2007-04-25 2026-03-05 Please also see: Standards Action 0x01 MT-bit 0x02 E-bit 0x04 MC-bit 0x08 N/P-bit 0x10 L-bit 0x20 DC-bit 0x40 O-bit 0x80 DN-bit 1-127 Standards Action 128-255 Reserved 0 Reserved 1 Hello 2 Database Description 3 Link State Request 4 Link State Update 5 Link State Ack 6-127 Unassigned 128-255 Reserved 1-127 Standards Action 128-255 Reserved 0 Reserved 1 Router-LSA 2 Network-LSA 3 Summary-LSA (IP network) 4 Summary-LSA (ASBR) 5 AS-external-LSA 6 Group-membership-LSA 7 NSSA AS-external LSA 8 Reserved 9 Link-scoped Opaque LSA 10 Area-scoped Opaque LSA 11 AS-scoped Opaque LSA 12-127 Unassigned 128-255 Reserved 1-127 Standards Action 128-255 Reserved 0 Reserved 1 Point-to-Point connection to another router 2 Transit Network 3 Stub Network 4 Virtual Link Standards Action 0x01 B-bit 0x02 E-bit 0x04 V-bit 0x08 W-bit 0x10 Nt-bit 0x80 Host (H-bit) 1-255 Standards Action 256-65519 Reserved IANA does not assign 65520-65527 Experimentation IANA does not assign 65528-65535 Vendor Private Use IANA does not assign 0 Reserved 1 Grace Period 2 Graceful Restart reason 3 IP Interface Address 4-255 Unassigned 256-65519 Reserved 65520-65527 Experimentation 65528-65535 Vendor Private Use Moved to per . Standards Action 0 Base IPv4 Unicast Instance 1 Base IPv4 Multicast Instance 2 Base IPv4 In-band Management Instance 3-127 Private Use 128-255 Unassigned IETF Review or IESG Approval 0 Reserved 1 OSPFv2 Extended Prefix TLV 2 OSPF Extended Prefix Range TLV 3-32767 Unassigned 32768-33023 Reserved for Experimental Use 33024-65535 Reserved IETF Review or IESG Approval 0 Reserved 1 SID/Label Sub-TLV 2 Prefix-SID Sub-TLV 3 Flexible Algorithm Prefix Metric (FAPM) RFC9350, Section 9 4 Prefix Source OSPF Router-ID 5 Prefix Source Router Address 6 OSPFv2 IP Algorithm Prefix Reachability RFC9502, Section 6.3 7 OSPFv2 IP Forwarding Address RFC9502, Section 6.3.1 8 Unassigned 9 BIER Sub-TLV 10 BIER MPLS Encapsulation Sub-TLV 11 OSPFv2 Prefix Extended Flags 12 BIER PHP Request 13 Administrative Tag 14-32767 Unassigned 32768-33023 Reserved for Experimental Use 33024-65535 Reserved IETF Review or IESG Approval 0x80 A 0x40 N 0x20 E-Flag (ELC Flag) 0x10 AC-Flag (Anycast Flag) IETF Review or IESG Approval 0 Reserved 1 OSPFv2 Extended Link TLV 2-32767 Unassigned 32768-33023 Reserved for Experimental Use 33024-65535 Reserved IETF Review or IESG Approval The "L2BM" column indicates applicability to the L2 Bundle Attributes Member sub-TLV. The options for the "L2BM" column are: Y - This sub-TLV MAY appear in the L2 Bundle Member Attributes sub-TLV. N - This sub-TLV MUST NOT appear in the L2 Bundle Member Attributes sub-TLV. 0 Reserved 1 SID/Label Sub-TLV N 2 Adj-SID Sub-TLV Y 3 LAN Adj-SID/Label Sub-TLV Y 4 Network-to-Router Metric Sub-TLV N 5 RTM Capability N 6 OSPFv2 Link MSD N 7 Graceful-Link-Shutdown Sub-TLV N 8 Remote IPv4 Address Sub-TLV N 9 Local/Remote Interface ID Sub-TLV N 10 Application-Specific Link Attributes Y 11 Shared Risk Link Group Y 12 Unidirectional Link Delay Y 13 Min/Max Unidirectional Link Delay Y 14 Unidirectional Delay Variation Y 15 Unidirectional Link Loss Y 16 Unidirectional Residual Bandwidth Y 17 Unidirectional Available Bandwidth Y 18 Unidirectional Utilized Bandwidth Y 19 Administrative Group Y 20 Extended Administrative Group Y 21 OSPFv2 Link Attributes Bits Y 22 TE Metric Y 23 Maximum link bandwidth Y 24 L2 Bundle Member Attributes N 25 Generic Metric Y RFC9843, Section 2.2 26-32767 Unassigned 32768-33023 Reserved for Experimental Use 33024-65535 Reserved IETF Review or IESG Approval 0 Reserved 1 Extended Inter-Area ASBR 2-32767 Unassigned 32768-33023 Reserved for Experimental Use 33024-65535 Reserved IETF Review or IESG Approval 0 Reserved 1 OSPF Flexible Algorithm ASBR Metric 2 OSPF IP Flexible Algorithm ASBR Metric RFC9502, Section 6.5 3-32767 Unassigned 32768-33023 Reserved for Experimental Use 33024-65535 Reserved IETF Review or IESG Approval 0 bit E RFC9502, Section 6.3 1-7 Unassigned IETF Review Per , IANA will add subsequent blocks of 32 bits upon exhaustion of the preceding 32-bit block. 0 U-Flag RFC9929, Section 4.2 1 UP-Flag RFC9929, Section 4.2 2-31 Unassigned