Network Working Group X. Xu
Internet-Draft N. Wu
Intended status: Standards Track Huawei
Expires: December 20, 2014 H. Shah
Ciena
June 18, 2014

Advertising Service Functions Using OSPF
draft-xu-ospf-service-function-adv-01

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 their corresponding characters (e.g.,service function segment ID) using OSPF. Here the OSPF means both OSPFv2 and OSPFv3.

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 December 20, 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.


Table of Contents

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 a service classifier to encode the segment list representing 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 characters (e.g.,service function segment ID) using OSPF. Here the OSPF means both OSPFv2 [RFC2328] and OSPFv3 [RFC2740].

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 [RFC4970].

3. Advertising Service Functions and Corresponding SIDs

Service nodes within the network need to advertise each service function they are offering by using a TLV within the body of the OSPF Router Information (RI) Opaque LSA [RFC4970]. This new TLV is called as Service Function TLV. The Service Function TLV is applicable to both OSPFv2 and OSPFv3. The Service Function TLV could appear multiple times wihin a given Router Information (RI) Opaque LSA 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 recommended that it SHOULD be domain-wide. Furthermore, service nodes need to allocate a corresponding SID to each service function and meanwhile advertise it by using a sub-TLV of the above Service Function 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 format of an MPLS label, an IPv6 address, or both.

3.1. Service Function 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                             ~
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

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                       ~
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

4. Acknowledgements

TBD.

5. IANA Considerations

This memo includes a request to IANA for allocating one TLV type code for the Service Function TLV, and one sub-TLV type code 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", Internet-Draft draft-xu-spring-sfc-use-case-00, April 2014.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC4970] Lindem, A., Shen, N., Vasseur, JP., Aggarwal, R. and S. Shaffer, "Extensions to OSPF for Advertising Optional Router Capabilities", RFC 4970, 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", Internet-Draft draft-filsfils-spring-segment-routing-03, June 2014.
[RFC2328] Moy, J., "OSPF Version 2", STD 54, RFC 2328, April 1998.
[RFC2740] Coltun, R., Ferguson, D. and J. Moy, "OSPF for IPv6", RFC 2740, December 1999.

Authors' Addresses

Xiaohu Xu Huawei EMail: xuxiaohu@huawei.com
Nan Wu Huawei EMail: eric.wu@huawei.com
Himanshu Shah Ciena EMail: hshah@ciena.com