Export of IGP Flexible Algorithm Information in IPFIX
draft-liu-opsawg-ipfix-igp-algo-00
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| Document | Type | Active Internet-Draft (individual) | |
|---|---|---|---|
| Authors | Yao Liu , Liman Zhao | ||
| Last updated | 2025-11-28 | ||
| RFC stream | (None) | ||
| Intended RFC status | (None) | ||
| Formats | |||
| Stream | Stream state | (No stream defined) | |
| Consensus boilerplate | Unknown | ||
| RFC Editor Note | (None) | ||
| IESG | IESG state | I-D Exists | |
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| Send notices to | (None) |
draft-liu-opsawg-ipfix-igp-algo-00
OPSAWG Y. Liu
Internet-Draft L. Zhao
Intended status: Standards Track ZTE
Expires: 1 June 2026 28 November 2025
Export of IGP Flexible Algorithm Information in IPFIX
draft-liu-opsawg-ipfix-igp-algo-00
Abstract
This document introduces a new IPFIX information element (IE) to
identify the IGP flexible algorithm information related with the
Segment Identifier(SID) or the IPv4/IPv6 prefix.
Status of This Memo
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provisions of BCP 78 and BCP 79.
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This Internet-Draft will expire on 1 June 2026.
Copyright Notice
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document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal
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Please review these documents carefully, as they describe your rights
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3
3. IGP Flexible Algorithm Information in IPFIX . . . . . . . . . 3
4. Operational Considerations . . . . . . . . . . . . . . . . . 4
5. Security Considerations . . . . . . . . . . . . . . . . . . . 4
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 5
7. References . . . . . . . . . . . . . . . . . . . . . . . . . 5
7.1. Normative References . . . . . . . . . . . . . . . . . . 5
7.2. Informative References . . . . . . . . . . . . . . . . . 6
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 7
1. Introduction
[RFC9350] introduces the concept of Flexible Algorithm that allows
IGPs (ISIS, OSPFv2 and OSPFv3) to compute constraint-based path over
an SR-MPLS or an SRv6 network. In SR, the same prefix can be
associated with multiple algorithms.
[I-D.ietf-lsr-algorithm-related-adjacency-sid] comments that, besides
the SR-MPLS prefix SID, the algorithm can be also included as part of
an SR-MPLS Adjacency-SID advertisement in scenarios where multiple
algorithm share the same link resource.
[RFC9502] further extends IGP Flexible Algorithm so that it can be
used with regular IPv4 and IPv6 forwarding.
With IGP Flexible Algorithm, a physical network can be divided into
multiple logical planes. For each Flex-Algorithm, the path is
computed independently.
Below are the typical use cases when monitoring a traffic flow in a
network with IGP Flex-Algorithm enabled.
* Which Flex-Algorithm is the SR-MPLS SID or the SRv6 SID locator
belongs to ?
* Which Flex-Algorithm is the IPv4/IPv6 prefix related with ?
By only looking at the SR SID or the IP address itself, the above
questions could not be answered.
This document introduces a new IP Flow Information Export (IPFIX)
information element (IE) to identify the IGP Flexible algorithm
related with the SR segment identifier(SID) or the IPv4/IPv6 prefix.
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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 [RFC9350].
The following terms are used as defined in [RFC7011]:
* IPFIX
* IPFIX Information Elements
* Metering Process
* Template Record
* Data Record
* Collector
The following terms are used as defined in [RFC8402]:
* Segment Routing (SR)
* Segment List
* SRv6
* SR-MPLS
* Segment Identifier (SID)
The following terms are used as defined in [RFC9350]:
* Flexible Algorithm
3. IGP Flexible Algorithm Information in IPFIX
A new IE "flexAlgo" is defined in this document to identify the
Flexible Algorithm information related with an SR-MPLS SID, an SRv6
locator or an IPv4/IPv6 prefix, the IE carries the value of the IGP
Algorithm Types as in the IANA "IGP Algorithm Types" registry.
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Name: flexAlgo
ElementID: TBD1
Description: The 8-bit value that represents an IGP Flexible
Algorithm number related with an SR-MPLS SID, an SRv6 locator or
an IPv4/IPv6 prefix. The Flexible Algorithm number are specified
in the IANA "IGP Algorithm Types".
Abstract Data Type: unsigned8
Data Type Semantics: identifier
Additional Information: Specified in [RFC9350] and [RFC9502].
Reference: This document.
4. Operational Considerations
When used for monitoring SR-MPLS traffic flows, the IE "flexAlgo"
indicates the IGP flexible algorithm of the active SR-MPLS prefix/
adjacency SID or the IGP prefix related with the SR-MPLS SID, as in
[RFC8665], [RFC9350] and
[I-D.ietf-lsr-algorithm-related-adjacency-sid]. And the "flexAlgo"
is valid when the value of IE "IPFIX MPLS label type (Value
46)"[RFC9160] in the data record is 7 (OSPFv2 Segment Routing), 8
(OSPFv3 Segment Routing) or 9(IS-IS Segment Routing). In the absence
of the IE "IPFIX MPLS label type" in the IPFIX template record, how
to process the "flexAlgo" is implementation specific.
When used for monitoring SRv6 traffic flows, the IE "flexAlgo"
indicates the IGP algorithm related with the locator of the active
SRv6 SID as in [RFC9350], [RFC9352] and [RFC9513]. And the
"flexAlgo" is valid when the value of IE "IPFIX IPv6 SRH Segment Type
(Value 500)"[RFC9487] in the data record is 3 (OSPFv3 Segment
Routing) or 4 (IS-IS Segment Routing). In the absence of the "IPFIX
IPv6 SRH Segment Type", how to process the "flexAlgo" is
implementation specific.
When monitoring pure IPv4/IPv6 traffic flows, the IE "flexAlgo" can
be used to indicate the IGP algorithm related with the destination
IPv4/IPv6 address or the IPv4/IPv6 next hop address.
5. Security Considerations
There are no additional security considerations regarding allocation
of these new IPFIX IEs compared to [RFC7012].
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Other security considerations for IGP flexible algorithmin [RFC9350]
and [RFC9502] apply to this document.
6. IANA Considerations
This document requests IANA to create a new IE under the "IPFIX
Information Elements" registry [RFC7012] available at [IANA-IPFIX].
+-------+--------------------------------+
|Element| Name | Reference |
| ID | | |
+-------+-----------------+--------------+
| TBD1 | flexAlgo |This document |
+-------+-----------------+--------------+
7. References
7.1. Normative References
[IANA-IPFIX]
IANA, "IP Flow Information Export (IPFIX) Entities",
<https://www.iana.org/assignments/ipfix>.
[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>.
[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>.
[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>.
[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>.
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[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>.
[RFC9350] Psenak, P., Ed., Hegde, S., Filsfils, C., Talaulikar, K.,
and A. Gulko, "IGP Flexible Algorithm", RFC 9350,
DOI 10.17487/RFC9350, February 2023,
<https://www.rfc-editor.org/info/rfc9350>.
[RFC9502] Britto, W., Hegde, S., Kaneriya, P., Shetty, R., Bonica,
R., and P. Psenak, "IGP Flexible Algorithm in IP
Networks", RFC 9502, DOI 10.17487/RFC9502, November 2023,
<https://www.rfc-editor.org/info/rfc9502>.
7.2. Informative References
[I-D.ietf-lsr-algorithm-related-adjacency-sid]
Chen, R., Peng, S., Talaulikar, K., and P. Psenak,
"Algorithm Related IGP-Adjacency SID Advertisement", Work
in Progress, Internet-Draft, draft-ietf-lsr-algorithm-
related-adjacency-sid-08, 16 October 2025,
<https://datatracker.ietf.org/doc/html/draft-ietf-lsr-
algorithm-related-adjacency-sid-08>.
[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>.
[RFC9160] Graf, T., "Export of MPLS Segment Routing Label Type
Information in IP Flow Information Export (IPFIX)",
RFC 9160, DOI 10.17487/RFC9160, December 2021,
<https://www.rfc-editor.org/info/rfc9160>.
[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>.
[RFC9487] Graf, T., Claise, B., and P. Francois, "Export of Segment
Routing over IPv6 Information in IP Flow Information
Export (IPFIX)", RFC 9487, DOI 10.17487/RFC9487, November
2023, <https://www.rfc-editor.org/info/rfc9487>.
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[RFC9513] Li, Z., Hu, Z., Talaulikar, K., Ed., and P. Psenak,
"OSPFv3 Extensions for Segment Routing over IPv6 (SRv6)",
RFC 9513, DOI 10.17487/RFC9513, December 2023,
<https://www.rfc-editor.org/info/rfc9513>.
Authors' Addresses
Yao Liu
ZTE
Nanjing
China
Email: liu.yao71@zte.com.cn
Liman Zhao
ZTE
Email: zhao.liman@zte.com.cn
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