2015-11-03 2026-01-13 1-64999 Expert Review 65000-65535 Private Use Hannes Gredler (primary), Adrian Farrel (secondary) 0 Reserved 1 Node NLRI 2 Link NLRI 3 IPv4 Topology Prefix NLRI 4 IPv6 Topology Prefix NLRI 5 SR Policy Candidate Path NLRI 6 SRv6 SID NLRI 7 Stub Link NLRI 8-1100 Unassigned 1101 Not to be allocated 1102-64999 Unassigned 65000-65535 Private Use 1-199 Expert Review 200-255 Private Use Hannes Gredler (primary), Adrian Farrel (secondary) 0 Reserved 1 IS-IS Level 1 2 IS-IS Level 2 3 OSPFv2 4 Direct 5 Static configuration 6 OSPFv3 7 BGP 8 RSVP-TE 9 Segment Routing 10-199 Unassigned 200-255 Private Use Registry closed 0 Default Layer 3 Routing topology 1-31 Unassigned 32 - 2^64-1 Private use - not recorded 0-255 Reserved (not to be allocated) 256-64999 Expert Review 65000-65535 Private Use Hannes Gredler (primary), Adrian Farrel (secondary) 0-255 Reserved 256 Local Node Descriptors RFC9552, Section 5.2.1.2 257 Remote Node Descriptors RFC9552, Section 5.2.1.3 258 Link Local/Remote Identifiers RFC9552, Section 5.2.2 259 IPv4 interface address RFC9552, Section 5.2.2 260 IPv4 neighbor address RFC9552, Section 5.2.2 261 IPv6 interface address RFC9552, Section 5.2.2 262 IPv6 neighbor address RFC9552, Section 5.2.2 263 Multi-Topology Identifier RFC9552, Section 5.2.2.1 264 OSPF Route Type RFC9552, Section 5.2.3.1 265 IP Reachability Information RFC9552, Section 5.2.3.2 266 Node MSD 267 Link MSD 268-269 Unassigned 270 Remote AS Number 271 IPv4 Remote ASBR ID 272 IPv6 Remote ASBR ID 273-511 Unassigned 512 Autonomous System RFC9552, Section 5.2.1.4 513 BGP-LS Identifier (deprecated) RFC9552, Section 5.2.1.4 514 OSPF Area-ID RFC9552, Section 5.2.1.4 515 IGP Router-ID RFC9552, Section 5.2.1.4 516 BGP Router-ID 517 BGP Confederation Member 518 SRv6 SID Information 519-549 Unassigned 550 Tunnel ID 551 LSP ID 552 IPv4/6 Tunnel Head-end address 553 IPv4/6 Tunnel Tail-end address 554 SR Policy Candidate Path Descriptor 555 MPLS Local Cross Connect 556 MPLS Cross Connect Interface 557 MPLS Cross Connect FEC 558-1023 Unassigned 1024 Node Flag Bits RFC9552, Section 5.3.1.1 1025 Opaque Node Attribute RFC9552, Section 5.3.1.5 1026 Node Name RFC9552, Section 5.3.1.3 1027 IS-IS Area Identifier RFC9552, Section 5.3.1.2 1028 IPv4 Router-ID of Local Node RFC9552, Section 5.3.1.4/Section 5.3.2.1 1029 IPv6 Router-ID of Local Node RFC9552, Section 5.3.1.4/Section 5.3.2.1 1030 IPv4 Router-ID of Remote Node RFC9552, Section 5.3.2.1 1031 IPv6 Router-ID of Remote Node RFC9552, Section 5.3.2.1 1032 S-BFD Discriminators 1033 Unassigned 1034 SR Capabilities RFC9085, Section 2.1.2 1035 SR Algorithm RFC9085, Section 2.1.3 1036 SR Local Block RFC9085, Section 2.1.4 1037 SRMS Preference RFC9085, Section 2.1.5 1038 SRv6 Capabilities 1039 Flexible Algorithm Definition 1040 Flexible Algorithm Exclude-Any Affinity 1041 Flexible Algorithm Include-Any Affinity 1042 Flexible Algorithm Include-All Affinity 1043 Flexible Algorithm Definition Flags 1044 Flexible Algorithm Prefix Metric 1045 Flexible Algorithm Exclude SRLG 1046 Flexible Algorithm Unsupported 1047 IP Algorithm 1048 IP Algorithm Prefix Reachability 1049 Flexible Algorithm Exclude Minimum Bandwidth 1050 Flexible Algorithm Exclude Maximum Link Delay 1051 Flexible Algorithm Reference Bandwidth 1052 Flexible Algorithm Bandwidth Thresholds 1053 Flexible Algorithm Exclude Any Reverse Affinity 1054 Flexible Algorithm Include Any Reverse Affinity 1055 Flexible Algorithm Include All Reverse Affinity 1056 Generic Metric 1057-1087 Unassigned 1088 Administrative group (color) RFC9552, Section 5.3.2 1089 Maximum link bandwidth RFC9552, Section 5.3.2 1090 Max. reservable link bandwidth RFC9552, Section 5.3.2 1091 Unreserved bandwidth RFC9552, Section 5.3.2 1092 TE Default Metric RFC9552, Section 5.3.2.3 1093 Link Protection Type RFC9552, Section 5.3.2 1094 MPLS Protocol Mask RFC9552, Section 5.3.2.2 1095 IGP Metric RFC9552, Section 5.3.2.4 1096 Shared Risk Link Group RFC9552, Section 5.3.2.5 1097 Opaque Link Attribute RFC9552, Section 5.3.2.6 1098 Link Name RFC9552, Section 5.3.2.7 1099 Adjacency SID RFC9085, Section 2.2.1 1100 LAN Adjacency SID RFC9085, Section 2.2.2 1101 PeerNode SID 1102 PeerAdj SID 1103 PeerSet SID 1104 Unassigned 1105 RTM Capability 1106 SRv6 End.X SID 1107 IS-IS SRv6 LAN End.X SID 1108 OSPFv3 SRv6 LAN End.X SID 1109-1113 Unassigned 1114 Unidirectional Link Delay 1115 Min/Max Unidirectional Link Delay 1116 Unidirectional Delay Variation 1117 Unidirectional Link Loss 1118 Unidirectional Residual Bandwidth 1119 Unidirectional Available Bandwidth 1120 Unidirectional Utilized Bandwidth 1121 Graceful-Link-Shutdown TLV 1122 Application-Specific Link Attributes 1123-1151 Unassigned 1152 IGP Flags RFC9552, Section 5.3.3.1 1153 IGP Route Tag RFC9552, Section 5.3.3.2 1154 IGP Extended Route Tag RFC9552, Section 5.3.3.3 1155 Prefix Metric RFC9552, Section 5.3.3.4 1156 OSPF Forwarding Address RFC9552, Section 5.3.3.5 1157 Opaque Prefix Attribute RFC9552, Section 5.3.3.6 1158 Prefix-SID RFC9085, Section 2.3.1 1159 Range RFC9085, Section 2.3.5 1160 IS-IS Flood Reflection 1161 SID/Label RFC9085, Section 2.1.1 1162 SRv6 Locator 1163-1169 Unassigned 1170 Prefix Attributes Flags RFC9085, Section 2.3.2 1171 Source Router Identifier RFC9085, Section 2.3.3 1172 L2 Bundle Member Attributes RFC9085, Section 2.2.3 1173 Extended Administrative Group 1174 Source OSPF Router-ID RFC9085, Section 2.3.4 1175-1179 Unassigned 1180 SPF Capability (DEPRECATED) 1181 Sequence Number RFC9815, Section 5.2.4 1182 IPv4 Link Prefix Length (DEPRECATED) 1183 IPv6 Link Prefix Length (DEPRECATED) 1184 SPF Status RFC9815, Sections 5.2.1.1, 5.2.2.2, 5.2.3.1 1185 Address Family Link Descriptor RFC9815, Section 5.2.2.1 1186-1199 Unassigned 1200 MPLS-TE Path State 1201 SR Binding SID 1202 SR Candidate Path State 1203 SR Candidate Path Name 1204 SR Candidate Path Constraints 1205 SR Segment List 1206 SR Segment 1207 SR Segment List Metric 1208 SR Affinity Constraint 1209 SR SRLG Constraint 1210 SR Bandwidth Constraint 1211 SR Disjoint Group Constraint 1212 SRv6 Binding SID 1213 SR Policy Name 1214 SR Bidirectional Group Constraint 1215 SR Metric Constraint 1216 SR Segment List Bandwidth 1217 SR Segment List Identifier 1218-1219 Unassigned 1220 NRP 1221-1249 Unassigned 1250 SRv6 Endpoint Behavior 1251 SRv6 BGP PeerNode SID 1252 SRv6 SID Structure 1253-64999 Unassigned 65000-65535 Private Use Standards Action 0 Backup Flag (B-Flag) 1 Set Flag (S-Flag) 2 Persistent Flag (P-Flag) 3-7 Unassigned Expert Review Adrian Farrel, Hannes Gredler 0 Overload Bit (O-bit) 1 Attached Bit (A-bit) 2 External Bit (E-bit) 3 ABR Bit (B-bit) 4 Router Bit (R-bit) 5 V6 Bit (V-bit) 6-7 Unassigned Expert Review Adrian Farrel, Hannes Gredler 0 Label Distribution Protocol (L-bit) 1 Extension to RSVP for LSP Tunnels (R-bit) 2-7 Unassigned Expert Review Adrian Farrel, Hannes Gredler 0 IS-IS Up/Down Bit (D-bit) 1 OSPF "no unicast" Bit (N-bit) 2 OSPF "local address" Bit (L-bit) 3 OSPF "propagate NSSA" Bit (P-bit) 4-7 Unassigned Expert Review Matthew Bocci, Zafar Ali 0 Reserved IETF 1 Type A Segment IETF 2 Type B Segment IETF 3 Type C Segment IETF 4 Type D Segment IETF 5 Type E Segment IETF 6 Type F Segment IETF 7 Type G Segment IETF 8 Type H Segment IETF 9 Type I Segment IETF 10 Type J Segment IETF 11 Type K Segment IETF 12-255 Unassigned Expert Review Stephane Litkowski, Jie Dong 0 IGP IETF 1 Min Unidirectional Delay IETF 2 TE IETF 3 Hop Count IETF 4 SID List Length IETF 5 Bandwidth IETF 6 Avg Unidirectional Delay IETF 7 Unidirectional Delay Variation IETF 8 Loss IETF 9-127 Unassigned 128-255 User Defined IETF