Interior Gateway Protocol (IGP) Parameters

Created

  • 2017-12-18

Last Updated

  • 2026-09-18

Available Formats

IGP Algorithm Types

Registration Procedure(s)

  • Standards Action

Reference

Note

When this registry is modified, the YANG module iana-igp-algo-types must be updated as defined in RFC-ietf-lsr-ospf-flex-algo-yang-16.

Available Formats

Value Name Description Reference
0 SPF Shortest Path First (SPF) algorithm based on link metric. This is the standard shortest path algorithm as computed by the IGP protocol. Consistent with the deployed practice for link-state protocols, Algorithm 0 permits any node to overwrite the SPF path with a different path based on its local policy. RFC 8665
1 Strict SPF Strict Shortest Path First (SPF) algorithm based on link metric. The algorithm is identical to Algorithm 0 but Algorithm 1 requires that all nodes along the path will honor the SPF routing decision. Local policy at the node claiming support for Algorithm 1 MUST NOT alter the SPF paths computed by Algorithm 1. RFC 8665
2-127 Unassigned
128-255 Flexible Algorithms RFC 9350, Section 4

IGP MSD-Types

Registration Procedure(s)

  • Expert Review

Expert(s)

  • Uma Chunduri, Jeff Tantsura

Reference

  • RFC 8491: Signaling Maximum SID Depth (MSD) Using IS-IS
  • RFC 9702: YANG Data Model for Maximum Segment Identifier (SID) Depth (MSD) Types and MPLS MSD

Note

When this registry is modified, the YANG module iana-msd-types must be updated as defined in RFC 9702.

Available Formats

Value Name Data Plane Reference
0 Reserved RFC 8491
1 Base MPLS Imposition MSD MPLS RFC 8491
2 ERLD-MSD MPLS RFC 9088
3 Readable Label Depth MPLS RFC 9789; RFC-ietf-mpls-mna-ps-hdr-19
4-40 Unassigned
41 SRH Max SL SRv6 RFC 9352
42 SRH Max End Pop SRv6 RFC 9352
43 Unassigned
44 SRH Max H.encaps SRv6 RFC 9352
45 SRH Max End D SRv6 RFC 9352
46-250 Unassigned
251-254 Experimental Use RFC 8491
255 Reserved RFC 8491

IGP Metric-Type

Reference

Note

When this registry is modified, the YANG module iana-igp-metric-types must be updated as defined in RFC-ietf-lsr-ospf-flex-algo-yang-16.

Available Formats

Range Registration Procedures
0-127 Standards Action
128-255 User-Defined Metric
Type Name Description Reference Allowed in Generic-Metric
0 IGP Metric IGP Metric RFC 9350, Section 5.1 No
1 Min Unidirectional Link Delay Min Unidirectional Link Delay as defined in RFC 8570, Section 4.2 and RFC 7471, Section 4.2 RFC 9350, Section 5.1 No
2 TE Default Metric Traffic Engineering Default Metric as defined in RFC 5305, Section 3.7 and Traffic Engineering Metric as defined in RFC 3630, Section 2.5.5 RFC 9350, Section 5.1 No
3 Bandwidth Metric Bandwidth Metric RFC 9843 Yes
4-127 Unassigned
128-255 Reserved for User-Defined Metric RFC 9843 Yes

IGP Flexible Algorithm Definition Flags

Registration Procedure(s)

  • Standards Action

Reference

Available Formats

Bit Name Reference
0 Prefix Metric Flag (M-flag) RFC 9350, Section 6.4, 7.4

Path Computation Element (PCE) Capability Flags

Registration Procedure(s)

  • IETF Review

Reference

  • RFC 9353: IGP Extension for Path Computation Element Communication Protocol (PCEP) Security Capability Support in PCE Discovery (PCED)

Available Formats

Bit Capability Description Reference
0 Path computation with GMPLS link constraints RFC 5088
1 Bidirectional path computation RFC 5088
2 Diverse path computation RFC 5088
3 Load-balanced path computation RFC 5088
4 Synchronized paths computation RFC 5088
5 Support for multiple objective functions RFC 5088
6 Support for additive path constraints (max hop count, etc.) RFC 5088
7 Support for request prioritization RFC 5088
8 Support for multiple requests per message RFC 5088
9 Global Concurrent Optimization (GCO) RFC 5557
10 P2MP path computation RFC 8306
11 Active stateful PCE capability RFC 8231
12 Passive stateful PCE capability RFC 8231
13 Active Stateful PCE with P2MP RFC 8623
14 Passive Stateful PCE with P2MP RFC 8623
15 Stateful PCE Initiation with P2MP RFC 8623
16 FlowSpec RFC 9168
17 TCP-AO Support RFC 9353
18 PCEP over TLS support RFC 9353
19-31 Unassigned

PCE Discovery (PCED) Sub-TLV Type Indicators

Registration Procedure(s)

  • Standards Action

Reference

  • RFC 9353: IGP Extension for Path Computation Element Communication Protocol (PCEP) Security Capability Support in PCE Discovery (PCED)

Available Formats

Value Description Reference
0 Reserved RFC 9353; RFC 5088
1 PCE-ADDRESS RFC 9353; RFC 5088
2 PATH-SCOPE RFC 9353; RFC 5088
3 PCE-DOMAIN RFC 9353; RFC 5088
4 NEIG-PCE-DOMAIN RFC 9353; RFC 5088
5 PCE-CAP-FLAGS RFC 9353; RFC 5088
6 KEY-ID RFC 9353
7 KEY-CHAIN-NAME RFC 9353
8-65535 Unassigned

IGP Algorithm Type For Computing Flooding Topology

Registration Procedure(s)

  • Expert Review

Expert(s)

  • Peter Psenak, Tony Li

Reference

  • RFC 9667: Dynamic Flooding on Dense Graphs

Available Formats

Value Description Reference
0 Reserved for centralized mode RFC 9667
1 Modified MANET Reduction draft-ietf-lsr-distoptflood-13
2-127 Unassigned
128-254 Reserved for Private Use RFC 9667
255 Reserved RFC 9667

IGP Flex-Algorithm Path Computation Rules

Registration Procedure(s)

  • Expert Review

Expert(s)

  • Peter Psenak, Shraddha Hegde

Reference

  • RFC 9917: IGP Flexible Algorithms Reverse Affinity Constraint

Available Formats

Sequence Number Description Reference
1 Check if any exclude Administrative Group rule is part of the Flex-Algorithm Definition. If such exclude rule exists, check if any color that is part of the exclude rule is also set on the link. If such a color is set, the link MUST be pruned from the computation. RFC 9350, Section 13
2 Check if any exclude SRLG rule is part of the Flex-Algorithm Definition. If such exclude rule exists, check if the link is part of any SRLG that is also part of the SRLG exclude rule. If the link is part of such SRLG, the link MUST be pruned from the computation. RFC 9350, Section 13
3 Check if any include-any Administrative Group rule is part of the Flex-Algorithm Definition. If such include-any rule exists, check if any color that is part of the include-any rule is also set on the link. If no such color is set, the link MUST be pruned from the computation. RFC 9350, Section 13
4 Check if any include-all Administrative Group rule is part of the Flex-Algorithm Definition. If such include-all rule exists, check if all colors that are part of the include-all rule are also set on the link. If all such colors are not set on the link, the link MUST be pruned from the computation. RFC 9350, Section 13
5 If the Flex-Algorithm Definition uses something other than the IGP metric (Section 5 of RFC 9350), and such metric is not advertised for the particular link in a topology for which the computation is done, such link MUST be pruned from the computation. A metric of value 0 MUST NOT be assumed in such a case. RFC 9350, Section 13
6 Check if any exclude FAEMB rule 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. RFC 9843, Section 6
7 Check if any exclude FAEMD rule 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. RFC 9843, Section 6
8 Check if any 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. RFC 9917, Section 11
9 Check if any 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. RFC 9917, Section 11
10 Check if any 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. RFC 9917, Section 11