rfc9917.original   rfc9917.txt 
LSR Working Group P. Psenak Internet Engineering Task Force (IETF) P. Psenak
Internet-Draft J. Horn Request for Comments: 9917 J. Horn
Updates: 9350 (if approved) Cisco Systems Updates: 9350, 9843 Cisco Systems
Intended status: Standards Track A. Dhamija Category: Standards Track A. Dhamija
Expires: 6 February 2026 Arrcus ISSN: 2070-1721 Arrcus
5 August 2025 January 2026
IGP Flexible Algorithms Reverse Affinity Constraint IGP Flexible Algorithms Reverse Affinity Constraint
draft-ietf-lsr-igp-flex-algo-reverse-affinity-12
Abstract Abstract
An IGP Flexible Algorithm (Flex-Algorithm) enables the computation of An IGP Flexible Algorithm (Flex-Algorithm) enables the computation of
constraint-based paths within an IGP domain, allowing operators to constraint-based paths within an IGP domain, allowing operators to
influence path selection according to administrative policies. This influence path selection according to administrative policies. This
document defines an extension to Flex-Algorithm that allows the document defines an extension to Flex-Algorithm that allows the
inclusion or exclusion of links from path computation based on inclusion or exclusion of links from path computation based on
Administrative Groups (also known as link affinities) associated with Administrative Groups (also known as link affinities) associated with
the reverse direction of the path under computation. the reverse direction of the path under computation.
This extension enhances the path selection capabilities of Flex- This extension enhances the path selection capabilities of Flex-
Algorithm by enabling reverse-affinity-based constraints, which are Algorithm by enabling reverse-affinity-based constraints, which are
particularly useful for scenarios where path symmetry or directional particularly useful for scenarios where path symmetry or directional
link attributes are operationally significant. link attributes are operationally significant.
This document updates [RFC9350] and [I-D.ietf-lsr-flex-algo-bw-con] This document updates RFCs 9350 and 9843 by introducing the new IANA
by introducing the new IANA registry that specifies the ordered set registry that specifies the ordered set of rules that are used to
of rules that are used to prune links from the topology during the prune links from the topology during the Flex-Algorithm path
Flex-Algorithm path computation. computation.
Status of This Memo Status of This Memo
This Internet-Draft is submitted in full conformance with the This is an Internet Standards Track document.
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering
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working documents as Internet-Drafts. The list of current Internet-
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Internet-Drafts are draft documents valid for a maximum of six months This document is a product of the Internet Engineering Task Force
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time. It is inappropriate to use Internet-Drafts as reference received public review and has been approved for publication by the
material or to cite them other than as "work in progress." Internet Engineering Steering Group (IESG). Further information on
Internet Standards is available in Section 2 of RFC 7841.
This Internet-Draft will expire on 6 February 2026. 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/rfc9917.
Copyright Notice Copyright Notice
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Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3 1. Introduction
2. Requirements Language . . . . . . . . . . . . . . . . . . . . 3 2. Requirements Language
3. Use Case Example . . . . . . . . . . . . . . . . . . . . . . 4 3. Use Case Example
4. Deployment Consideration . . . . . . . . . . . . . . . . . . 4 4. Deployment Consideration
5. IS-IS Flexible Algorithm Exclude Reverse Admin Group 5. IS-IS Flexible Algorithm Exclude Reverse Admin Group Sub-TLV
Sub-TLV . . . . . . . . . . . . . . . . . . . . . . . . . 5
6. IS-IS Flexible Algorithm Include-Any Reverse Admin Group 6. IS-IS Flexible Algorithm Include-Any Reverse Admin Group
Sub-TLV . . . . . . . . . . . . . . . . . . . . . . . . . 6 Sub-TLV
7. IS-IS Flexible Algorithm Include-All Reverse Admin Group 7. IS-IS Flexible Algorithm Include-All Reverse Admin Group
Sub-TLV . . . . . . . . . . . . . . . . . . . . . . . . . 6 Sub-TLV
8. OSPF Flexible Algorithm Exclude Reverse Admin Group 8. OSPF Flexible Algorithm Exclude Reverse Admin Group Sub-TLV
Sub-TLV . . . . . . . . . . . . . . . . . . . . . . . . . 7 9. OSPF Flexible Algorithm Include-Any Reverse Admin Group Sub-TLV
9. OSPF Flexible Algorithm Include-Any Reverse Admin Group 10. OSPF Flexible Algorithm Include-All Reverse Admin Group Sub-TLV
Sub-TLV . . . . . . . . . . . . . . . . . . . . . . . . . 7 11. Calculation of Flexible Algorithm Paths
10. OSPF Flexible Algorithm Include-All Reverse Admin Group 12. IGP Flex-Algorithm Path Computation Rules Registry
Sub-TLV . . . . . . . . . . . . . . . . . . . . . . . . . 8 13. IANA Considerations
11. Calculation of Flexible Algorithm Paths . . . . . . . . . . . 8 13.1. Sub-Sub-TLVs for Flexible Algorithm Definition Sub-TLV
12. IGP Flex-Algorithm Path Computation Rules Registry . . . . . 9 13.2. OSPF Flexible Algorithm Definition TLV Sub-TLV Registry
13. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 9 13.3. IGP Flex-Algorithm Path Computation Rules Registry
13.1. Sub-Sub-TLVs for Flexible Algorithm Definition 14. Security Considerations
Sub-TLV . . . . . . . . . . . . . . . . . . . . . . . . 9 15. Normative References
13.2. OSPF Flexible Algorithm Definition TLV Sub-TLV 16. Informative References
Registry . . . . . . . . . . . . . . . . . . . . . . . . 10 Acknowledgments
13.3. IGP Flex-Algorithm Path Computation Rules Registry . . . 11 Authors' Addresses
14. Security Considerations . . . . . . . . . . . . . . . . . . . 15
15. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 15
16. Normative References . . . . . . . . . . . . . . . . . . . . 15
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 16
1. Introduction 1. Introduction
IGP protocols historically computed the best paths over the network IGP protocols historically computed the best paths over the network
solely based on the IGP metric assigned to the links. An IGP Flex- solely based on the IGP metric assigned to the links. An IGP Flex-
Algorithm as specified in [RFC9350] allows IGPs to compute Algorithm as specified in [RFC9350] allows IGPs to compute
constraint-based paths. Several mechanisms to include or exclude the constraint-based paths. Several mechanisms to include or exclude the
link during the Flex-Algorithm path calculation have been defined link during the Flex-Algorithm path calculation have been defined
already: already:
- link inclusion or exclusion based on the presence of a specific * link inclusion or exclusion based on the presence of a specific
Admin Group(s) - [RFC9350] Admin Group(s) [RFC9350]
- link exclusion based on the presence of a specific Shared Risk * link exclusion based on the presence of a specific Shared Risk
Link Group (SRLG) - [RFC9350] Link Group (SRLG) [RFC9350]
- link exclusion based on minimum bandwidth - * link exclusion based on minimum bandwidth [RFC9843]
[I-D.ietf-lsr-flex-algo-bw-con]
- link exclusion based on maximum delay - * link exclusion based on maximum delay [RFC9843]
[I-D.ietf-lsr-flex-algo-bw-con]
This document extends IGP Flex-Algorithm with additional constraints This document extends IGP Flex-Algorithm with additional constraints
for inclusion or exclusion of links in the path based on Admin Groups for inclusion or exclusion of links in the path based on Admin Groups
associated with the reverse direction of the SPF path computation. associated with the reverse direction of the Shortest Path First
(SPF) computation.
This document updates [RFC9350] and [I-D.ietf-lsr-flex-algo-bw-con] This document updates [RFC9350] and [RFC9843] by creating the new
by creating the new IANA registry that specifies the ordered set of IANA registry that specifies the ordered set of rules that are used
rules that are used to prune links from the topology during the Flex- to prune links from the topology during the Flex-Algorithm path
Algorithm path computation (refer to Section 12). computation (refer to Section 12).
The term OSPF in this document is used to cover both OSPFv2 and The term OSPF in this document is used to cover both OSPFv2 and
OSPFv3 protocols. OSPFv3 protocols.
2. Requirements Language 2. Requirements Language
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in BCP "OPTIONAL" in this document are to be interpreted as described in
14 [RFC2119] [RFC8174] when, and only when, they appear in all BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all
capitals, as shown here. capitals, as shown here.
3. Use Case Example 3. Use Case Example
The Flexible Algorithm definition (FAD) can specify Extended The Flexible Algorithm Definition (FAD) can specify Extended
Administrative Groups that are used by the operator to include or Administrative Groups that are used by the operator to include or
exclude links during the Flex-Algorithm path computation [RFC9350]. exclude links during the Flex-Algorithm path computation [RFC9350].
These link Extended Administrative Groups are checked in the path These link Extended Administrative Groups are checked in the path
direction of the SPF computation, e.g., in the direction from the direction of the SPF computation, e.g., in the direction from the
root vertex toward verticies of increasing distance. root vertex toward vertices of increasing distance.
In certain scenarios, it is beneficial to evaluate the Extended In certain scenarios, it is beneficial to evaluate the Extended
Administrative Groups associated with the reverse direction of a Administrative Groups associated with the reverse direction of a
link, rather than solely those in the direction of path computation. link, rather than solely those in the direction of path computation.
Consider a point-to-point link represented as a pair of directed Consider a point-to-point link represented as a pair of directed
edges between two nodes, A and B. When computing a path from A to B, edges between two nodes, A and B. When computing a path from A to B,
issues such as input errors on the link, detectable only at the issues such as input errors on the link, detectable only at the
receiving node B, may be operationally significant. An operator receiving node B, may be operationally significant. An operator
might monitor metrics like CRC errors or other input-related faults might monitor metrics like Cyclic Redundancy Check (CRC) errors or
at node B and apply thresholds over a defined observation period. If other input-related faults at node B and apply thresholds over a
such a threshold is exceeded, node B may locally assign specific defined observation period. If such a threshold is exceeded, node B
Extended Administrative Groups to the link in the direction from B to may locally assign specific Extended Administrative Groups to the
A. link in the direction from B to A.
To accommodate this operational intent, the Flex-Algorithm can be To accommodate this operational intent, the Flex-Algorithm can be
extended to inspect the Extended Administrative Groups of the extended to inspect the Extended Administrative Groups of the
reverse-direction edge (from B to A) when evaluating the forward- reverse-direction edge (from B to A) when evaluating the forward-
direction edge (from A to B) during path computation. This enables direction edge (from A to B) during path computation. This enables
the exclusion of links from the computed topology based on conditions the exclusion of links from the computed topology based on conditions
detected at the far end of the link, improving network reliability detected at the far end of the link, improving network reliability
and policy control. and policy control.
4. Deployment Consideration 4. Deployment Consideration
Threshold based setting of the link Extended Administrative Groups Threshold-based setting of the link Extended Administrative Groups
must be done with care to avoid excessive flooding and constant Flex- must be done with care to avoid excessive flooding and constant Flex-
Algorithm path re-calculation. Algorithm path recalculation.
One possible approach is to use two different thresholds when setting One possible approach is to use two different thresholds when setting
and un-setting the Extended Administrative Group on the link. For and unsetting the Extended Administrative Group on the link. For
example, when setting the Extended Administrative Group on the link example, when setting the Extended Administrative Group on the link
based on the percentage of certain incoming errors, higher threshold based on the percentage of certain incoming errors, higher threshold
is used for setting and lower threshold is used for un-setting the is used for setting and lower threshold is used for unsetting the
Extended Administrative Group on the link. Extended Administrative Group on the link.
Many implementations provide a throttling mechanism that limits the Many implementations provide a throttling mechanism that limits the
rate at which the LSP in case of ISIS, or LSA in case of OSPFv2 and rate at which the Label Switched Path (LSP) in case of IS-IS, or Link
OSPFv3, is updated at the originator. Such mechanism is typically State Advertisement (LSA) in case of OSPFv2 and OSPFv3, is updated at
not specific to any particular link attribute, but rather considers the originator. Such mechanism is typically not specific to any
any change in the LSP or LSA. Usage of such throttling mechanism can particular link attribute, but rather considers any change in the LSP
also be used to avoid frequent changes in the setting of the Extended or LSA. Usage of such throttling mechanism can also be used to avoid
Administrative Group on a link to affect the stability of the frequent changes in the setting of the Extended Administrative Group
receivers. on a link to affect the stability of the receivers.
5. IS-IS Flexible Algorithm Exclude Reverse Admin Group Sub-TLV 5. IS-IS Flexible Algorithm Exclude Reverse Admin Group Sub-TLV
The IS-IS Flexible Algorithm Exclude Reverse Admin Group (FAERAG) The IS-IS Flexible Algorithm Exclude Reverse Admin Group (FAERAG)
Sub-TLV is used to advertise the exclude rule that is used during the Sub-TLV is used to advertise the exclude rule that is used during the
Flex-Algorithm path calculation as specified in Section 11. Flex-Algorithm path calculation as specified in Section 11.
The IS-IS FAERAG Sub-TLV is a Sub-TLV of the IS-IS FAD Sub-TLV. It The IS-IS FAERAG Sub-TLV is a sub-TLV of the IS-IS FAD Sub-TLV. It
has the following format: has the following format:
0 1 2 3 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 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 | | Type | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Extended Admin Group | | Extended Admin Group |
+- -+ +- -+
| ... | | ... |
skipping to change at page 5, line 26 skipping to change at line 196
0 1 2 3 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 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 | | Type | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Extended Admin Group | | Extended Admin Group |
+- -+ +- -+
| ... | | ... |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
where: where:
Type (1 octet): 10 Type (1 octet): 10
Length (1 octet): Variable, dependent on the size of the Extended Length (1 octet): Variable, dependent on the size of the Extended
Admin Group. The length MUST be a multiple of 4 octets. If the Admin Group. The length MUST be a multiple of 4 octets. If the
length is not a multiple of 4 octets, the entire Sub-TLV MUST be length is not a multiple of 4 octets, the entire sub-TLV MUST be
ignored by the receiver. ignored by the receiver.
Extended Administrative Group: Extended Administrative Group as Extended Administrative Group: Extended Administrative Group as
defined in [RFC7308]. defined in [RFC7308].
The IS-IS FAERAG Sub-TLV MUST NOT appear more than once in a single The IS-IS FAERAG Sub-TLV MUST NOT appear more than once in a single
IS-IS FAD Sub-TLV. If it appears more than once, the IS-IS FAD Sub- IS-IS FAD Sub-TLV. If it appears more than once, the IS-IS FAD Sub-
TLV MUST be ignored by the receiver. TLV MUST be ignored by the receiver.
The IS-IS FAERAG Sub-TLV MUST NOT appear more than once in the set of The IS-IS FAERAG Sub-TLV MUST NOT appear more than once in the set of
FAD sub-TLVs for a given Flex-Algorithm from a given IS. If it FAD Sub-TLVs for a given Flex-Algorithm from a given IS. If it
appears more than once in such set, the IS-IS FAERAG Sub-TLV in the appears more than once in such set, the IS-IS FAERAG Sub-TLV in the
first occurrence in the lowest numbered LSP from a given IS MUST be first occurrence in the lowest-numbered LSP from a given IS MUST be
used and any other occurrences MUST be ignored by the receiver. used and any other occurrences MUST be ignored by the receiver.
6. IS-IS Flexible Algorithm Include-Any Reverse Admin Group Sub-TLV 6. IS-IS Flexible Algorithm Include-Any Reverse Admin Group Sub-TLV
The IS-IS Flexible Algorithm Include-Any Reverse Admin Group Sub-TLV The IS-IS Flexible Algorithm Include-Any Reverse Admin Group Sub-TLV
is used to advertise the include-any rule that is used during the is used to advertise the include-any rule that is used during the
Flex-Algorithm path calculation as specified in Section 11. Flex-Algorithm path calculation as specified in Section 11.
The format of the IS-IS Flexible Algorithm Include-Any Reverse Admin The format of the IS-IS Flexible Algorithm Include-Any Reverse Admin
Group Sub-TLV is identical to the format of the FAERAG Sub-TLV in Group Sub-TLV is identical to the format of the FAERAG Sub-TLV in
skipping to change at page 6, line 24 skipping to change at line 238
IANA has assigned Type value of 11 for the IS-IS Flexible Algorithm IANA has assigned Type value of 11 for the IS-IS Flexible Algorithm
Include-Any Reverse Admin Group Sub-TLV. Include-Any Reverse Admin Group Sub-TLV.
The IS-IS Flexible Algorithm Include-Any Reverse Admin Group Sub-TLV The IS-IS Flexible Algorithm Include-Any Reverse Admin Group Sub-TLV
MUST NOT appear more than once in a single IS-IS FAD Sub-TLV. If it MUST NOT appear more than once in a single IS-IS FAD Sub-TLV. If it
appears more than once, the IS-IS FAD Sub-TLV MUST be ignored by the appears more than once, the IS-IS FAD Sub-TLV MUST be ignored by the
receiver. receiver.
The IS-IS Flexible Algorithm Include-Any Reverse Admin Group Sub-TLV The IS-IS Flexible Algorithm Include-Any Reverse Admin Group Sub-TLV
MUST NOT appear more than once in the set of FAD sub-TLVs for a given MUST NOT appear more than once in the set of FAD Sub-TLVs for a given
Flex-Algorithm from a given IS. If it appears more than once in such Flex-Algorithm from a given IS. If it appears more than once in such
set, the IS-IS Flexible Algorithm Include-Any Reverse Admin Group set, the IS-IS Flexible Algorithm Include-Any Reverse Admin Group
Sub-TLV in the first occurrence in the lowest numbered LSP from a Sub-TLV in the first occurrence in the lowest-numbered LSP from a
given IS MUST be used and any other occurrences MUST be ignored by given IS MUST be used and any other occurrences MUST be ignored by
the receiver. the receiver.
7. IS-IS Flexible Algorithm Include-All Reverse Admin Group Sub-TLV 7. IS-IS Flexible Algorithm Include-All Reverse Admin Group Sub-TLV
The IS-IS Flexible Algorithm Include-All Reverse Admin Group Sub-TLV The IS-IS Flexible Algorithm Include-All Reverse Admin Group Sub-TLV
is used to advertise the include-all rule that is used during the is used to advertise the include-all rule that is used during the
Flex-Algorithm path calculation as specified in Section 11. Flex-Algorithm path calculation as specified in Section 11.
The format of the IS-IS Flexible Algorithm Include-All Reverse Admin The format of the IS-IS Flexible Algorithm Include-All Reverse Admin
skipping to change at page 6, line 50 skipping to change at line 264
IANA has assigned Type value of 12 for the IS-IS Flexible Algorithm IANA has assigned Type value of 12 for the IS-IS Flexible Algorithm
Include-All Reverse Admin Group Sub-TLV. Include-All Reverse Admin Group Sub-TLV.
The IS-IS Flexible Algorithm Include-All Reverse Admin Group Sub-TLV The IS-IS Flexible Algorithm Include-All Reverse Admin Group Sub-TLV
MUST NOT appear more than once in a single IS-IS FAD Sub-TLV. If it MUST NOT appear more than once in a single IS-IS FAD Sub-TLV. If it
appears more than once, the IS-IS FAD Sub-TLV MUST be ignored by the appears more than once, the IS-IS FAD Sub-TLV MUST be ignored by the
receiver. receiver.
The IS-IS Flexible Algorithm Include-All Reverse Admin Group Sub-TLV The IS-IS Flexible Algorithm Include-All Reverse Admin Group Sub-TLV
MUST NOT appear more than once in the set of FAD sub-TLVs for a given MUST NOT appear more than once in the set of FAD Sub-TLVs for a given
Flex-Algorithm from a given IS. If it appears more than once in such Flex-Algorithm from a given IS. If it appears more than once in such
set, the IS-IS Flexible Algorithm Include-All Reverse Admin Group set, the IS-IS Flexible Algorithm Include-All Reverse Admin Group
Sub-TLV in the first occurrence in the lowest numbered LSP from a Sub-TLV in the first occurrence in the lowest-numbered LSP from a
given IS MUST be used and any other occurrences MUST be ignored by given IS MUST be used and any other occurrences MUST be ignored by
the receiver. the receiver.
8. OSPF Flexible Algorithm Exclude Reverse Admin Group Sub-TLV 8. OSPF Flexible Algorithm Exclude Reverse Admin Group Sub-TLV
The OSPF Flexible Algorithm Exclude Reverse Admin Group (FAERAG) Sub- The OSPF Flexible Algorithm Exclude Reverse Admin Group (FAERAG) Sub-
TLV is used to advertise the exclude rule that is used during the TLV is used to advertise the exclude rule that is used during the
Flex-Algorithm path calculation as specified in Section 11. Flex-Algorithm path calculation as specified in Section 11.
The OSPF FAERAG Sub-TLV is a Sub-TLV of the OSPF FAD TLV. It has the The OSPF FAERAG Sub-TLV is a sub-TLV of the OSPF FAD TLV. It has the
following format: following format:
0 1 2 3 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 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 | | Type | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Extended Admin Group | | Extended Admin Group |
+- -+ +- -+
| ... | | ... |
skipping to change at page 7, line 26 skipping to change at line 289
0 1 2 3 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 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 | | Type | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Extended Admin Group | | Extended Admin Group |
+- -+ +- -+
| ... | | ... |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
where: where:
Type (2 octets): 10 Type (2 octets): 10
Length (2 octets): Variable, dependent on the size of the Extended Length (2 octets): Variable, dependent on the size of the Extended
Admin Group. The length MUST be a multiple of 4 octets. If the Admin Group. The length MUST be a multiple of 4 octets. If the
length is not a multiple of 4 octets, the entire Sub-TLV MUST be length is not a multiple of 4 octets, the entire sub-TLV MUST be
ignored by the receiver. ignored by the receiver.
Extended Administrative Group: Extended Administrative Group as Extended Administrative Group: Extended Administrative Group as
defined in [RFC7308]. defined in [RFC7308].
The OSPF FAERAG Sub-TLV MUST NOT appear more than once in an OSPF FAD The OSPF FAERAG Sub-TLV MUST NOT appear more than once in an OSPF FAD
TLV. If it appears more than once, the OSPF FAD TLV MUST be ignored TLV. If it appears more than once, the OSPF FAD TLV MUST be ignored
by the receiver. by the receiver.
9. OSPF Flexible Algorithm Include-Any Reverse Admin Group Sub-TLV 9. OSPF Flexible Algorithm Include-Any Reverse Admin Group Sub-TLV
The OSPF Flexible Algorithm Include-Any Reverse Admin Group Sub-TLV The OSPF Flexible Algorithm Include-Any Reverse Admin Group Sub-TLV
is used to advertise the include-any rule that is used during the is used to advertise the include-any rule that is used during the
skipping to change at page 8, line 22 skipping to change at line 333
10. OSPF Flexible Algorithm Include-All Reverse Admin Group Sub-TLV 10. OSPF Flexible Algorithm Include-All Reverse Admin Group Sub-TLV
The OSPF Flexible Algorithm Include-All Reverse Admin Group Sub-TLV The OSPF Flexible Algorithm Include-All Reverse Admin Group Sub-TLV
is used to advertise the include-all rule that is used during the is used to advertise the include-all rule that is used during the
Flex-Algorithm path calculation as specified in Section 11. Flex-Algorithm path calculation as specified in Section 11.
The format of the OSPF Flexible Algorithm Include-All Reverse Admin The format of the OSPF Flexible Algorithm Include-All Reverse Admin
Group Sub-TLV is identical to the format of the OSPF FAERAG Sub-TLV Group Sub-TLV is identical to the format of the OSPF FAERAG Sub-TLV
in Section 8. in Section 8.
IANA has assigned Type value of 12 for OSPF Flexible Algorithm IANA has assigned Type value of 12 for the OSPF Flexible Algorithm
Include-All Reverse Admin Group Sub-TLV. Include-All Reverse Admin Group Sub-TLV.
The OSPF Flexible Algorithm Include-All Reverse Admin Group Sub-TLV The OSPF Flexible Algorithm Include-All Reverse Admin Group Sub-TLV
MUST NOT appear more than once in an OSPF FAD TLV. If it appears MUST NOT appear more than once in an OSPF FAD TLV. If it appears
more than once, the OSPF FAD TLV MUST be ignored by the receiver. more than once, the OSPF FAD TLV MUST be ignored by the receiver.
11. Calculation of Flexible Algorithm Paths 11. Calculation of Flexible Algorithm Paths
The following procedures augment the rules defined in Section 13 of The following procedures augment the rules defined in Section 13 of
[RFC9350] by introducing additional constraints based on [RFC9350] by introducing additional constraints based on
Administrative Groups (AGs) associated with the reverse direction of Administrative Groups (AGs) associated with the reverse direction of
a link. a link.
Check if any exclude reverse Admin Group rule is part of the Flex- * Check if any exclude reverse Admin Group rule is part of the Flex-
Algorithm definition. If such exclude rule exists, check if any Algorithm definition. If such exclude rule exists, check if any
Admin Group that is part of the exclude rule is also set on the Admin Group that is part of the exclude rule is also set on the
link in the reverse direction. If such Admin Group is set on the link in the reverse direction. If such Admin Group is set on the
link in the reverse direction, the link MUST be pruned from the link in the reverse direction, the link MUST be pruned from the
computation. computation.
Check if any include-any reverse Admin Group rule is part of the * Check if any include-any reverse Admin Group rule is part of the
Flex-Algorithm definition. If such include-any rule exists, check Flex-Algorithm definition. If such include-any rule exists, check
if any Admin Group that is part of the include-any rule is also if any Admin Group that is part of the include-any rule is also
set on the link in the reverse direction. If no such Admin Group set on the link in the reverse direction. If no such Admin Group
is set on the link in the reverse direction, the link MUST be is set on the link in the reverse direction, the link MUST be
pruned from the computation. pruned from the computation.
Check if any include-all reverse Admin Group rule is part of the * Check if any include-all reverse Admin Group rule is part of the
Flex-Algorithm definition. If such include-all rule exists, check Flex-Algorithm definition. If such include-all rule exists, check
if all Admin Groups that are part of the include-all rule are also if all Admin Groups that are part of the include-all rule are also
set on the link in the reverse direction. If all such Admin set on the link in the reverse direction. If all such Admin
Groups are not set on the link in the reverse direction, the link Groups are not set on the link in the reverse direction, the link
MUST be pruned from the computation. MUST be pruned from the computation.
Please see rules 8, 9, and 10 in Section 13.3 for these added rules. Please see rules 8, 9, and 10 in Section 13.3 for these added rules.
12. IGP Flex-Algorithm Path Computation Rules Registry 12. IGP Flex-Algorithm Path Computation Rules Registry
skipping to change at page 9, line 28 skipping to change at line 386
across multiple documents progressing independently. The new "IGP across multiple documents progressing independently. The new "IGP
Flex-Algorithm Path Computation Rules" registry has been created and Flex-Algorithm Path Computation Rules" registry has been created and
is specified in Section 13.3. is specified in Section 13.3.
This section provides the guidance for designated experts on This section provides the guidance for designated experts on
evaluating new registrations in the "IGP Flex-Algorithm Path evaluating new registrations in the "IGP Flex-Algorithm Path
Computation Rules" registry: Computation Rules" registry:
1. When a new constraint is defined, the rule associated with that 1. When a new constraint is defined, the rule associated with that
constraint MAY be inserted at any position. Backwards constraint MAY be inserted at any position. Backwards
compatibility is guaranteed because nodes which don't support the compatibility is guaranteed because nodes that don't support the
new constraint will not participate in an algorithm where the FAD new constraint will not participate in an algorithm where the FAD
specifies a constraint they don't support. specifies a constraint they don't support.
2. The relative ordering of existing rules MUST NOT be altered. 2. The relative ordering of existing rules MUST NOT be altered.
Doing so has the potential to create backwards compatibility Doing so has the potential to create backwards compatibility
issues. issues.
3. Deletion of the rules MUST NOT be done. Given that the rules are 3. Deletion of the rules MUST NOT be done. Given that the rules are
only used conditionally based on the information carried in the only used conditionally based on the information carried in the
winning FAD, deletion of the rule is not necessary. winning FAD, deletion of the rule is not necessary.
4. Merging or repeating of the rules MUST NOT be done. 4. Merging or repeating of the rules MUST NOT be done.
13. IANA Considerations 13. IANA Considerations
13.1. Sub-Sub-TLVs for Flexible Algorithm Definition Sub-TLV 13.1. Sub-Sub-TLVs for Flexible Algorithm Definition Sub-TLV
This document makes the following registration in the "IS-IS Sub-Sub- IANA has registered the following in the "IS-IS Sub-Sub-TLVs for
TLVs for Flexible Algorithm Definition Sub-TLV" registry under "IS-IS Flexible Algorithm Definition Sub-TLV" registry under the "IS-IS TLV
TLV Codepoints" registry group: Codepoints" registry group:
Type: 10
Description: Flexible Algorithm Exclude Reverse Admin Group
MP-TLV Applicability: N
Reference: This document (Section 5).
Type: 11
Description: Flexible Algorithm Include-Any Reverse Admin Group
MP-TLV Applicability: N
Reference: This document (Section 6).
Type: 12
Description: Flexible Algorithm Include-All Reverse Admin Group Type: 10
Description: Flexible Algorithm Exclude Reverse Admin Group
MP: n
Reference: RFC 9917, Section 5
MP-TLV Applicability: N Type: 11
Description: Flexible Algorithm Include-Any Reverse Admin Group
MP: n
Reference: RFC 9917, Section 6
Reference: This document (Section 7). Type: 12
Description: Flexible Algorithm Include-All Reverse Admin Group
MP: n
Reference: RFC 9917, Section 7
13.2. OSPF Flexible Algorithm Definition TLV Sub-TLV Registry 13.2. OSPF Flexible Algorithm Definition TLV Sub-TLV Registry
This document makes the following registration in the "OSPF Flexible This document makes the following registration in the "OSPF Flexible
Algorithm Definition TLV Sub-TLVs" registry under "Open Shortest Path Algorithm Definition TLV Sub-TLVs" registry under the "Open Shortest
First (OSPF) Parameters" registry group: Path First (OSPF) Parameters" registry group:
Type: 10
Description: Flexible Algorithm Exclude Reverse Admin Group
Reference: This document (Section 8).
Type: 11
Description: Flexible Algorithm Include-Any Reverse Admin Group
Reference: This document (Section 9).
Type: 12 Type: 10
Description: Flexible Algorithm Exclude Reverse Admin Group
Reference: RFC 9917, Section 8
Description: Flexible Algorithm Include-All Reverse Admin Group Type: 11
Description: Flexible Algorithm Include-Any Reverse Admin Group
Reference: RFC 9917, Section 9
Reference: This document (Section 10). Type: 12
Description: Flexible Algorithm Include-All Reverse Admin Group
Reference: RFC 9917, Section 10
13.3. IGP Flex-Algorithm Path Computation Rules Registry 13.3. IGP Flex-Algorithm Path Computation Rules Registry
This document creates a new registry called "IGP Flex-Algorithm Path IANA has created a new registry called "IGP Flex-Algorithm Path
Computation Rules Registry" within the "Interior Gateway Protocol Computation Rules" within the "Interior Gateway Protocol (IGP)
(IGP) Parameters" registry group. The registration procedure for the Parameters" registry group. The registration procedure for the new
new registry is "Expert Review". Section 12 provides guidance for registry is Expert Review [RFC8126]. Section 12 provides guidance
Designated Experts. for designated experts.
The "IGP Flex-Algo Path Computation Rules" specifies the ordered set The "IGP Flex-Algorithm Path Computation Rules" registry specifies
of rules that are used to prune links from the topology during the the ordered set of rules that are used to prune links from the
Flex-Algorithm path computation. topology during the Flex-Algorithm path computation.
There is no upper bound on the number of rules that the registry There is no upper bound on the number of rules that the registry
supports. supports.
+==========+======================+=================================+ +==========+===========================================+===========+
| Sequence | Description | Reference | | Sequence | Description | Reference |
| Number | | | | Number | | |
+==========+======================+=================================+ +==========+===========================================+===========+
| 1 | Check if any | Section 13 of [RFC9350] | | 1 | Check if any exclude Administrative Group | Section |
| | exclude | | | | rule is part of the Flex-Algorithm | 13 of |
| | Administrative | | | | Definition. If such exclude rule exists, | [RFC9350] |
| | Group rule is part | | | | check if any color that is part of the | |
| | of the Flex- | | | | exclude rule is also set on the link. If | |
| | Algorithm | | | | such a color is set, the link MUST be | |
| | Definition. If | | | | pruned from the computation | |
| | such exclude rule | | +----------+-------------------------------------------+-----------+
| | exists, check if | | | 2 | Check if any exclude SRLG rule is part of | Section |
| | any color that is | | | | the Flex-Algorithm Definition. If such | 13 of |
| | part of the exclude | | | | exclude rule exists, check if the link is | [RFC9350] |
| | rule is also set on | | | | part of any SRLG that is also part of the | |
| | the link. If such | | | | SRLG exclude rule. If the link is part | |
| | a color is set, the | | | | of such SRLG, the link MUST be pruned | |
| | link MUST be pruned | | | | from the computation. | |
| | from the | | +----------+-------------------------------------------+-----------+
| | computation | | | 3 | Check if any include-any Administrative | Section |
+----------+----------------------+---------------------------------+ | | Group rule is part of the Flex-Algorithm | 13 of |
| 2 | Check if any | Section 13 of [RFC9350] | | | Definition. If such include-any rule | [RFC9350] |
| | exclude SRLG rule | | | | exists, check if any color that is part | |
| | is part of the | | | | of the include-any rule is also set on | |
| | Flex-Algorithm | | | | the link. If no such color is set, the | |
| | Definition. If | | | | link MUST be pruned from the computation. | |
| | such exclude rule | | +----------+-------------------------------------------+-----------+
| | exists, check if | | | 4 | Check if any include-all Administrative | Section |
| | the link is part of | | | | Group rule is part of the Flex-Algorithm | 13 of |
| | any SRLG that is | | | | Definition. If such include-all rule | [RFC9350] |
| | also part of the | | | | exists, check if all colors that are part | |
| | SRLG exclude rule. | | | | of the include-all rule are also set on | |
| | If the link is part | | | | the link. If all such colors are not set | |
| | of such SRLG, the | | | | on the link, the link MUST be pruned from | |
| | link MUST be pruned | | | | the computation. | |
| | from the | | +----------+-------------------------------------------+-----------+
| | computation. | | | 5 | If the Flex-Algorithm Definition uses | Section |
+----------+----------------------+---------------------------------+ | | something other than the IGP metric | 13 of |
| 3 | Check if any | Section 13 of [RFC9350] | | | (Section 5 of [RFC9350]), and such metric | [RFC9350] |
| | include-any | | | | is not advertised for the particular link | |
| | Administrative | | | | in a topology for which the computation | |
| | Group rule is part | | | | is done, such link MUST be pruned from | |
| | of the Flex- | | | | the computation. A metric of value 0 | |
| | Algorithm | | | | MUST NOT be assumed in such a case. | |
| | Definition. If | | +----------+-------------------------------------------+-----------+
| | such include-any | | | 6 | Check if any exclude FAEMB rule is part | Section 6 |
| | rule exists, check | | | | of the Flex-Algorithm definition. If | of |
| | if any color that | | | | such exclude rule exists and the link has | [RFC9843] |
| | is part of the | | | | Maximum Link Bandwidth advertised, check | |
| | include-any rule is | | | | if the link bandwidth satisfies the FAEMB | |
| | also set on the | | | | rule. If the link does not satisfy the | |
| | link. If no such | | | | FAEMB rule, the link MUST be pruned from | |
| | color is set, the | | | | the Flex-Algorithm computation | |
| | link MUST be pruned | | +----------+-------------------------------------------+-----------+
| | from the | | | 7 | Check if any exclude FAEMD rule is part | Section 6 |
| | computation | | | | of the Flex-Algorithm definition. If | of |
+----------+----------------------+---------------------------------+ | | such exclude rule exists and the link has | [RFC9843] |
| 4 | Check if any | Section 13 of [RFC9350] | | | Min Unidirectional link delay advertised, | |
| | include-all | | | | check if the link delay satisfies the | |
| | Administrative | | | | FAEMD rule. If the link does not satisfy | |
| | Group rule is part | | | | the FAEMD rule, the link MUST be pruned | |
| | of the Flex- | | | | from the Flex-Algorithm computation. | |
| | Algorithm | | +----------+-------------------------------------------+-----------+
| | Definition. If | | | 8 | Check if any exclude reverse Admin Group | Section |
| | such include-all | | | | rule is part of the Flex-Algorithm | 11 of RFC |
| | rule exists, check | | | | definition. If such exclude rule exists, | 9917 |
| | if all colors that | | | | check if any Admin Group that is part of | |
| | are part of the | | | | the exclude rule is also set on the link | |
| | include-all rule | | | | in the reverse direction. If such Admin | |
| | are also set on the | | | | Group is set on the link in the reverse | |
| | link. If all such | | | | direction, the link MUST be pruned from | |
| | colors are not set | | | | the computation. | |
| | on the link, the | | +----------+-------------------------------------------+-----------+
| | link MUST be pruned | | | 9 | Check if any include-any reverse Admin | Section |
| | from the | | | | Group rule is part of the Flex-Algorithm | 11 of RFC |
| | computation. | | | | definition. If such include-any rule | 9917 |
+----------+----------------------+---------------------------------+ | | exists, check if any Admin Group that is | |
| 5 | If the Flex- | Section 13 of [RFC9350] | | | part of the include-any rule is also set | |
| | Algorithm | | | | on the link in the reverse direction. If | |
| | Definition uses | | | | no such Admin Group is set on the link in | |
| | something other | | | | the reverse direction, the link MUST be | |
| | than the IGP metric | | | | pruned from the computation | |
| | (Section 5 of | | +----------+-------------------------------------------+-----------+
| | [RFC9350]), and | | | 10 | Check if any include-all reverse Admin | Section |
| | such metric is not | | | | Group rule is part of the Flex-Algorithm | 11 of RFC |
| | advertised for the | | | | definition. If such include-all rule | 9917 |
| | particular link in | | | | exists, check if all Admin Groups that | |
| | a topology for | | | | are part of the include-all rule are also | |
| | which the | | | | set on the link in the reverse direction. | |
| | computation is | | | | If all such Admin Groups are not set on | |
| | done, such link | | | | the link in the reverse direction, the | |
| | MUST be pruned from | | | | link MUST be pruned from the computation. | |
| | the computation. A | | +----------+-------------------------------------------+-----------+
| | metric of value 0 | |
| | MUST NOT be assumed | |
| | in such a case. | |
+----------+----------------------+---------------------------------+
| 6 | Check if any | Section 6 of |
| | exclude FAEMB rule | [I-D.ietf-lsr-flex-algo-bw-con] |
| | is part of the | |
| | Flex-Algorithm | |
| | definition. If | |
| | such exclude rule | |
| | exists and the link | |
| | has Maximum Link | |
| | Bandwidth | |
| | advertised, check | |
| | if the link | |
| | bandwidth satisfies | |
| | the FAEMB rule. If | |
| | the link does not | |
| | satisfy the FAEMB | |
| | rule, the link MUST | |
| | be pruned from the | |
| | Flex-Algorithm | |
| | computation | |
+----------+----------------------+---------------------------------+
| 7 | Check if any | Section 6 of |
| | exclude FAEMD rule | [I-D.ietf-lsr-flex-algo-bw-con] |
| | is part of the | |
| | Flex-Algorithm | |
| | definition. If | |
| | such exclude rule | |
| | exists and the link | |
| | has Min | |
| | Unidirectional link | |
| | delay advertised, | |
| | check if the link | |
| | delay satisfies the | |
| | FAEMD rule. If the | |
| | link does not | |
| | satisfy the FAEMD | |
| | rule, the link MUST | |
| | be pruned from the | |
| | Flex-Algorithm | |
| | computation. | |
+----------+----------------------+---------------------------------+
| 8 | Check if any | This document, Section 11 |
| | exclude reverse | |
| | Admin Group rule is | |
| | part of the Flex- | |
| | Algorithm | |
| | definition. If | |
| | such exclude rule | |
| | exists, check if | |
| | any Admin Group | |
| | that is part of the | |
| | exclude rule is | |
| | also set on the | |
| | link in the reverse | |
| | direction. If such | |
| | Admin Group is set | |
| | on the link in the | |
| | reverse direction, | |
| | the link MUST be | |
| | pruned from the | |
| | computation. | |
+----------+----------------------+---------------------------------+
| 9 | Check if any | This document, Section 11 |
| | include-any reverse | |
| | Admin Group rule is | |
| | part of the Flex- | |
| | Algorithm | |
| | definition. If | |
| | such include-any | |
| | rule exists, check | |
| | if any Admin Group | |
| | that is part of the | |
| | include-any rule is | |
| | also set on the | |
| | link in the reverse | |
| | direction. If no | |
| | such Admin Group is | |
| | set on the link in | |
| | the reverse | |
| | direction, the link | |
| | MUST be pruned from | |
| | the computation | |
+----------+----------------------+---------------------------------+
| 10 | Check if any | This document, Section 11 |
| | include-all reverse | |
| | Admin Group rule is | |
| | part of the Flex- | |
| | Algorithm | |
| | definition. If | |
| | such include-all | |
| | rule exists, check | |
| | if all Admin Groups | |
| | that are part of | |
| | the include-all | |
| | rule are also set | |
| | on the link in the | |
| | reverse direction. | |
| | If all such Admin | |
| | Groups are not set | |
| | on the link in the | |
| | reverse direction, | |
| | the link MUST be | |
| | pruned from the | |
| | computation. | |
+----------+----------------------+---------------------------------+
Table 6: IGP Flex-algo Path Calculation Rules Table 1: IGP Flex-Algorithm Path Calculation Rules
14. Security Considerations 14. Security Considerations
This document inherits security considerations from [RFC9350]. This document inherits security considerations from [RFC9350].
15. Acknowledgements 15. Normative References
TBD
16. Normative References
[I-D.ietf-lsr-flex-algo-bw-con]
Hegde, S., Britto, W., Shetty, R., Decraene, B., Psenak,
P., and T. Li, "IGP Flexible Algorithms: Bandwidth, Delay,
Metrics and Constraints", Work in Progress, Internet-
Draft, draft-ietf-lsr-flex-algo-bw-con-22, 13 February
2025, <https://datatracker.ietf.org/doc/html/draft-ietf-
lsr-flex-algo-bw-con-22>.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997, DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/info/rfc2119>. <https://www.rfc-editor.org/info/rfc2119>.
[RFC7308] Osborne, E., "Extended Administrative Groups in MPLS [RFC7308] Osborne, E., "Extended Administrative Groups in MPLS
Traffic Engineering (MPLS-TE)", RFC 7308, Traffic Engineering (MPLS-TE)", RFC 7308,
DOI 10.17487/RFC7308, July 2014, DOI 10.17487/RFC7308, July 2014,
<https://www.rfc-editor.org/info/rfc7308>. <https://www.rfc-editor.org/info/rfc7308>.
[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
May 2017, <https://www.rfc-editor.org/info/rfc8174>. May 2017, <https://www.rfc-editor.org/info/rfc8174>.
[RFC9350] Psenak, P., Ed., Hegde, S., Filsfils, C., Talaulikar, K., [RFC9350] Psenak, P., Ed., Hegde, S., Filsfils, C., Talaulikar, K.,
and A. Gulko, "IGP Flexible Algorithm", RFC 9350, and A. Gulko, "IGP Flexible Algorithm", RFC 9350,
DOI 10.17487/RFC9350, February 2023, DOI 10.17487/RFC9350, February 2023,
<https://www.rfc-editor.org/info/rfc9350>. <https://www.rfc-editor.org/info/rfc9350>.
[RFC9843] Hegde, S., Britto, W., Shetty, R., Decraene, B., Psenak,
P., and T. Li, "IGP Flexible Algorithms: Bandwidth, Delay,
Metrics, and Constraints", RFC 9843, DOI 10.17487/RFC9843,
September 2025, <https://www.rfc-editor.org/info/rfc9843>.
16. Informative References
[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>.
Acknowledgments
TBD
Authors' Addresses Authors' Addresses
Peter Psenak Peter Psenak
Cisco Systems Cisco Systems
Apollo Business Center Apollo Business Center
Mlynske nivy 43 Mlynske nivy 43
82109 Bratislava 82109 Bratislava
Slovakia Slovakia
Email: ppsenak@cisco.com Email: ppsenak@cisco.com
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