Internet DRAFT - draft-xu-ospf-service-function-adv
draft-xu-ospf-service-function-adv
Network Working Group X. Xu
Internet-Draft N. Wu
Intended status: Standards Track Huawei
Expires: December 31, 2014 H. Shah
Ciena
L. Contreras
Telefonica I+D
June 29, 2014
Advertising Service Functions Using OSPF
draft-xu-ospf-service-function-adv-02
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
attributes (e.g., 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
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This Internet-Draft will expire on December 31, 2014.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
1.1. Requirements Language . . . . . . . . . . . . . . . . . . 2
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 2
3. Advertising Service Functions and Corresponding SIDs . . . . 3
3.1. Service Function TLV . . . . . . . . . . . . . . . . . . 3
3.2. Service Function SID Sub-TLV . . . . . . . . . . . . . . 4
4. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 4
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 4
6. Security Considerations . . . . . . . . . . . . . . . . . . . 4
7. References . . . . . . . . . . . . . . . . . . . . . . . . . 4
7.1. Normative References . . . . . . . . . . . . . . . . . . 4
7.2. Informative References . . . . . . . . . . . . . . . . . 5
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 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 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 attributes (e.g., SID)
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] and
[I-D.xu-spring-sfc-use-case].
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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 ~
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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 corresponding to the
particular attributes of a given service function. The Service
Function SID sub-TLV as defined in Section 3.2 is one such sub-TLV
which is used to indicate the corrresponding service function SID.
Other sub-TLVs are to be defined in the future.
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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 ~
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Type: TBD
Length: variable (3 or 16).
Value: if the Length is set to 3, the rightmost 20 bits represent
an 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 for allocating type codes for
the Service Function sub-TLV and 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., Li, Z., and H. Shah, "Service Function Chaining
Use Case for SPRING", draft-xu-spring-sfc-use-case-01
(work in progress), June 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.
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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-03 (work in progress), 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
Luis M. Contreras
Telefonica I+D
Ronda de la Comunicacion, s/n
Sur-3 building, 3rd floor
Madrid, 28050
Spain
Email: luismiguel.contrerasmurillo@telefonica.com
URI: http://people.tid.es/LuisM.Contreras/
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