Interior Gateway Protocol (IGP) Parameters

Created: 2017-12-18
Last Updated: 2025-08-08
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Registries Included Below

IGP Algorithm Types

Registration Procedure(s)

Standards Action

Reference

[RFC8665]

Available Formats

CSV

Value	Description	Reference
0	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.	[RFC8665]
1	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.	[RFC8665]
2-127	Unassigned
128-255	Flexible Algorithms	[RFC9350, Section 4]

IGP MSD-Types

Registration Procedure(s)

Expert Review

Expert(s)

Uma Chunduri, Jeff Tantsura

Reference

[RFC8491][RFC9702]

Note

When this registry is modified, the YANG module "iana-msd-type" 
must be updated as defined in [RFC9702].

Available Formats

CSV

Value	Name	Data Plane	Reference
0	Reserved		[RFC8491]
1	Base MPLS Imposition MSD	MPLS	[RFC8491]
2	ERLD-MSD	MPLS	[RFC9088]
3	Readable Label Depth	MPLS	[RFC9789]
4-40	Unassigned
41	SRH Max SL	SRv6	[RFC9352]
42	SRH Max End Pop	SRv6	[RFC9352]
43	Unassigned
44	SRH Max H.encaps	SRv6	[RFC9352]
45	SRH Max End D	SRv6	[RFC9352]
46-250	Unassigned
251-254	Experimental Use		[RFC8491]
255	Reserved		[RFC8491]

Link Attribute Application Identifiers

Registration Procedure(s)

Expert Review

Expert(s)

Les Ginsberg, Chris Hopps

Reference

[RFC9479]

Available Formats

CSV

Bit	Name	Reference
0	RSVP-TE (R-bit)	[RFC9479]
1	Segment Routing Policy (S-bit)	[RFC9479]
2	Loop-Free Alternate (F-bit)	[RFC9479]
3	Flexible Algorithm (X-bit)	[RFC9350, Section 12]
4-63	Unassigned

IGP Metric-Type

Registration Procedure(s)

Standards Action

Reference

[RFC9350][RFC-ietf-lsr-flex-algo-bw-con-22]

Available Formats

CSV

Type	Description	Reference	Allowed in Generic-Metric
0	IGP Metric	[RFC9350, Section 5.1]	No
1	Min Unidirectional Link Delay as defined in [RFC8570, Section 4.2] and [RFC7471, Section 4.2]	[RFC9350, Section 5.1]	No
2	Traffic Engineering Default Metric as defined in [RFC5305, Section 3.7] and Traffic Engineering Metric as defined in [RFC3630, Section 2.5.5]	[RFC9350, Section 5.1]	No
3	Bandwidth Metric	[RFC-ietf-lsr-flex-algo-bw-con-22]	Yes
4-127	Unassigned
128-255	User-defined metric	[RFC-ietf-lsr-flex-algo-bw-con-22]	Yes

IGP Flexible Algorithm Definition Flags

Registration Procedure(s)

Standards Action

Reference

[RFC9350]

Available Formats

CSV

Bit	Name	Reference
0	Prefix Metric Flag (M-flag)	[RFC9350, Sections 6.4 and 7.4]

Path Computation Element (PCE) Capability Flags

Registration Procedure(s)

IETF Review

Reference

[RFC9353]

Available Formats

CSV

Bit	Capability Description	Reference
0	Path computation with GMPLS link constraints	[RFC5088]
1	Bidirectional path computation	[RFC5088]
2	Diverse path computation	[RFC5088]
3	Load-balanced path computation	[RFC5088]
4	Synchronized paths computation	[RFC5088]
5	Support for multiple objective functions	[RFC5088]
6	Support for additive path constraints (max hop count, etc.)	[RFC5088]
7	Support for request prioritization	[RFC5088]
8	Support for multiple requests per message	[RFC5088]
9	Global Concurrent Optimization (GCO)	[RFC5557]
10	P2MP path computation	[RFC8306]
11	Active stateful PCE capability	[RFC8231]
12	Passive stateful PCE capability	[RFC8231]
13	Active Stateful PCE with P2MP	[RFC8623]
14	Passive Stateful PCE with P2MP	[RFC8623]
15	Stateful PCE Initiation with P2MP	[RFC8623]
16	FlowSpec	[RFC9168]
17	TCP-AO Support	[RFC9353]
18	PCEP over TLS support	[RFC9353]
19-31	Unassigned

PCE Discovery (PCED) Sub-TLV Type Indicators

Registration Procedure(s)

Standards Action

Reference

[RFC9353]

Available Formats

CSV

Value	Description	Reference
0	Reserved	[RFC9353][RFC5088]
1	PCE-ADDRESS	[RFC9353][RFC5088]
2	PATH-SCOPE	[RFC9353][RFC5088]
3	PCE-DOMAIN	[RFC9353][RFC5088]
4	NEIG-PCE-DOMAIN	[RFC9353][RFC5088]
5	PCE-CAP-FLAGS	[RFC9353][RFC5088]
6	KEY-ID	[RFC9353]
7	KEY-CHAIN-NAME	[RFC9353]
8-65535	Unassigned

IGP Algorithm Type For Computing Flooding Topology

Registration Procedure(s)

Expert Review

Expert(s)

Unassigned

Reference

[RFC-ietf-lsr-dynamic-flooding-18]

Available Formats

CSV

Value	Description	Reference
0	Reserved for centralized mode	[RFC-ietf-lsr-dynamic-flooding-18]
1-127	Unassigned
128-254	Reserved for Private Use	[RFC-ietf-lsr-dynamic-flooding-18]
255	Reserved	[RFC-ietf-lsr-dynamic-flooding-18]

IGP Flex-Algorithm Path Computation Rules

Registration Procedure(s)

Expert Review

Expert(s)

Unassigned

Reference

[RFC-ietf-lsr-igp-flex-algo-reverse-affinity-12]

Available Formats

CSV

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.	[RFC9350, 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.	[RFC9350, 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.	[RFC9350, 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.	[RFC9350, Section 13]
5	If the Flex-Algorithm Definition uses something other than the IGP metric (Section 5 of [RFC9350]), 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.	[RFC9350, 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-ietf-lsr-flex-algo-bw-con-22, 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-ietf-lsr-flex-algo-bw-con-22, 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-ietf-lsr-igp-flex-algo-reverse-affinity-12, 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-ietf-lsr-igp-flex-algo-reverse-affinity-12, 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-ietf-lsr-igp-flex-algo-reverse-affinity-12, Section 11]