Internet Engineering Task Force (IETF) T. Graf
Request for Comments: 9487 Swisscom
Category: Standards Track B. Claise
ISSN: 2070-1721 Huawei
P. Francois
INSA-Lyon
October
November 2023
Export of Segment Routing over IPv6 Information in IP Flow Information
Export (IPFIX)
Abstract
This document introduces new IP Flow Information Export (IPFIX)
Information Elements (IEs) to identify a set of information related
to Segment Routing over IPv6 (SRv6) related information such as data contained in a
Segment Routing Header (SRH), the SRv6 control plane, and the SRv6
Endpoint behavior that traffic is being forwarded with.
Status of This Memo
This is an Internet Standards Track document.
This document is a product of the Internet Engineering Task Force
(IETF). It represents the consensus of the IETF community. It has
received public review and has been approved for publication by the
Internet Engineering Steering Group (IESG). Further information on
Internet Standards is available in Section 2 of RFC 7841.
Information about the current status of this document, any errata,
and how to provide feedback on it may be obtained at
https://www.rfc-editor.org/info/rfc9487.
Copyright Notice
Copyright (c) 2023 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
(https://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 Revised BSD License text as described in Section 4.e of the
Trust Legal Provisions and are provided without warranty as described
in the Revised BSD License.
Table of Contents
1. Introduction
2. Terminology
3. New IPFIX IPv6 SRH Information Elements
4. Sample Use Cases
5. IANA Considerations
5.1. New IPFIX IPv6 SRH Information Elements Registry
5.1.1. srhFlagsIPv6
5.1.2. srhTagIPv6
5.1.3. srhSegmentIPv6
5.1.4. srhActiveSegmentIPv6
5.1.5. srhSegmentIPv6BasicList
5.1.6. srhSegmentIPv6ListSection
5.1.7. srhSegmentsIPv6Left
5.1.8. srhIPv6Section
5.1.9. srhIPv6ActiveSegmentType
5.1.10. srhSegmentIPv6LocatorLength
5.1.11. srhSegmentIPv6EndpointBehavior
5.2. New IPFIX IPv6 SRH Segment Type (Value 500) Subregistry
6. Operational Considerations
6.1. SRv6 Segment List
6.2. Compressed SRv6 Segment List Decomposition
7. Security Considerations
8. References
8.1. Normative References
8.2. Informative References
Appendix A. IPFIX Encoding Examples
A.1. Three Observed SRH Headers and Their Routing Protocols
A.1.1. Template Record and Data Set with Segment Basic List
A.1.2. Template Record and Data Set with Segment List Section
A.1.3. Template Record and Data Set with SRH Section
A.2. Options Template Record and Data Set for SRv6 Segment
Endpoint Behavior and Locator Length
Acknowledgements
Authors' Addresses
1. Introduction
A dedicated Routing Extension Header, called "Segment Routing Header
(SRH)", is defined in [RFC8754] for use of Segment Routing (SR) over IPv6
(SRv6) data plane.
Also, three routing protocol extensions, OSPFv3 [OSPFV3-SRV6-EXT],
IS-IS [RFC9352], and BGP Prefix Segment Identifiers (Prefix-SIDs)
[RFC8669]; the Path Computation Element Communication Protocol (PCEP)
Extension [SR-IPV6]; [PCEP-SRV6-EXT]; and the Segment Routing Policy [RFC9256]
are defined to propagate Segment Identifiers (SIDs).
SRv6 Segment Endpoint behaviors describe how packets should be
processed by SRv6 Segment Endpoint Nodes. Such behaviors are defined
in [RFC8986].
This document specifies eleven new IPFIX Information Elements (IEs)
and one new subregistry within the "IPFIX Information Elements"
registry [RFC7012], for SRv6 purposes.
These IEs are used to export the SRv6 active segment and its control
plane protocol, the SRv6 Segment List, the next SRv6 node and its
type, and the numbers of SRv6 segments left.
Some examples are provided in Appendix A.
2. Terminology
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in
BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all
capitals, as shown here.
This document makes use of the terms defined in [RFC7011], [RFC8402],
and [RFC8754].
The following terms are used as defined in [RFC7011]:
* IPFIX
* IPFIX Information Elements
* Template
* Template Record
* Options Template
* Options Template Record
* Data Record
* Data Set
The following terms are used as defined in [RFC8402]:
* Segment Routing (SR)
* Segment
* Segment List
* Active Segment
* Segment Identifier (SID)
* SRv6
* SRv6 SID
The following terms are used as defined in [RFC8754]:
* Segment Routing Header (SRH)
* SR Source Node
* Transit Node
* SR Segment Endpoint Node
* Reduced SRH
* Segments Left
* Last Entry
3. New IPFIX IPv6 SRH Information Elements
This section specifies the new IPFIX IPv6 SRH IEs.
srhFlagsIPv6
The 8-bit flags Flags field defined in the SRH (Section 2 of [RFC8754]).
srhTagIPv6
The 16-bit tag Tag field defined in the SRH (Section 2 of [RFC8754]).
A tag is used to mark a packet as part of a class or group of
packets sharing the same set of properties.
srhSegmentIPv6
The 128-bit IPv6 address that represents an SRv6 segment.
srhActiveSegmentIPv6
The 128-bit IPv6 address that represents the active SRv6 segment.
srhSegmentIPv6BasicList
Ordered
The ordered basicList [RFC6313] of zero or more 128-bit IPv6
addresses in the SRH that represents the SRv6 Segment List. As
specified in Section 2 of [RFC8754], the Segment List is encoded
starting from the last segment of the SR Policy. That is, the
first element of the Segment List (Segment List[0]) contains the
last segment of the SR Policy, the second element contains the
penultimate segment of the SR Policy, and so on.
srhSegmentIPv6ListSection
The SRH Segment List as defined in Section 2 of [RFC8754] as a
series of octets in IPFIX.
srhSegmentsIPv6Left
The 8-bit unsigned integer defining that defines the number of segments
remaining to reach the end of the Segment List from the SRH, as
specified by the "Segments Left" field in Section 4.4 of [RFC8200]
and as mentioned part of in the SRH in part of Section 2 of [RFC8754].
srhIPv6Section
Exposes the
The SRH and its TLVs as specified in Section 2 of [RFC8754] as a
series of octets in IPFIX.
srhIPv6ActiveSegmentType
Designator
The designator of the routing protocol or PCEP extension where the
active SRv6 segment has been learned from.
srhSegmentIPv6LocatorLength
The length of the SRH segment IPv6 locator length specified as the number
of significant bits. Together with srhSegmentIPv6, it enables the
calculation of the SRv6 Locator.
srhSegmentIPv6EndpointBehavior
The 16-bit unsigned integer that represents an SRv6 Endpoint
behavior as per Section 4 of [RFC8986].
Note that the srhSegmentIPv6, srhSegmentIPv6LocatorLength, and
srhSegmentIPv6EndpointBehavior IPFIX IEs are generic fields to be
used in the context of IPFIX Options Templates or IPFIX Structured
Data [RFC6313].
4. Sample Use Cases
The IPFIX IEs srhSegmentIPv6BasicList (496) or alternatively
srhSegmentIPv6ListSection (497), srhActiveSegmentIPv6 (495),
srhSegmentsIPv6Left (498), srhIPv6ActiveSegmentType (500), and
forwardingStatus (89) [RFC7270] [IANA-IPFIX] as well as some existing
counter information [IANA-IPFIX] provide answers to the following
questions (amongst others):
* How many packets steered with an SR policy are forwarded or
dropped using SRv6 in a network?
* If dropped, for which reasons?
* What is the current active segment and its associated control
plane protocol?
* What is the SRv6 Segment List?
* What is the next SRv6 node and its type?
* How many SRv6 segments are left?
5. IANA Considerations
5.1. New IPFIX IPv6 SRH Information Elements Registry
IANA has added the following new IEs to the "IPFIX Information
Elements" registry [RFC7012] at [IANA-IPFIX]:
+===========+================================+
| ElementID | Name |
+===========+================================+
| 492 | srhFlagsIPv6 |
+-----------+--------------------------------+
| 493 | srhTagIPv6 |
+-----------+--------------------------------+
| 494 | srhSegmentIPv6 |
+-----------+--------------------------------+
| 495 | srhActiveSegmentIPv6 |
+-----------+--------------------------------+
| 496 | srhSegmentIPv6BasicList |
+-----------+--------------------------------+
| 497 | srhSegmentIPv6ListSection |
+-----------+--------------------------------+
| 498 | srhSegmentsIPv6Left |
+-----------+--------------------------------+
| 499 | srhIPv6Section |
+-----------+--------------------------------+
| 500 | srhIPv6ActiveSegmentType |
+-----------+--------------------------------+
| 501 | srhSegmentIPv6LocatorLength |
+-----------+--------------------------------+
| 502 | srhSegmentIPv6EndpointBehavior |
+-----------+--------------------------------+
Table 1: IPFIX Information Elements Registry
5.1.1. srhFlagsIPv6
Name: srhFlagsIPv6
ElementID: 492
Name: srhFlagsIPv6
Abstract Data Type: unsigned8
Data Type Semantics: flags
Description: The 8-bit flags Flags field defined in the SRH (Section 2 of
[RFC8754]). Assigned flags and their meanings are provided in the
"Segment Routing Header Flags" IANA registry.
Abstract Data Type: unsigned8
Data Type Semantics: flags
Additional Information: See the assignments in the "Segment Routing
Header Flags" registry at <https://www.iana.org/assignments/
ipv6-parameters>. See also [RFC8754] for the SRH specification.
Reference: RFC 9487
5.1.2. srhTagIPv6
Name: srhTagIPv6
ElementID: 493
Name: srhTagIPv6
Abstract Data Type: unsigned16
Data Type Semantics: identifier
Description: The 16-bit tag Tag field defined in the SRH (Section 2 of
[RFC8754]). A tag is used to mark a packet as part of a class or
group of packets sharing the same set of properties.
Abstract Data Type: unsigned16
Data Type Semantics: identifier
Additional Information: See Section 2 of [RFC8754] for more details
about the tag. Tag.
Reference: RFC 9487
5.1.3. srhSegmentIPv6
Name: srhSegmentIPv6
ElementID: 494
Name: srhSegmentIPv6
Abstract Data Type: ipv6Address
Data Type Semantics: default
Description: The 128-bit IPv6 address that represents an SRv6
segment.
Abstract Data Type: ipv6Address
Data Type Semantics: default
Additional Information: Specified in Section 1 of [RFC8402] and
mentioned in "Segment List" in Section 2 of [RFC8754].
Reference: RFC 9487
5.1.4. srhActiveSegmentIPv6
Name: srhActiveSegmentIPv6
ElementID: 495
Name: srhActiveSegmentIPv6
Abstract Data Type: ipv6Address
Data Type Semantics: default
Description: The 128-bit IPv6 address that represents the active
SRv6 segment.
Abstract Data Type: ipv6Address
Data Type Semantics: default
Additional Information: See Section 2 of [RFC8402] for the
definition of "active segment".
Reference: RFC 9487
5.1.5. srhSegmentIPv6BasicList
Name: srhSegmentIPv6BasicList
ElementID: 496
Name: srhSegmentIPv6BasicList
Abstract Data Type: basicList
Data Type Semantics: list
Description: The ordered basicList [RFC6313] of zero or more 128-bit
IPv6 addresses in the SRH that represents the SRv6 Segment List.
As specified in Section 2 of [RFC8754], the Segment List is
encoded starting from the last segment of the SR Policy. That is,
the first element of the Segment List (Segment List[0]) contains
the last segment of the SR Policy, the second element contains the
penultimate segment of the SR Policy, and so on.
Abstract Data Type: basicList
Data Type Semantics: list
Additional Information: See Section 2 of [RFC8754] for more details
about the SRv6 Segment List.
Reference: RFC 9487
5.1.6. srhSegmentIPv6ListSection
Name: srhSegmentIPv6ListSection
ElementID: 497
Name: srhSegmentIPv6ListSection
Abstract Data Type: octetArray
Data Type Semantics: default
Description: The SRH SRv6 Segment List as defined in Section 2 of
[RFC8754] as a series of octets in IPFIX.
Abstract Data Type: octetArray
Data Type Semantics: default
Additional Information: See Section 2 of [RFC8754] for more details
about the SRv6 Segment List.
Reference: RFC 9487
5.1.7. srhSegmentsIPv6Left
Name: srhSegmentsIPv6Left
ElementID: 498
Name: srhSegmentsIPv6Left
Abstract Data Type: unsigned8
Data Type Semantics: quantity
Description: The 8-bit unsigned integer defining the number of
segments remaining to reach the end of the Segment List in from the
SRH.
Abstract Data Type: unsigned8
Data Type Semantics: quantity
Additional Information: Specified by the "Segments Left" field in
Section 4.4 of [RFC8200] and mentioned in Section 2 of [RFC8754].
Reference: RFC 9487
5.1.8. srhIPv6Section
Name: srhIPv6Section
ElementID: 499
Name: srhIPv6Section
Abstract Data Type: octetArray
Data Type Semantics: default
Description: The SRH and its TLVs as defined in Section 2 of
[RFC8754] as a series of octets in IPFIX.
Abstract Data Type: octetArray
Data Type Semantics: default
Additional Information: See Section 2 of [RFC8754] for more details
about the structure of an SRH.
Reference: RFC 9487
5.1.9. srhIPv6ActiveSegmentType
Name: srhIPv6ActiveSegmentType
ElementID: 500
Name: srhIPv6ActiveSegmentType
Abstract Data Type: unsigned8
Data Type Semantics: identifier
Description: The designator of the routing protocol or PCEP
extension from where the active SRv6 segment has been learned from.
Values for this Information Element are listed in the "IPFIX IPv6
SRH Segment Type (Value 500)" subregistry.
Abstract Data Type: unsigned8
Data Type Semantics: identifier
Additional Information: See the assigned types in the "IPFIX IPv6
SRH Segment (Value 500)" registry at
<https://www.iana.org/assignments/ipfix>.
Reference: RFC 9487
5.1.10. srhSegmentIPv6LocatorLength
Name: srhSegmentIPv6LocatorLength
ElementID: 501
Name: srhSegmentIPv6LocatorLength
Data Type Semantics: default
Description: The length of the SRH segment IPv6 locator length specified as
the number of significant bits. Together with srhSegmentIPv6, it
enables the calculation of the SRv6 Locator.
Abstract Data Type: unsigned8
Data Type Semantics: default
Additional Information: See Section 3.1 of [RFC8986] for more
details about the SID format.
Reference: RFC 9487
5.1.11. srhSegmentIPv6EndpointBehavior
Name: srhSegmentIPv6EndpointBehavior
ElementID: 502
Name: srhSegmentIPv6EndpointBehavior
Abstract Data Type: unsigned16
Data Type Semantics: identifier
Description: The 16-bit unsigned integer that represents an SRv6
Endpoint behavior as per Section 4 of [RFC8986]. Assigned values
and their meanings are provided in the "SRv6 Endpoint Behaviors"
registry.
Abstract Data Type: unsigned16
Data Type Semantics: identifier
Additional Information: See the assigned behaviors in the "SRv6
Endpoint Behaviors" registry at <https://www.iana.org/assignments/
segment-routing>. See Section 4 of [RFC8986] for more details
about the processing of endpoint behaviors.
Reference: RFC 9487
5.2. New IPFIX IPv6 SRH Segment Type (Value 500) Subregistry
IANA has created a new subregistry called "IPFIX IPv6 SRH Segment
Type (Value 500)" under the "IPFIX Information Elements" registry
[RFC7012] at [IANA-IPFIX].
The allocation policy of this new subregistry is Expert Review
(Section 4.5 of [RFC8126]).
The designated experts for this registry should be familiar with SRH.
The guidelines that are being followed by the designated experts for
the "IPFIX Information Elements" registry should be followed for this
subregistry. In particular, criteria that should be applied by the
designated experts include determining whether the proposed
registration duplicates existing entries and whether the registration
description is clear and fits the purpose of this registry. Within
the review period, the designated experts will either approve or deny
the registration request, communicating this decision to IANA.
Denials should include an explanation and, if applicable, suggestions
as to how to make the request successful.
Initial values in the registry are defined in Table 2.
+=======+==========================+=============================+
| Value | Description | Reference |
+=======+==========================+=============================+
| 0 | Unknown | RFC 9487 |
+-------+--------------------------+-----------------------------+
| 1 | Segment Routing Policy | RFC 9487, [RFC9256] |
+-------+--------------------------+-----------------------------+
| 2 | Path Computation Element | RFC 9487, [SR-IPV6] [PCEP-SRV6-EXT] |
+-------+--------------------------+-----------------------------+
| 3 | OSPFv3 Segment Routing | RFC 9487, [OSPFV3-SRV6-EXT] |
+-------+--------------------------+-----------------------------+
| 4 | IS-IS Segment Routing | RFC 9487, [RFC9352] |
+-------+--------------------------+-----------------------------+
| 5 | BGP Segment Routing | RFC 9487, [RFC8669] |
| | Prefix-SID | |
+-------+--------------------------+-----------------------------+
Table 2: IPFIX IPv6 SRH Segment Type (Value 500) Subregistry
6. Operational Considerations
6.1. SRv6 Segment List
The zero or more 128-bit IPv6 addresses in the SRH [RFC8754] can be
exported in two different ways, with two different IPFIX IEs:
* srhSegmentIPv6BasicList
* srhSegmentIPv6ListSection
The srhSegmentIPv6BasicList encodes the SRv6 Segment List with a
basicList, specified in the IPFIX Structured Data [RFC6313]. This
encoding is an advantage for data collection since the different IPv6
addresses are already structured as a list, without the need of post-
processing. However, this method requires some extra processing on
the exporter to realize the BasicList basicList data mapping.
The srhSegmentIPv6ListSection, on the other hand, encodes the list of
IPv6 addresses as an octetArray. This doesn't impose any data flow
manipulation on the exporter, facilitating the immediate export.
However, the data collection MUST be able to decode the IPv6
addresses according to the SR specifications. Compared to the
srhSegmentIPv6BasicList, the srhSegmentIPv6ListSection flow records
length is slightly reduced.
It is not expected that an exporter would support both
srhSegmentIPv6BasicList and srhSegmentIPv6ListSection at the same
time.
6.2. Compressed SRv6 Segment List Decomposition
The SRv6 Segment List in the IPFIX IEs srhSegmentIPv6BasicList,
srhSegmentIPv6ListSection, and destinationIPv6Address could contain
compressed-SID containers as described in [SRV6-SRH-COM]. The SR
Endpoint Flavors, as described in Section 4 of [SRV6-SRH-COM], define
new flavors for SID Endpoint behaviors and determine wherever the
Segment List encoding is compressed, along with the flavor. The SID
Locator, as described in Section 3.1 of [RFC8986], determines the
common most significant bits. By using described information from
srhSegmentIPv6EndpointBehavior and srhSegmentIPv6LocatorLength, the
compressed-SID containers can be decoded at the data collection.
7. Security Considerations
There are no additional security considerations regarding allocation
of these new IPFIX IEs compared to [RFC7012].
The IEs described in this document export provider plane data metrics
on how packets are being forwarded within an SRv6 network.
Applications and operators using the IEs described in this document
must evaluate the sensitivity of this information in their
implementation context and apply the data-at-rest storage guidance in
Section 11.8 of [RFC7011] as appropriate.
8. References
8.1. 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,
<https://www.rfc-editor.org/info/rfc2119>.
[RFC6313] Claise, B., Dhandapani, G., Aitken, P., and S. Yates,
"Export of Structured Data in IP Flow Information Export
(IPFIX)", RFC 6313, DOI 10.17487/RFC6313, July 2011,
<https://www.rfc-editor.org/info/rfc6313>.
[RFC7011] Claise, B., Ed., Trammell, B., Ed., and P. Aitken,
"Specification of the IP Flow Information Export (IPFIX)
Protocol for the Exchange of Flow Information", STD 77,
RFC 7011, DOI 10.17487/RFC7011, September 2013,
<https://www.rfc-editor.org/info/rfc7011>.
[RFC7012] Claise, B., Ed. and B. Trammell, Ed., "Information Model
for IP Flow Information Export (IPFIX)", RFC 7012,
DOI 10.17487/RFC7012, September 2013,
<https://www.rfc-editor.org/info/rfc7012>.
[RFC8126] Cotton, M., Leiba, B., and T. Narten, "Guidelines for
Writing an IANA Considerations Section in RFCs", BCP 26,
RFC 8126, DOI 10.17487/RFC8126, June 2017,
<https://www.rfc-editor.org/info/rfc8126>.
[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
May 2017, <https://www.rfc-editor.org/info/rfc8174>.
[RFC8200] Deering, S. and R. Hinden, "Internet Protocol, Version 6
(IPv6) Specification", STD 86, RFC 8200,
DOI 10.17487/RFC8200, July 2017,
<https://www.rfc-editor.org/info/rfc8200>.
[RFC8754] Filsfils, C., Ed., Dukes, D., Ed., Previdi, S., Leddy, J.,
Matsushima, S., and D. Voyer, "IPv6 Segment Routing Header
(SRH)", RFC 8754, DOI 10.17487/RFC8754, March 2020,
<https://www.rfc-editor.org/info/rfc8754>.
8.2. Informative References
[IANA-IPFIX]
IANA, "IP Flow Information Export (IPFIX) Entities",
<https://www.iana.org/assignments/ipfix>.
[OSPFV3-SRV6-EXT]
Li, Z., Hu, Z., Talaulikar, K., Ed., and P. Psenak,
"OSPFv3 Extensions for SRv6", Work in Progress, Internet-
Draft, draft-ietf-lsr-ospfv3-srv6-extensions-15, 21 June
2023, <https://datatracker.ietf.org/doc/html/draft-ietf-
lsr-ospfv3-srv6-extensions-15>.
[PCEP-SRV6-EXT]
Li, C., Kaladharan, P., Sivabalan, S., Koldychev, M., and
Y. Zhu, "Path Computation Element Communication Protocol
(PCEP) Extensions for Segment Routing leveraging the IPv6
dataplane", Work in Progress, Internet-Draft, draft-ietf-
pce-segment-routing-ipv6-20, 8 September 2023,
<https://datatracker.ietf.org/doc/html/draft-ietf-pce-
segment-routing-ipv6-20>.
[RFC7270] Yourtchenko, A., Aitken, P., and B. Claise, "Cisco-
Specific Information Elements Reused in IP Flow
Information Export (IPFIX)", RFC 7270,
DOI 10.17487/RFC7270, June 2014,
<https://www.rfc-editor.org/info/rfc7270>.
[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>.
[RFC8669] Previdi, S., Filsfils, C., Lindem, A., Ed., Sreekantiah,
A., and H. Gredler, "Segment Routing Prefix Segment
Identifier Extensions for BGP", RFC 8669,
DOI 10.17487/RFC8669, December 2019,
<https://www.rfc-editor.org/info/rfc8669>.
[RFC8986] Filsfils, C., Ed., Camarillo, P., Ed., Leddy, J., Voyer,
D., Matsushima, S., and Z. Li, "Segment Routing over IPv6
(SRv6) Network Programming", RFC 8986,
DOI 10.17487/RFC8986, February 2021,
<https://www.rfc-editor.org/info/rfc8986>.
[RFC9256] Filsfils, C., Talaulikar, K., Ed., Voyer, D., Bogdanov,
A., and P. Mattes, "Segment Routing Policy Architecture",
RFC 9256, DOI 10.17487/RFC9256, July 2022,
<https://www.rfc-editor.org/info/rfc9256>.
[RFC9352] Psenak, P., Ed., Filsfils, C., Bashandy, A., Decraene, B.,
and Z. Hu, "IS-IS Extensions to Support Segment Routing
over the IPv6 Data Plane", RFC 9352, DOI 10.17487/RFC9352,
February 2023, <https://www.rfc-editor.org/info/rfc9352>.
[SR-IPV6] Li, C., Negi, M., Sivabalan, S., Koldychev, M.,
Kaladharan, P., and Y. Zhu, "Path Computation Element
Communication Protocol (PCEP) Extensions for Segment
Routing leveraging the IPv6 dataplane", Work in Progress,
June 2023, <https://datatracker.ietf.org/doc/html/draft-
ietf-pce-segment-routing-ipv6-17>.
[SRV6-SRH-COM]
Cheng, W., Ed., Filsfils, C., Li, Z., Decraene, B., and F.
Clad, Ed., "Compressed SRv6 Segment List Encoding in SRH", Encoding", Work
in Progress, Internet-Draft, draft-ietf-spring-srv6-
srh-compression-06, 28 July draft-ietf-spring-srv6-srh-
compression-09, 23 October 2023,
<https://datatracker.ietf.org/doc/html/draft-ietf-spring-
srv6-srh-compression-06>.
srv6-srh-compression-09>.
Appendix A. IPFIX Encoding Examples
This appendix represents three different encodings for the newly
introduced IEs, for the example values in Table 3. The three
different encodings use the following IEs, respectively:
srhSegmentIPv6BasicList, srhSegmentIPv6ListSection, and
srhIPv6Section.
+========+=======+=====+==============+==========================+
| SRH Nr | SRH | SRH | Active | Segment List |
| | Flags | Tag | Segment Type | |
+========+=======+=====+==============+==========================+
| 1 | 0 | 123 | IS-IS [4] | 2001:db8::1, |
| | | | | 2001:db8::2, 2001:db8::3 |
+--------+-------+-----+--------------+--------------------------+
| 2 | 0 | 456 | IS-IS [4] | 2001:db8::4, 2001:db8::5 |
+--------+-------+-----+--------------+--------------------------+
| 3 | 0 | 789 | IS-IS [4] | 2001:db8::6 |
+--------+-------+-----+--------------+--------------------------+
Table 3: Three Observed SRH Headers and Their Associated
Routing Protocols
A.1. Three Observed SRH Headers and Their Routing Protocols
A.1.1. Template Record and Data Set with Segment Basic List
With encoding in Figure 1, the examples in Table 3 are represented
with the following IEs, where "=>" is used to indicate which IE is
mapped to given information:
* SR SRH Flags => srhFlagsIPv6 (492)
* SR SRH Tag => srhTagIPv6 (493)
* Active Segment Type => srhIPv6ActiveSegmentType (500)
* Segment List => srhSegmentIPv6BasicList (496)
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| SET ID = 2 | Length = 24 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Template ID = 256 | Field Count = 4 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|0| srhFlagsIPv6 = 492 | Field Length = 1 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|0| srhTagIPv6 = 493 | Field Length = 2 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|0|srhActiveSegmentIPv... = TBD9|
|0|srhIPv6ActiveSegmentType= 500| Field Length = 1 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|0|srhSegmentIPv6BasicList = 496| Field Length = 0xFFFF |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 1: Template Record with Basic List Encoding Format
In this example, the Template ID is 256, which will be used in the
Data Record. The field length for srhSegmentIPv6BasicList is 0xFFFF,
which means the length of this IE is variable, and the actual length
of this IE is indicated by the List Length field in the basicList
format as per [RFC6313].
The data set is represented as follows:
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| SET ID = 256 | Length = 136 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| srhFlagsIPv6 | srhTagIPv6 = 123 |srhActiveSegme| |srhIPv6Active | = 0
| |ntIPv... = 4 0 | |SegmentType= 4|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| 255 | List Length = 53 |semantic= |
| | |ordered |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| srhSegmentIPv6 = 494 | Field Length = 16 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Segment List[0] = 2001:db8::1 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ... |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ... |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ... |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Segment List[1] = 2001:db8::2 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ... |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ... |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ... |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Segment List[2] = 2001:db8::3 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ... |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ... |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ... |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| srhFlagsIPv6 | srhTagIPv6 = 456 | srhActiveSegme| srhIPv6Active |
| = 0 | | ntIPv... = 4 | SegmentType= 4|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| 255 | List Length = 37 |semantic= |
| | |ordered |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| srhSegmentIPv6 = 494 | Field Length = 16 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Segment List[0] = 2001:db8::4 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ... |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ... |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ... |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Segment List[1] = 2001:db8::5 (16 bytes) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ... |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ... |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ... |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| srhFlagsIPv6 | srhTagIPv6 = 789 | srhActiveSegme| srhIPv6Active |
| = 0 | | ntIPv... = 4 | SegmentType= 4|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| 255 | List Length = 21 |semantic= |
| | |ordered |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| srhSegmentIPv6 = 494 | Field Length = 16 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Segment List[0] = 2001:db8::6 ... |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ... |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ... |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ... |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 2: Data Set Encoding Format for Basic List
A.1.2. Template Record and Data Set with Segment List Section
With encoding in Figure 3, the examples in Table 3 are represented
with the following IEs, where "=>" is used to indicate which IE is
mapped to given information:
* SR SRH Flags => srhFlagsIPv6 (492)
* SR SRH Tag => srhTagIPv6 (493)
* Active Segment Type => srhIPv6ActiveSegmentType (500)
* Segment List => srhSegmentIPv6ListSection (497)
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| SET ID = 2 | Length = 24 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Template ID = 257 | Field Count = 4 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|0| srhFlagsIPv6 = 492 | Field Length = 1 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|0| srhTagIPv6 = 493 | Field Length = 2 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|0|srhActiveSegmentIPv... = TBD9|
|0|srhIPv6ActiveSegmentType= 500| Field Length = 1 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|0|srhSegmentIPv6ListSection=497| Field Length = 0xFFFF |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 3: Template Record with Segment List Section Encoding Format
In this example, the Template ID is 257, which will be used in the
Data Record. The field length for srhSegmentIPv6ListSection in the
Template Record is 0xFFFF, which means that the length of this IE is
variable: its actual length is encoded in the Data Set. Note that,
with an actual length inferior to 255 in the Data Record example, the
length field is encoded in 8 bits (Section 7 of [RFC7011]).
The data can be represented as follows:
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| SET ID = 257 | Length = 116 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| srhFlagsIPv6 | srhTagIPv6 = 123 | srhActiveSegme| srhIPv6Active |
| = 0 | | ntIPv... = 4 | SegmentType= 4|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Length = 48 | 2001:db8::1 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ... |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ... |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ... |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ... | 2001:db8::2 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ... |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ... |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ... |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ... | 2001:db8::3 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ... |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ... |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ... |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ... | srhFlagsIPv6 | srhTagIPv6 = 456 |
| | = 0 | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| srhActiveSegme| srhIPv6Active | Length = 32 | 2001:db8::4 |
| ntIPv... = 3 | SegmentType= 4| | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ... |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ... |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ... |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ... | 2001:db8::5 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ... |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ... |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ... |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ... |srhFlagsIPv6=0 | srhTagIPv6... srhTagIPv6 = |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| = 789 | srhActiveSegmentIPv6Type srhIPv6ActiveSegmentType = 4 | Length = 16 |
| | | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| 2001:db8::6 ... |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ... |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ... |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ... |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 4: Data Set Encoding Format for Segment List Section
A.1.3. Template Record and Data Set with SRH Section
With encoding in Figure 5, the examples in Table 3 are represented
with the following IEs, where "=>" is used to indicate which IE is
mapped to given information:
* SR SRH Flags + SR SRH Tag + Segment List => srhIPv6Section (499)
* Active Segment Type => srhIPv6ActiveSegmentType (500)
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| SET ID = 2 | Length = 16 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Template ID = 258 | Field Count = 2 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|0| srhActiveSegmentIP... = TBD9|
|0|srhIPv6ActiveSegmentType= 500| Field Length = 1 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|0| srhIPv6Section = 499 | Field Length = 0xFFFF |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 5: Template Record with SRH Section Encoding Format
In this example, the Template ID is 258, which will be used in the
Data Record. The field length for srhIPv6Section in the Template
Record is 0xFFFF, which means that the length of this IE is variable:
its actual length is encoded in the Data Set. Note that, with an
actual length inferior to 255 in the Data Record example, the length
field is encoded in 8 bits (Section 7 of [RFC7011]).
The data can be represented as follows:
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| SET ID = 258 | Length = (*) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| srhIPv6ActiveSegmentType = 4 | Length = (*) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Next Header | Hdr Ext Len | Routing Type | Segments Left |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Last Entry | Flags | Tag |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Segment List[0] 2001:db8::1 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ... |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ... |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ... |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Segment List[1] 2001:db8::2 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ... |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ... |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ... |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Segment List[2] 2001:db8::3 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ... |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ... |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ... |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
~ Optional Type Length Value objects (variable) ~
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| srhIPv6ActiveSegmentType = 4 | 0xFFFF |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Next Header | Hdr Ext Len | Routing Type | Segments Left |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Last Entry | Flags | Tag |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Segment List[0] 2001:db8::4 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ... |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ... |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ... |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Segment List[1] 2001:db8::5 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ... |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ... |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ... |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
~ Optional Type Length Value objects (variable) ~
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| srhIPv6ActiveSegmentType = 4 | 0xFFFF |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Next Header | Hdr Ext Len | Routing Type | Segments Left |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Last Entry | Flags | Tag |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Segment List[0] 2001:db8::6 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ... |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ... |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ... |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
~ Optional Type Length Value objects (variable) ~
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 6: Data Set Encoding Format for SRH Section
(*) The Length must be calculated to include the optional Type Length
Value objects.
A.2. Options Template Record and Data Set for SRv6 Segment Endpoint
Behavior and Locator Length
This appendix provides an SRv6 Endpoint Behavior Options Template
example, for the values presented in Table 4. In the Options
Template case, the srhActiveSegmentIPv6 IE is a Scope field.
+==========+===================+================+================+
| Entry Nr | SRH Endpoint IPv6 | SRH Endpoint | SRH Segment |
| | | Behavior | Locator Length |
+==========+===================+================+================+
| 1 | 2001:db8::1 | End [1] | 48 |
+----------+-------------------+----------------+----------------+
| 2 | 2001:db8::4 | End with NEXT- | 48 |
| | | CSID [43] | |
+----------+-------------------+----------------+----------------+
| 3 | 2001:db8::6 | End.DX6 [16] | 48 |
+----------+-------------------+----------------+----------------+
Table 4: Three Observed SRv6 Segment Endpoint Behaviors
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Set ID = 3 | Length = 24 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Template ID 259 | Field Count = 3 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Scope Field Count = 1 |0| srhActiveSegmentIPv6 = 495 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Scope 1 Field Length = 4 |0|srhSegmentEndpointBeh.. |0|srhSegmentIPv6End.Behav = 502|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Field Length = 1 |0|srhSegmentIPv6Lo.Length = 501|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Field Length = 4 | Padding |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 7: Segment Endpoint Behavior Options Template Record with SRH Section Encoding Format
In this example, the Template ID is 259, which will be used in the
Data Record.
The data set is represented as follows:
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| SET ID = 259 | Length = 28 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| srhActiveSegmentIPv6 = 2001:db8::1 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|
|srhSegmentIPv6EndpointBehavior |srhSegmentIPv6LocatorLength= 48|
|= End [1] | 48 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| srhActiveSegmentIPv6 = 2001:db8::4 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|
|srhSegmentIPv6EndpointBehavior |srhSegmentIPv6LocatorLength= 48|
|= End with NEXT-CSID [43] | 48 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| srhActiveSegmentIPv6 = 2001:db8::6 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|
|srhSegmentIPv6EndpointBehavior |srhSegmentIPv6LocatorLength= 48|
|= End.DX6 [16] | 48 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 8: Data Set Encoding Format for SRH Section Segment Endpoint Behaviors
(*) The Length must be calculated to include the optional Type Length
Value objects.
Acknowledgements
The authors would like to thank Yao Liu, Eduard Vasilenko, Bruno
Decraene, Mohamed Boucadair, Kamran Raza, Qin Wu, Jim Guichard, Tero
Kivinen, Paul Aitken, Roman Danyliw, John Scudder, Éric Vyncke, Erik
Kline, Lars Eggert, and Andrew Alston for their reviews and valuable
comments. And thank you to Paolo Lucente and Alex Huang Feng for the
implementation and validation.
Authors' Addresses
Thomas Graf
Swisscom
Binzring 17
CH-8045 Zurich
Switzerland
Email: thomas.graf@swisscom.com
Benoit Claise
Huawei
Email: benoit.claise@huawei.com
Pierre Francois
INSA-Lyon
Lyon
France
Email: pierre.francois@insa-lyon.fr