Network Working Group X. Xu Internet-Draft Huawei Intended status: Standards Track May 29, 2014 Expires: November 30, 2014 Advertising Service Functions Using IS-IS draft-xu-isis-service-function-adv-00 Abstract The Segment Routing mechanism can be leveraged to realize the service path layer functionality of the Service Function Chaining (i.e, steering traffic through the service function path). This document describes how to advertise service functions and the corresponding segment IDs using IS-IS. 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 November 30, 2014. Copyright Notice Copyright (c) 2014 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. Xu Expires November 30, 2014 [Page 1] Internet-Draft Advertising Service Functions Using IS-IS May 2014 Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 1.1. Requirements Language . . . . . . . . . . . . . . . . . . 2 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 2 3. Advertising Service Functions and Corresponding SIDs . . . . 2 3.1. Service Function Sub-TLV . . . . . . . . . . . . . . . . 3 3.2. Service Function SID Sub-TLV . . . . . . . . . . . . . . 3 4. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 4 5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 4 6. Security Considerations . . . . . . . . . . . . . . . . . . . 4 7. References . . . . . . . . . . . . . . . . . . . . . . . . . 4 7.1. Normative References . . . . . . . . . . . . . . . . . . 4 7.2. Informative References . . . . . . . . . . . . . . . . . 4 Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 5 1. Introduction [I-D.xu-spring-sfc-use-case] describes a particular use case for SPRING where the Segment Routing (SR) mechanism is leveraged to realize the service path layer functionality of the Service Function Chaining (SFC), i.e, steering traffic through the service function path. To allow the service classifier to encode the segment list represeting a particular service function path, the classifier needs to know on which service node(s) a given service function is located and what segment ID (SID) is used to indicate that service function on a given service node. This document describes how to advertise service functions and their corresponding SIDs using IS-IS. 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 RFC 2119 [RFC2119]. 2. Terminology This memo makes use of the terms defined in [RFC4971]. 3. Advertising Service Functions and Corresponding SIDs Service nodes within the network need to advertise each service function they are offering by using a new sub-TLV of the IS-IS Router CAPABILITY TLV [RFC4971]. This new sub-TLV is called as Service Function sub-TLV. The Service Function sub-TLV could appear multiple times wihin a given IS-IS Router CAPABILITY TLV when more than one service function needs to be advertised by a given service node. The scope of the advertisement depends on the application but it is Xu Expires November 30, 2014 [Page 2] Internet-Draft Advertising Service Functions Using IS-IS May 2014 recommended that it SHOULD be domain-wide. Furthermore, service nodes need to allocate a corresponding SID to each service function they are offering and advertise it by using a sub-TLV of the above Service Function sub-TLV, called Service Function SID sub-TLV. In the MPLS-SR case, service nodes within the network would allocate a locally significant MPLS label to each service function they are offering. In the IPv6-SR case, service nodes within the network would allocate a locally unique link-local IPv6 address to each service function they are offering. For a given service function, the service node offering that service function could advertise the corresponding SID in the MPLS label format or in the IPv6 address format, or both. 3.1. Service Function Sub-TLV 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 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Service Function Identifier | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ ~ Sub-TLVs ~ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Type: TBD. Length: variable. Service Function Identifier: A unique identifier that represents a service function within an SFC-enabled domain. Sub-TLVs: contains zero or more sub-TLVs related to service functions. Besides the Service Function SID sub-TLVs as defined in Section 3.2, other sub-TLVs (to be defined in future) which are used to describe some characters of a given service function could also be added. 3.2. Service Function SID Sub-TLV 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 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ ~ Service Function SID ~ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Xu Expires November 30, 2014 [Page 3] Internet-Draft Advertising Service Functions Using IS-IS May 2014 Type: TBD. Length: variable (3 or 16). Value: if the Length is set to 3, the 20 rightmost bits represent a MPLS label. If the length is set to 16, the value represents an IPv6 address. 4. Acknowledgements TBD. 5. IANA Considerations This memo includes a request to IANA to allocate one sub-TLV type codes within the IS-IS Router Capability TLV for the Service Function sub-TLV, and one sub-TLV type code within the Service Function sub- TLV for the Service Function SID sub-TLV. 6. Security Considerations This document does not introduce any new security risk. 7. References 7.1. Normative References [I-D.xu-spring-sfc-use-case] Xu, X., "Service Function Chaining Use Case", draft-xu- spring-sfc-use-case-00 (work in progress), April 2014. [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. [RFC4971] Vasseur, JP., Shen, N., and R. Aggarwal, "Intermediate System to Intermediate System (IS-IS) Extensions for Advertising Router Information", RFC 4971, July 2007. 7.2. Informative References [I-D.filsfils-spring-segment-routing] Filsfils, C., Previdi, S., Bashandy, A., Decraene, B., Litkowski, S., Horneffer, M., Milojevic, I., Shakir, R., Ytti, S., Henderickx, W., Tantsura, J., and E. Crabbe, "Segment Routing Architecture", draft-filsfils-spring- segment-routing-02 (work in progress), May 2014. Xu Expires November 30, 2014 [Page 4] Internet-Draft Advertising Service Functions Using IS-IS May 2014 Author's Address Xiaohu Xu Huawei Email: xuxiaohu@huawei.com Xu Expires November 30, 2014 [Page 5]