Internet DRAFT - draft-previdi-isis-ipv6-prefix-sid
draft-previdi-isis-ipv6-prefix-sid
Network Working Group S. Previdi, Ed.
Internet-Draft L. Ginsberg
Intended status: Standards Track C. Filsfils
Expires: May 18, 2017 Cisco Systems, Inc.
November 14, 2016
Segment Routing IPv6 Prefix-SID
draft-previdi-isis-ipv6-prefix-sid-03
Abstract
This document defines the Segment Routing IPv6-Prefix-SID sub-TLV.
This new sub-TLV allows to specify which of the prefixes advertised
by a node are to be used as Segment Routing Identifiers (SID) for the
IPv6 data plane.
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 18, 2017.
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
Previdi, et al. Expires May 18, 2017 [Page 1]
Internet-Draft IPv6 Prefix-SID November 2016
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. IPv6 Prefix SID . . . . . . . . . . . . . . . . . . . . . . . 2
3. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 4
4. Security Considerations . . . . . . . . . . . . . . . . . . . 4
5. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 4
6. References . . . . . . . . . . . . . . . . . . . . . . . . . 4
6.1. Normative References . . . . . . . . . . . . . . . . . . 4
6.2. Informative References . . . . . . . . . . . . . . . . . 5
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 5
1. Introduction
With Segment Routing (SR)[I-D.ietf-spring-segment-routing], a node
steers a packet through an ordered list of instructions, called
segments. Segments are identified through Segment Identifiers (SIDs)
that are advertised by routing protocols. The IS-IS extensions for
SR information advertisement are defined in
[I-D.ietf-isis-segment-routing-extensions].
Segment Routing can be directly applied to the IPv6 data plane
through the use of the Segment Routing Header defined in
[I-D.ietf-6man-segment-routing-header].
When applied to the IPv6 data plane, the SID is represented by an
IPv6 address. This document defines a new IS-IS Prefix sub-TLV where
information related to the IPv6 address used as SR IPv6 SID is
conveyed.
2. IPv6 Prefix SID
When SR is applied to the IPv6 data plane, Segment Identifiers (SIDs)
are IPv6 addresses. In a router, it is desirable to identify which
of the local prefixes can be used as SIDs. Also, and in order to
provide the same functionalities defined in
[I-D.ietf-spring-segment-routing] and according to
[I-D.ietf-isis-segment-routing-extensions], a new sub-TLV is defined:
the IPv6-Prefix-SID sub-TLV.
Previdi, et al. Expires May 18, 2017 [Page 2]
Internet-Draft IPv6 Prefix-SID November 2016
The IPv6-Prefix-SID sub-TLV is attached to an IPv6 prefix advertised
by a node and MAY be present in any of the following TLVs:
TLV-236 (IPv6) defined in [RFC5308].
TLV-237 (MT-IPv6) defined in [RFC5120].
The IPv6-Prefix-SID sub-TLV is optional, MAY appear only once for a
given prefix and has the following format:
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 | Length | Flags |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Algorithm | //
+-+-+-+-+-+-+-+-+ Sub-TLVs //
// //
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
where:
Type: To be assigned by IANA (suggested value 5).
Length: 3 + length of sub-TLVs.
Flags: 2 octet field of flags. None of them is defined at this
stage.
Algorithm: as defined in
[I-D.ietf-isis-segment-routing-extensions].
Sub-TLVs: additional information encoded into the IPv6-Prefix-SID
Sub-TLV. Currently, no sub-TLVs are defined yet.
A prefix with an attached IPv6-Prefix-SID sub-TLV is defined as an
SR-IPv6 Prefix SID. If the prefix is to be used as a Node-SID
(according to [I-D.ietf-isis-segment-routing-extensions]) then the
following applies:
o The IPv6 prefix MUST be advertised with the IPv6-Prefix-SID sub-
TLV attached.
o The Extended Reachability Attribute Flags sub-TLV defined in
[RFC7794] MUST be attached to the prefix and the N-flag MUST be
set.
Previdi, et al. Expires May 18, 2017 [Page 3]
Internet-Draft IPv6 Prefix-SID November 2016
When a router has attached an IPv6-Prefix-SID sub-TLV to a prefix, it
implies that the router supports the Segment Routing Header (SRH,
defined in [I-D.ietf-6man-segment-routing-header] and its associated
procedures for packets destined to the advertised prefix.
A router receiving an IPv6-Prefix-SID from a remote node and with an
algorithm value that such remote node has not advertised in the SR-
Capability sub-TLV (as defined in
[I-D.ietf-isis-segment-routing-extensions]) MUST ignore the IPv6-
Prefix-SID sub-TLV.
3. IANA Considerations
This document makes the following registrations in the "sub-TLVs for
TLV 135, 235, 236 and 237" registry.
Type: TBD (suggested value 5)
Description: IPv6 Prefix Segment Identifier
TLV 135: no
TLV 235: no
TLV 236: yes
TLV 237: yes
Reference: This document (Section 2)
4. Security Considerations
This document doesn't introduce new security considerations.
5. Acknowledgements
The authors would like to thank Nagendra Kumar for his review of this
document.
6. References
6.1. 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>.
Previdi, et al. Expires May 18, 2017 [Page 4]
Internet-Draft IPv6 Prefix-SID November 2016
[RFC5120] Przygienda, T., Shen, N., and N. Sheth, "M-ISIS: Multi
Topology (MT) Routing in Intermediate System to
Intermediate Systems (IS-ISs)", RFC 5120,
DOI 10.17487/RFC5120, February 2008,
<http://www.rfc-editor.org/info/rfc5120>.
[RFC5308] Hopps, C., "Routing IPv6 with IS-IS", RFC 5308,
DOI 10.17487/RFC5308, October 2008,
<http://www.rfc-editor.org/info/rfc5308>.
[RFC7794] Ginsberg, L., Ed., Decraene, B., Previdi, S., Xu, X., and
U. Chunduri, "IS-IS Prefix Attributes for Extended IPv4
and IPv6 Reachability", RFC 7794, DOI 10.17487/RFC7794,
March 2016, <http://www.rfc-editor.org/info/rfc7794>.
6.2. Informative References
[I-D.ietf-6man-segment-routing-header]
Previdi, S., Filsfils, C., Field, B., Leung, I., Linkova,
J., Aries, E., Kosugi, T., Vyncke, E., and D. Lebrun,
"IPv6 Segment Routing Header (SRH)", draft-ietf-6man-
segment-routing-header-02 (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-09 (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.
Authors' Addresses
Stefano Previdi (editor)
Cisco Systems, Inc.
Via Del Serafico, 200
Rome 00142
Italy
Email: sprevidi@cisco.com
Previdi, et al. Expires May 18, 2017 [Page 5]
Internet-Draft IPv6 Prefix-SID November 2016
Les Ginsberg
Cisco Systems, Inc.
US
Email: ginsberg@cisco.com
Clarence Filsfils
Cisco Systems, Inc.
Brussels
BE
Email: cfilsfil@cisco.com
Previdi, et al. Expires May 18, 2017 [Page 6]
