Internet DRAFT - draft-li-pce-pcep-ls-sr-extension
draft-li-pce-pcep-ls-sr-extension
Network Working Group Z. Li
Internet-Draft X. Chen
Intended status: Standards Track N. Wu
Expires: May 3, 2017 Huawei Technologies
October 30, 2016
PCEP Link-State extensions for Segment Routing
draft-li-pce-pcep-ls-sr-extension-01
Abstract
Segment Routing leverages source routing. A node steers a packet
through a controlled set of instructions, called segments, by
prepending the packet with an SR header. A segment can represent any
instruction, topological or service-based. SR allows to enforce a
flow through any topological path and service chain while maintaining
per-flow state only at the ingress node of the SR domain.
IGP protocols have been extended to advertise the segments. Because
of IGP's propagation scope limitation, it is not suited for IGP to
signal paths that span across AS borders. This document introduces
extensions of PCEP-LS to solve the problem without the similar
limitation.
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 3, 2017.
Li, et al. Expires May 3, 2017 [Page 1]
Internet-DrafPCEP Link-State extensions for Segment Routing October 2016
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
(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 . . . . . . . . . . . . . . . . . . . . . . . . 2
2. PCEP extensions for Segment Routing . . . . . . . . . . . . . 3
2.1. Node Attribute TLVs . . . . . . . . . . . . . . . . . . . 3
2.2. Link Attribute TLVs . . . . . . . . . . . . . . . . . . . 3
2.3. Prefix Attribute TLVs . . . . . . . . . . . . . . . . . . 4
3. Operational Considerations . . . . . . . . . . . . . . . . . 4
3.1. Segment Routing report . . . . . . . . . . . . . . . . . 4
3.2. Tunnel Segment Identifier . . . . . . . . . . . . . . . . 4
4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 4
5. Security Considerations . . . . . . . . . . . . . . . . . . . 4
6. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 4
7. References . . . . . . . . . . . . . . . . . . . . . . . . . 5
7.1. Normative References . . . . . . . . . . . . . . . . . . 5
7.2. Informative References . . . . . . . . . . . . . . . . . 5
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 5
1. Introduction
Segment Routing [I-D.ietf-spring-segment-routing] leverages source
routing. A node steers a packet through a controlled set of
instructions, called segments, by prepending the packet with an SR
header. A segment can represent any instruction, topological or
service-based. SR allows to enforce a flow through any topological
path and service chain while maintaining per-flow state only at the
ingress node of the SR domain.
IGP protocols have been extended to advertise the segments. Because
of IGP's propagation scope limitation, it is not suited for IGP to
signal paths that span across AS borders.
Li, et al. Expires May 3, 2017 [Page 2]
Internet-DrafPCEP Link-State extensions for Segment Routing October 2016
In order to fulfill the need for applications that require visibility
of SR paths across IGP areas or even across ASes, this document
defines extensions for the mechanism introduced in
[I-D.dhodylee-pce-pcep-ls] to propagate SR information in those
scenarios that have no IGP SR extension or BGP-LS running.
2. PCEP extensions for Segment Routing
PCEP-LS [I-D.dhodylee-pce-pcep-ls] introduces new message type and
new object to accommodate link-state information in PCEP. This
document defines new additional TLVs to map segment routing
information. The value portion of these new TLVs can reuse the
structure defined in [I-D.ietf-isis-segment-routing-extensions].
2.1. Node Attribute TLVs
Some new optional, non-transitive node attribute TLVs are defined for
carrying segment routing information and are listed below:
+--------------+-----------------------+----------+-----------------------+
|TLV Code Point| Description | Length | Value defined |
+--------------+-----------------------+----------+-----------------------+
| TBD1 | SID/Label Binding | variable | [ISIS-SR]#section2.4 |
+--------------+-----------------------+----------+-----------------------+
| TBD2 | SR-Capabilities | variable | [ISIS-SR]#section3.1 |
+--------------+-----------------------+----------+-----------------------+
| TBD3 | SR-Algorithm | variable | [ISIS-SR]#section3.2 |
+--------------+-----------------------+----------+-----------------------+
[ISIS-SR]: https://datatracker.ietf.org/doc/draft-ietf-isis-segment-
routing-extensions/
Table 1: Node Attribute TLVs
2.2. Link Attribute TLVs
Some new optional, non-transitive link attribute TLVs are defined for
carrying segment routing information and are listed below:
+--------------+-----------------------+----------+-----------------------+
|TLV Code Point| Description | Length | Value defined |
+--------------+-----------------------+----------+-----------------------+
| TBD4 | Adjacency Segment | variable | [ISIS-SR]#section2.2.1|
+--------------+-----------------------+----------+-----------------------+
| TBD5 | LAN Adjacency Segment | variable | [ISIS-SR]#section2.2.2|
+--------------+-----------------------+----------+-----------------------+
| TBD6 | Tunnel Segment | variable | |
+--------------+-----------------------+----------+-----------------------+
Li, et al. Expires May 3, 2017 [Page 3]
Internet-DrafPCEP Link-State extensions for Segment Routing October 2016
[ISIS-SR]: https://datatracker.ietf.org/doc/draft-ietf-isis-segment-
routing-extensions/
Table 2: Link Attribute TLVs
2.3. Prefix Attribute TLVs
A new optional, non-transitive link attribute TLVs are defined for
carrying segment routing information and are listed below:
+--------------+-----------------------+----------+-----------------------+
|TLV Code Point| Description | Length | Value defined |
+--------------+-----------------------+----------+-----------------------+
| TBD7 | Prefix Segment | variable | [ISIS-SR]#section2.1.2|
+--------------+-----------------------+----------+-----------------------+
[ISIS-SR]: https://datatracker.ietf.org/doc/draft-ietf-isis-segment-
routing-extensions/
Table 3: Prefix Attribute TLVs
3. Operational Considerations
3.1. Segment Routing report
The procedure for segment routing information reporting from PCC to
PCE will follow those defined in [I-D.dhodylee-pce-pcep-ls].
3.2. Tunnel Segment Identifier
Tunnel Segment introduced in [I-D.li-spring-tunnel-segment] is used
to identify a tunnel of any kind in a segment routing network. It is
originated by the tunnel ingress node and one SID is allocated and
attached to it either locally or globally.
4. IANA Considerations
TBD.
5. Security Considerations
TBD.
6. Acknowledgements
TBD.
Li, et al. Expires May 3, 2017 [Page 4]
Internet-DrafPCEP Link-State extensions for Segment Routing October 2016
7. References
7.1. Normative References
[I-D.dhodylee-pce-pcep-ls]
Dhody, D., Lee, Y., and D. Ceccarelli, "PCEP Extension for
Distribution of Link-State and TE Information.", draft-
dhodylee-pce-pcep-ls-06 (work in progress), September
2016.
[I-D.ietf-isis-segment-routing-extensions]
Previdi, S., Filsfils, C., Bashandy, A., Gredler, H.,
Litkowski, S., Decraene, B., and j. jefftant@gmail.com,
"IS-IS Extensions for Segment Routing", draft-ietf-isis-
segment-routing-extensions-08 (work in progress), October
2016.
[I-D.ietf-spring-segment-routing]
Filsfils, C., Previdi, S., Decraene, B., Litkowski, S.,
and R. Shakir, "Segment Routing Architecture", draft-ietf-
spring-segment-routing-09 (work in progress), July 2016.
[I-D.li-spring-tunnel-segment]
Li, Z. and N. Wu, "Tunnel Segment in Segment Routing",
draft-li-spring-tunnel-segment-01 (work in progress),
March 2016.
[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>.
7.2. Informative References
[RFC5440] Vasseur, JP., Ed. and JL. Le Roux, Ed., "Path Computation
Element (PCE) Communication Protocol (PCEP)", RFC 5440,
DOI 10.17487/RFC5440, March 2009,
<http://www.rfc-editor.org/info/rfc5440>.
Authors' Addresses
Zhenbin Li
Huawei Technologies
Huawei Bld., No.156 Beiqing Rd.
Beijing 100095
China
Email: lizhenbin@huawei.com
Li, et al. Expires May 3, 2017 [Page 5]
Internet-DrafPCEP Link-State extensions for Segment Routing October 2016
Xia Chen
Huawei Technologies
Huawei Bld., No.156 Beiqing Rd.
Beijing 100095
China
Email: jescia.chenxia@huawei.com
Nan Wu
Huawei Technologies
Huawei Bld., No.156 Beiqing Rd.
Beijing 100095
China
Email: eric.wu@huawei.com
Li, et al. Expires May 3, 2017 [Page 6]
