Internet DRAFT - draft-xu-ospf-service-sid-adv
draft-xu-ospf-service-sid-adv
Network Working Group X. Xu
Internet-Draft Huawei
Intended status: Standards Track April 25, 2014
Expires: October 27, 2014
Signaling Services and Service SIDs Using OSPF
draft-xu-ospf-service-sid-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 services and the corresponding service
segment IDs using OSPF.
Status of This Memo
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This Internet-Draft will expire on October 27, 2014.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
1.1. Requirements Language . . . . . . . . . . . . . . . . . . 2
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 2
3. Advertising Services and Service SIDs . . . . . . . . . . . . 2
3.1. Service TLVs . . . . . . . . . . . . . . . . . . . . . . 3
3.2. Service SID Sub-TLVs . . . . . . . . . . . . . . . . . . 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 . . . . . . . . . . . . . . . . . . . . . . . . 4
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 SFC (i.e,
steering traffic through the service function path). To allow the
service classifier to encode the segment list represeting a
particular service path, the classifier needs to know on which
service node(s) a given service is located and what segment ID (SID)
is used to indicate that service on a given service node. This
document describes how to advertise services and the corresponding
service SIDs using OSPF including 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 Services and Service SIDs
Service nodes within the network need to advertise each service they
are offering by using a TLV within the body of the OSPF Router
Information (RI) Opaque LSA [RFC4970]. These TLVs are called as
Service TLVs. These Service TLVs are applicable to both OSPFv2 and
OSPFv3. The scope of the advertisement depends on the application
but it is recommended that it SHOULD be domain-wide. Furthermore,
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they may need to allocate at least one corresponding SID for each
service and meanwhile advertise it by using a sub-TLV of the
corresponding Service TLV for that service, called Service SID sub-
TLV. In the MPLS-SR case, service nodes within the network would
allocate a locally significant MPLS label to each service 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 they are offering. For a given service, the service node
offering that service could advertise the service ID in MPLS label
format or the one in IPv6 address format, or both.
3.1. Service TLVs
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 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
~ Sub-TLVs ~
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Type: each service is allocated with a unique type code.
Length: variable
Value: contains zero or more sub-TLVs. Besides the Service SID
sub-TLVs, other sub-TLVs (to be defined in future) which are used
to describe some characters of a service could also be contained
in this field.
3.2. Service SID Sub-TLVs
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 SID ~
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Type: TBD1 for the service SID in MPLS label format and TBD2 for
the service SID in IPv6 address format.
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.
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4. Acknowledgements
TBD.
5. IANA Considerations
TBD.
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.
[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", draft-filsfils-spring-
segment-routing-00 (work in progress), April 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.
Author's Address
Xiaohu Xu
Huawei
Email: xuxiaohu@huawei.com
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