< draft-krishnan-6man-sids-00.txt   draft-ietf-6man-sids-00.txt >
6man S. Krishnan 6man S. Krishnan
Internet-Draft Kaloom Internet-Draft Cisco
Intended status: Informational February 10, 2022 Intended status: Informational 14 April 2022
Expires: August 14, 2022 Expires: 16 October 2022
Segment Identifiers in SRv6 Segment Identifiers in SRv6
draft-krishnan-6man-sids-00 draft-ietf-6man-sids-00
Abstract Abstract
The data plane for Segment Routing over IPv6 (SRv6) [RFC8754] is The data plane for Segment Routing over IPv6 (SRv6) [RFC8754] is
built using IPv6 as the underlying forwarding plane. Due to this built using IPv6 as the underlying forwarding plane. Due to this
underlying use of IPv6, Segment Identifiers (SIDs) used by SRv6 can underlying use of IPv6, Segment Identifiers (SIDs) used by SRv6 can
resemble IPv6 addresses and behave like them [RFC8754][RFC8986] while resemble IPv6 addresses and behave like them [RFC8754][RFC8986] while
exhibiting slightly different behaviors in some situations. This exhibiting slightly different behaviors in some situations. This
document intends to explore the characteristics of SRv6 SIDs and to document intends to explore the characteristics of SRv6 SIDs and to
clarify the relationship of SRv6 SIDs to the IPv6 Addressing clarify the relationship of SRv6 SIDs to the IPv6 Addressing
skipping to change at page 1, line 37 skipping to change at page 1, line 37
Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet- working documents as Internet-Drafts. The list of current Internet-
Drafts is at https://datatracker.ietf.org/drafts/current/. Drafts is at https://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress." material or to cite them other than as "work in progress."
This Internet-Draft will expire on August 14, 2022. This Internet-Draft will expire on 16 October 2022.
Copyright Notice Copyright Notice
Copyright (c) 2022 IETF Trust and the persons identified as the Copyright (c) 2022 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents Provisions Relating to IETF Documents (https://trustee.ietf.org/
(https://trustee.ietf.org/license-info) in effect on the date of license-info) in effect on the date of publication of this document.
publication of this document. Please review these documents Please review these documents carefully, as they describe your rights
carefully, as they describe your rights and restrictions with respect and restrictions with respect to this document. Code Components
to this document. Code Components extracted from this document must extracted from this document must include Revised BSD License text as
include Simplified BSD License text as described in Section 4.e of described in Section 4.e of the Trust Legal Provisions and are
the Trust Legal Provisions and are provided without warranty as provided without warranty as described in the Revised BSD License.
described in the Simplified BSD License.
Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 2 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 2
3. SRv6 SIDs and the IPv6 addressing architecture . . . . . . . 3 3. SRv6 SIDs and the IPv6 addressing architecture . . . . . . . 3
4. Special Considerations for Compressed SIDs . . . . . . . . . 4 4. Special Considerations for Compressed SIDs . . . . . . . . . 4
4.1. Open Issues to be Addressed with C-SIDs . . . . . . . . . 4 4.1. Open Issues to be Addressed with C-SIDs . . . . . . . . . 5
4.2. Applicability to other forms of compressed SIDs . . . . . 5 4.2. Applicability to other forms of compressed SIDs . . . . . 5
5. Allocation of a Global Unicast Prefix for SIDs . . . . . . . 5 5. Allocation of a Global Unicast Prefix for SIDs . . . . . . . 5
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 6 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 6
7. Security Considerations . . . . . . . . . . . . . . . . . . . 6 7. Security Considerations . . . . . . . . . . . . . . . . . . . 6
8. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 6 8. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 6
9. References . . . . . . . . . . . . . . . . . . . . . . . . . 6 9. References . . . . . . . . . . . . . . . . . . . . . . . . . 6
9.1. Normative References . . . . . . . . . . . . . . . . . . 6 9.1. Normative References . . . . . . . . . . . . . . . . . . 6
9.2. Informative References . . . . . . . . . . . . . . . . . 7 9.2. Informative References . . . . . . . . . . . . . . . . . 7
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 7 Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 8
1. Introduction 1. Introduction
Segment Routing over IPv6 (SRv6) [RFC8754] uses IPv6 as the Segment Routing over IPv6 (SRv6) [RFC8754] uses IPv6 as the
underlying data plane. In SRv6, SR source nodes initiate packets underlying data plane. In SRv6, SR source nodes initiate packets
with a segment in the Destination Address of the IPv6 header, and SR with a segment in the Destination Address of the IPv6 header, and SR
segment endpoint nodes that process a local segment present the segment endpoint nodes that process a local segment present the
Destination Address of an IPv6 header. Thus Segment Identifiers Destination Address of an IPv6 header. Thus Segment Identifiers
(SIDs) in SRv6 can and do appear in the Destination Address field of (SIDs) in SRv6 can and do appear in the Destination Address field of
IPv6 datagrams by design. IPv6 datagrams by design.
2. Terminology 2. Terminology
The following terms are used as defined in [RFC8402]. The following terms are used as defined in [RFC8402].
o Segment Routing (SR) * Segment Routing (SR)
o SR Domain
o Segment * SR Domain
o Segment ID (SID) * Segment
o SRv6 * Segment ID (SID)
* SRv6
o SRv6 SID * SRv6 SID
o SR Policy. * SR Policy.
The following terms are used as defined in [RFC8754]. The following terms are used as defined in [RFC8754].
o Segment Routing Header (SRH) * Segment Routing Header (SRH)
o SR Source Node * SR Source Node
o Transit Node * Transit Node
o SR Segment Endpoint Node * SR Segment Endpoint Node
o Reduced SRH * Reduced SRH
o Segments Left * Segments Left
o Last Entry * Last Entry
3. SRv6 SIDs and the IPv6 addressing architecture 3. SRv6 SIDs and the IPv6 addressing architecture
[RFC8754] defines the Segment List of the SRH as a contiguous array [RFC8754] defines the Segment List of the SRH as a contiguous array
of 128-bit IPv6 addresses, and that each of the elements in this list of 128-bit IPv6 addresses, and that each of the elements in this list
are SIDs. But all of these elements are not necessarily made equal. are SIDs. But all of these elements are not necessarily made equal.
Some of these elements may represent a local interface as described Some of these elements may represent a local interface as described
in Section 4.3 of [RFC8754] as "A FIB entry that represents a local in Section 4.3 of [RFC8754] as "A FIB entry that represents a local
interface, not locally instantiated as an SRv6 SID". From this it interface, not locally instantiated as an SRv6 SID". From this it
follows that all the SIDs that appear in the SRH are not SRv6 SIDs as follows that all the SIDs that appear in the SRH are not SRv6 SIDs as
skipping to change at page 5, line 5 skipping to change at page 5, line 10
the SRv6 SIDs are being treated simply as routing prefixes on transit the SRv6 SIDs are being treated simply as routing prefixes on transit
nodes this does not constitute a modification to the IPv6 data plane nodes this does not constitute a modification to the IPv6 data plane
on such transit nodes and any changes are restricted to SR aware on such transit nodes and any changes are restricted to SR aware
nodes. nodes.
4.1. Open Issues to be Addressed with C-SIDs 4.1. Open Issues to be Addressed with C-SIDs
There are a few issues that need to be addressed in the C-SID draft There are a few issues that need to be addressed in the C-SID draft
prior to its publication as RFC: prior to its publication as RFC:
o This draft needs to provide an updated definition for the * This draft needs to provide an updated definition for the
SegmentsLeft field of the SRH since the current definition in SegmentsLeft field of the SRH since the current definition in
[RFC8754][RFC8200] no longer holds true in the presence of C-SIDs. [RFC8754][RFC8200] no longer holds true in the presence of C-SIDs.
o In some cases it is possible that the SR policy can be expressed * In some cases it is possible that the SR policy can be expressed
purely with C-SIDs without requiring an SRH. In this case, to purely with C-SIDs without requiring an SRH. In this case, to
allow the SR domain to fail closed, some form of filtering based allow the SR domain to fail closed, some form of filtering based
on the LOC part of the SRv6 SID is required as relying purely on on the LOC part of the SRv6 SID is required as relying purely on
the presence of an SRH will not be sufficient. the presence of an SRH will not be sufficient.
o The use of C-SIDs might cause some difficulty in troubleshooting * The use of C-SIDs might cause some difficulty in troubleshooting
error conditions signaled by ICMPv6. Section 5.4 of [RFC8754] error conditions signaled by ICMPv6. Section 5.4 of [RFC8754]
describes the ICMPv6 error processing that is required to be describes the ICMPv6 error processing that is required to be
performed on the SR Source Nodes to correlate packets since the performed on the SR Source Nodes to correlate packets since the
Destination Address field of the packet changes in flight. Destination Address field of the packet changes in flight.
Similar logic needs to be specified for SR Source Nodes that use Similar logic needs to be specified for SR Source Nodes that use
C-SIDs to determine the destination address for use by protocol- C-SIDs to determine the destination address for use by protocol-
error handlers. error handlers.
4.2. Applicability to other forms of compressed SIDs 4.2. Applicability to other forms of compressed SIDs
skipping to change at page 7, line 22 skipping to change at page 7, line 27
(SRv6) Network Programming", RFC 8986, (SRv6) Network Programming", RFC 8986,
DOI 10.17487/RFC8986, February 2021, DOI 10.17487/RFC8986, February 2021,
<https://www.rfc-editor.org/info/rfc8986>. <https://www.rfc-editor.org/info/rfc8986>.
9.2. Informative References 9.2. Informative References
[I-D.filsfilscheng-spring-srv6-srh-compression] [I-D.filsfilscheng-spring-srv6-srh-compression]
Cheng, W., Filsfils, C., Li, Z., Decraene, B., Cai, D., Cheng, W., Filsfils, C., Li, Z., Decraene, B., Cai, D.,
Voyer, D., Clad, F., Zadok, S., Guichard, J., Liu, A., Voyer, D., Clad, F., Zadok, S., Guichard, J., Liu, A.,
Raszuk, R., and C. Li, "Compressed SRv6 Segment List Raszuk, R., and C. Li, "Compressed SRv6 Segment List
Encoding in SRH", draft-filsfilscheng-spring-srv6-srh- Encoding in SRH", Work in Progress, Internet-Draft, draft-
compression-02 (work in progress), July 2021. filsfilscheng-spring-srv6-srh-compression-02, 28 July
2021, <https://www.ietf.org/archive/id/draft-
filsfilscheng-spring-srv6-srh-compression-02.txt>.
[I-D.ietf-spring-compression-analysis] [I-D.ietf-spring-compression-analysis]
Bonica, R., Cheng, W., Dukes, D., Henderickx, W., Li, C., Bonica, R., Cheng, W., Dukes, D., Henderickx, W., Li, C.,
Peng, S., and C. Xie, "Compressed SRv6 SID List Analysis", Peng, S., and C. Xie, "Compressed SRv6 SID List Analysis",
draft-ietf-spring-compression-analysis-00 (work in Work in Progress, Internet-Draft, draft-ietf-spring-
progress), September 2021. compression-analysis-00, 27 September 2021,
<https://www.ietf.org/archive/id/draft-ietf-spring-
compression-analysis-00.txt>.
[RFC6052] Bao, C., Huitema, C., Bagnulo, M., Boucadair, M., and X. [RFC6052] Bao, C., Huitema, C., Bagnulo, M., Boucadair, M., and X.
Li, "IPv6 Addressing of IPv4/IPv6 Translators", RFC 6052, Li, "IPv6 Addressing of IPv4/IPv6 Translators", RFC 6052,
DOI 10.17487/RFC6052, October 2010, DOI 10.17487/RFC6052, October 2010,
<https://www.rfc-editor.org/info/rfc6052>. <https://www.rfc-editor.org/info/rfc6052>.
[RFC6169] Krishnan, S., Thaler, D., and J. Hoagland, "Security [RFC6169] Krishnan, S., Thaler, D., and J. Hoagland, "Security
Concerns with IP Tunneling", RFC 6169, Concerns with IP Tunneling", RFC 6169,
DOI 10.17487/RFC6169, April 2011, DOI 10.17487/RFC6169, April 2011,
<https://www.rfc-editor.org/info/rfc6169>. <https://www.rfc-editor.org/info/rfc6169>.
[RFC7343] Laganier, J. and F. Dupont, "An IPv6 Prefix for Overlay [RFC7343] Laganier, J. and F. Dupont, "An IPv6 Prefix for Overlay
Routable Cryptographic Hash Identifiers Version 2 Routable Cryptographic Hash Identifiers Version 2
(ORCHIDv2)", RFC 7343, DOI 10.17487/RFC7343, September (ORCHIDv2)", RFC 7343, DOI 10.17487/RFC7343, September
2014, <https://www.rfc-editor.org/info/rfc7343>. 2014, <https://www.rfc-editor.org/info/rfc7343>.
Author's Address Author's Address
Suresh Krishnan Suresh Krishnan
Kaloom Cisco
Email: suresh.krishnan@gmail.com
Email: suresh@kaloom.com
 End of changes. 25 change blocks. 
37 lines changed or deleted 39 lines changed or added

This html diff was produced by rfcdiff 1.48. The latest version is available from http://tools.ietf.org/tools/rfcdiff/