ISIS Working Group X. Xu
Internet-Draft N. Wu
Intended status: Standards Track Huawei
Expires: May 4, 2017 H. Shah
Ciena
L. Contreras
Telefonica I+D
October 31, 2016
Advertising Service Functions Using IS-IS
draft-xu-isis-service-function-adv-04
Abstract
Source Packet Routing in Networking (SPRING) WG is developing an MPLS
source routing mechanism. This MPLS source routing mechanism can be
leveraged to realize the service path layer functionality of the
service function chaining (i.e., steering the selected traffic
through a particular service function path) by encoding the service
function path information as an MPLS label stack. This document
describes how to advertise service functions and their corresponding
attributes (e.g.,segment ID) using IS-IS.
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].
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 May 4, 2017.
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Copyright Notice
Copyright (c) 2016 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
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the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3
3. Solution Description . . . . . . . . . . . . . . . . . . . . 3
3.1. Service Function Sub-TLV . . . . . . . . . . . . . . . . 3
3.2. SF 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-mpls-service-chaining] describes how to leverage MPLS-SPRING
[I-D.ietf-spring-segment-routing-mpls] (a.k.a., an MPLS-based source
routing mechanism) to realize the service path layer functionality of
the Service Function Chaining (SFC), i.e, steering traffic through
the Service Function Path (SFP). To allow a service classifier to
attach the segment list (i.e., an MPLS label stack) which represents
a particular SFP to the selected traffic, the service classifier
needs to know on which Service Function Forwarder (SFF) a given
Service Function (SF) is located and what segment ID (SID) is used to
indicate that SF. This document describes how to advertise Service
Functions (SFs) and their corresponding attributes (e.g.,SID) using
IS-IS.
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2. Terminology
This memo makes use of the terms defined in
[I-D.xu-mpls-service-chaining] and [RFC4971].
3. Solution Description
SFFs within the SFC domain need to advertise each SF 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 SF needs to be
advertised. The scope of the advertisement depends on the
application but it is recommended that it SHOULD be domain-wide.
Furthermore, SFFs need to allocate a corresponding SID to each SF
they are offering and advertise it by using a sub-TLV of the above
Service Function sub-TLV, called SF SID sub-TLV. To support the
approach of encoding SFP information in the form of an MPLS label
stack as described in [I-D.xu-mpls-service-chaining], SFFs SHOULD
allocate a locally significant MPLS label to each SF they are
offering.
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=TBD1 | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Service Function Identifier |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
~ Sub-TLVs ~
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Type: TBD1.
Length: variable. Service Function Identifier: A unique
identifier that represents an SF within an SFC-enabled domain.
Sub-TLVs: contains zero or more sub-TLVs corresponding to the
particular attributes of a given SF. The SF SID sub-TLV as
defined in Section 3.2 is one such sub-TLV which is used to
indicate the corrresponding SF SID. Other sub-TLVs are to be
defined in the future.
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3.2. SF 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=TBD2 | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Resv | SF SID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Type: TBD2.
Length: 3.
Sub-TLVs: The rightmost 20 bits represent an MPLS label which is
the SF SID of the corresponding SF.
4. Acknowledgements
TBD.
5. IANA Considerations
This document includes a request to IANA for allocating type codes
for the Service Function sub-TLV and the SF SID sub-TLV.
6. Security Considerations
This document does not introduce any new security risk.
7. References
7.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997,
<http://www.rfc-editor.org/info/rfc2119>.
[RFC4971] Vasseur, JP., Ed., Shen, N., Ed., and R. Aggarwal, Ed.,
"Intermediate System to Intermediate System (IS-IS)
Extensions for Advertising Router Information", RFC 4971,
DOI 10.17487/RFC4971, July 2007,
<http://www.rfc-editor.org/info/rfc4971>.
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7.2. Informative References
[I-D.ietf-sfc-architecture]
Halpern, J. and C. Pignataro, "Service Function Chaining
(SFC) Architecture", draft-ietf-sfc-architecture-11 (work
in progress), July 2015.
[I-D.ietf-spring-segment-routing-mpls]
Filsfils, C., Previdi, S., Bashandy, A., Decraene, B.,
Litkowski, S., Horneffer, M., Shakir, R.,
jefftant@gmail.com, j., and E. Crabbe, "Segment Routing
with MPLS data plane", draft-ietf-spring-segment-routing-
mpls-05 (work in progress), July 2016.
[I-D.xu-mpls-service-chaining]
Xu, X., Bryant, S., Assarpour, H., Shah, H., Contreras,
L., and d. daniel.bernier@bell.ca, "Service Chaining using
MPLS Source Routing", draft-xu-mpls-service-chaining-00
(work in progress), October 2016.
Authors' Addresses
Xiaohu Xu
Huawei
Email: xuxiaohu@huawei.com
Nan Wu
Huawei
Email: eric.wu@huawei.com
Himanshu Shah
Ciena
Email: hshah@ciena.com
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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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