LSR Working Group Yao. Liu
Internet-Draft Zheng. Zhang
Intended status: Standards Track ZTE Corporation
Expires: July 18, 2020 January 15, 2020
IGP Extentions for Segment Routing Service Segment
draft-lz-lsr-igp-sr-service-segments-00
Abstract
This document defines extensions to the link-state routing protocols
(IS-IS and OSPF) in order to carry service segment information via
IGP.
Status of This Memo
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. IGP Extensions for Service Segments . . . . . . . . . . . . . 3
2.1. IS-IS Extentions . . . . . . . . . . . . . . . . . . . . 4
2.2. OSPF Extentions . . . . . . . . . . . . . . . . . . . . . 5
3. Security Considerations . . . . . . . . . . . . . . . . . . . 6
4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 6
5. References . . . . . . . . . . . . . . . . . . . . . . . . . 6
5.1. Normative References . . . . . . . . . . . . . . . . . . 6
5.2. Informative References . . . . . . . . . . . . . . . . . 7
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 7
1. Introduction
Segments are introduced in the SR architecture [RFC8402]. Segment
Routing (SR) allows for a flexible definition of end-to-end paths by
encoding paths as sequences of topological sub-paths, called
"segments".
Service Function Chaining (SFC) [RFC7665] provides support for the
creation of composite services that consist of an ordered set of
Service Functions (SF) that are to be applied to packets and/or
frames selected as a result of classification.
[I-D.ietf-spring-sr-service-programming] describes how a service can
be associated with a SID and how to achieve service funtion chaining
in SR-enabled MPLS and IPv6 networks. It also defines SR-aware and
SR-unaware services. For a SR-unaware service ,there has to be a SR
proxy handling the SR processing on behalf of the service .
[I-D.dawra-idr-bgp-ls-sr-service-segments] propose extensions to BGP-
LS for Service Chaining to distribute the service segment information
to SR Controller.
We reuse the network topology and concepts in
[I-D.dawra-idr-bgp-ls-sr-service-segments] . The network is shown in
figure 1.
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SR-C
|
|
A----1----2----3----4----5----B
| |
| |
S1 S2 proxy----S2
Figure 1: Network with Services
Node 1-5 are nodes capital of segment routing. A and B are two end
hosts. S1 is an SR-aware Service. S2 is an SR-unaware Service.
SR Controller (SR-C) is connected to node 1, but may be attached to
any node 1-5 in the network.
SR-C is capable of receiving BGP-LS updates to discover topology, and
calculating constrained paths between 1 and 5.
If node 1 gets the service segment information, it can use the BGP-LS
extensions [I-D.ietf-spring-sr-service-programming] to advertise it
to the SR-C, but how can node 1 get it is a question.but node 1 must
get the service segment information from other nodes at first.
This document proposes extensions for IGP to broadcastadvertise
service segment information so that there is only one SR node needed
per Autonomous System to be connected with the SR-C through BGP-LS to
advertise the information to it.
This extension works for both SR-MPLS and SRv6.
2. IGP Extensions for Service Segments
After an SFF like node 2 or node 4 get the service segment
information, it needs to advertise the information to other SR nodes
in the domain through IGP.
How can SFFs like node 2 and node 4 get the service segment
information from S1 and S2 proxy will be discussed further.
There may be other alternate mechanisms and are outside of scope of
this document.
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2.1. IS-IS Extentions
This document intrduces new TLVs for SRv6 End SID sub-TLV
[I-D.ietf-lsr-isis-srv6-extensions] and SID/Label sub-TLV [RFC8666]
for SR-MPLS to associate the Service SID Value with Service-related
Information.
One of the new TLVs is Service Chaining (SC) TLV, the definition and
structure is the same as the SC TLV defined in
[I-D.dawra-idr-bgp-ls-sr-service-segments] chapter 2.
+---------------------------------------+
| Type (1 octet) |
+---------------------------------------+
| Length (1 octet) |
+---------------------------------------+
| Service Type(ST) (2 octet) |
+---------------------------------------+
| Flags (1 octet) |
+---------------------------------------+
| Traffic Type(1 octet) |
+---------------------------------------+
| RESERVED (2 octet) |
+---------------------------------------+
Service Chaining (SC) TLV
Another Optional Opaque Metadata(OM) TLV is defined in figure 3. The
definition and structure is the same as the OM TLV defined in
[I-D.dawra-idr-bgp-ls-sr-service-segments] chapter 2.
+---------------------------------------+
| Type (1 octet) |
+---------------------------------------+
| Length (1 octet) |
+---------------------------------------+
| Opaque Type (2 octet) |
+---------------------------------------+
| Flags (1 octet) |
+---------------------------------------+
| Value (variable) |
+---------------------------------------+
Opaque Metadata(OM) TLV
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2.2. OSPF Extentions
This document intrduces new TLVs for SRv6 End SID sub-TLV
[I-D.li-ospf-ospfv3-srv6-extensions] and SID/Label sub-TLV
[RFC8665]for SR-MPLS to associate the Service SID Value with Service-
related Information.
One of the new TLVs is Service Chaining (SC) TLV, the definition and
structure is the same as the SC TLV defined in
[I-D.dawra-idr-bgp-ls-sr-service-segments] chapter 2.
+---------------------------------------+
| Type (2 octet) |
+---------------------------------------+
| Length (2 octet) |
+---------------------------------------+
| Service Type(ST) (2 octet) |
+---------------------------------------+
| Flags (1 octet) |
+---------------------------------------+
| Traffic Type(1 octet) |
+---------------------------------------+
| RESERVED (2 octet) |
+---------------------------------------+
Service Chaining (SC) TLV
Another Optional Opaque Metadata(OM) TLV is defined in figure 3. The
definition and structure is the same as the OM TLV defined in
[I-D.dawra-idr-bgp-ls-sr-service-segments] chapter 2.
+---------------------------------------+
| Type (2 octet) |
+---------------------------------------+
| Length (2 octet) |
+---------------------------------------+
| Opaque Type (2 octet) |
+---------------------------------------+
| Flags (1 octet) |
+---------------------------------------+
| Value (variable) |
+---------------------------------------+
Opaque Metadata(OM) TLV
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3. Security Considerations
Procedures and protocol extensions defined in this document do not
affect the IS-IS and OSPF security model
4. IANA Considerations
TBD
5. References
5.1. Normative References
[I-D.dawra-idr-bgp-ls-sr-service-segments]
Dawra, G., Filsfils, C., Talaulikar, K., Clad, F.,
daniel.bernier@bell.ca, d., Uttaro, J., Decraene, B.,
Elmalky, H., Xu, X., Guichard, J., and C. Li, "BGP-LS
Advertisement of Segment Routing Service Segments", draft-
dawra-idr-bgp-ls-sr-service-segments-03 (work in
progress), January 2020.
[I-D.ietf-lsr-isis-srv6-extensions]
Psenak, P., Filsfils, C., Bashandy, A., Decraene, B., and
Z. Hu, "IS-IS Extension to Support Segment Routing over
IPv6 Dataplane", draft-ietf-lsr-isis-srv6-extensions-03
(work in progress), October 2019.
[I-D.ietf-spring-sr-service-programming]
Clad, F., Xu, X., Filsfils, C., daniel.bernier@bell.ca,
d., Li, C., Decraene, B., Ma, S., Yadlapalli, C.,
Henderickx, W., and S. Salsano, "Service Programming with
Segment Routing", draft-ietf-spring-sr-service-
programming-01 (work in progress), November 2019.
[I-D.li-ospf-ospfv3-srv6-extensions]
Li, Z., Hu, Z., Cheng, D., Talaulikar, K., and P. Psenak,
"OSPFv3 Extensions for SRv6", draft-li-ospf-
ospfv3-srv6-extensions-07 (work in progress), November
2019.
[RFC7665] Halpern, J., Ed. and C. Pignataro, Ed., "Service Function
Chaining (SFC) Architecture", RFC 7665,
DOI 10.17487/RFC7665, October 2015,
<https://www.rfc-editor.org/info/rfc7665>.
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[RFC8665] Psenak, P., Ed., Previdi, S., Ed., Filsfils, C., Gredler,
H., Shakir, R., Henderickx, W., and J. Tantsura, "OSPF
Extensions for Segment Routing", RFC 8665,
DOI 10.17487/RFC8665, December 2019,
<https://www.rfc-editor.org/info/rfc8665>.
[RFC8666] Psenak, P., Ed. and S. Previdi, Ed., "OSPFv3 Extensions
for Segment Routing", RFC 8666, DOI 10.17487/RFC8666,
December 2019, <https://www.rfc-editor.org/info/rfc8666>.
5.2. Informative References
[RFC8402] Filsfils, C., Ed., Previdi, S., Ed., Ginsberg, L.,
Decraene, B., Litkowski, S., and R. Shakir, "Segment
Routing Architecture", RFC 8402, DOI 10.17487/RFC8402,
July 2018, <https://www.rfc-editor.org/info/rfc8402>.
Authors' Addresses
Liu Yao
ZTE Corporation
No. 50 Software Ave, Yuhuatai Distinct
Nanjing
China
Email: liu.yao71@zte.com.cn
Zheng Zhang
ZTE Corporation
No. 50 Software Ave, Yuhuatai Distinct
Nanjing
China
Email: zzhang_ietf@hotmail.com
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