions and do not impose such rejection.] 5.2. Coherent SRLG IDs In a multi-layer multi-domain scenario, SRLG ids may be configured by different management entities in each layer/domain. In such scenarios, maintaining a coherent set of SRLG IDs is a key requirement in order to be able to use the SRLG information properly. Thus, SRLG IDs must be unique. Note that current procedure is targeted towards a scenario where the different layers and domains belong to the same operator, or to several coordinated administrative groups. Further scenarios, where coherence in the SRLG IDs cannot be guaranteed are out of the scope of the present document and are left for further study. 6. Security Considerations TBD. 7. IANA Considerations Zhang, et al. Expires April 25, 2013 [Page 7] Internet-Draft RSVP-TE Ext for Collecting SRLG October 2012 7.1. RSVP Attribute Bit Flags The IANA has created a registry and manages the space of attributes bit flags of Attribute Flags TLV as described in section 11.3 of [RFC5420]. It is requested that the IANA makes assignments from the Attribute Bit Flags. This document introduces a new Attribute Bit Flag: o Bit number: TBD (10) o Defining RFC: this I-D o Name of bit: SRLG Collection Flag o The meaning of the Attribute Flags TLV on a Path is defined in this I-D 7.2. ROUTE_RECORD Object IANA has made the following assignments in the "Class Names, Class Numbers, and Class Types" section of the "RSVP PARAMETERS" registry located at http://www.iana.org/assignments/rsvp-parameters. We request that IANA make assignments from the ROUTE_RECORD RFC 3209 [RFC3209] portions of this registry. This document introduces a new RRO sub-object: Type Name Reference --------- ---------------------- --------- TBD (34) SRLG sub-object This I-D 8. Contributing Authors Zafar Ali Cisco Systems zali@cisco.com 9. Acknowledgements The authors would like to thank Igor Bryskin, Ramon Casellas and Lou Berger for their useful comments to the document. Zhang, et al. Expires April 25, 2013 [Page 8] Internet-Draft RSVP-TE Ext for Collecting SRLG October 2012 10. Normative References [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. [RFC4202] Kompella, K. and Y. Rekhter, "Routing Extensions in Support of Generalized Multi-Protocol Label Switching (GMPLS)", RFC 4202, October 2005. [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. [RFC5150] Ayyangar, A., Kompella, K., Vasseur, JP., and A. Farrel, "Label Switched Path Stitching with Generalized Multiprotocol Label Switching Traffic Engineering (GMPLS TE)", RFC 5150, February 2008. [RFC6107] Shiomoto, K. and A. Farrel, "Procedures for Dynamically Signaled Hierarchical Label Switched Paths", RFC 6107, February 2011. Authors' Addresses Fatai Zhang (editor) Huawei F3-5-B RD Center Bantian, Longgang District, Shenzhen 518129 P.R.China Phone: Email: zhangfatai@huawei.com Dan Li Huawei F3-5-B RD Center Bantian, Longgang District, Shenzhen 518129 P.R.China Phone: Email: danli@huawei.com Zhang, et al. Expires April 25, 2013 [Page 9] Internet-Draft RSVP-TE Ext for Collecting SRLG October 2012 Oscar Gonzalez de Dios (editor) Telefonica I+D Don Ramon de la Cruz Madrid, 28006 Spain Phone: +34 913328832 Email: ogondio@tid.es Cyril Margaria Nokia Siemens Networks St Martin Strasse 76 Munich, 81541 Germany Phone: +49 89 5159 16934 Email: cyril.margaria@nsn.com Matt Hartley Cisco Phone: Email: mhartley@cisco.com Zhang, et al. Expires April 25, 2013 [Page 10]