2026-04-03 Standards Action 0 Reserved 1 OPEN 2 UPDATE 3 NOTIFICATION 4 KEEPALIVE 5 ROUTE-REFRESH 6-255 Unassigned Standards Action 0 Reserved 1 ORIGIN 2 AS_PATH 3 NEXT_HOP 4 MULTI_EXIT_DISC 5 LOCAL_PREF 6 ATOMIC_AGGREGATE 7 AGGREGATOR 8 COMMUNITIES 9 ORIGINATOR_ID 10 CLUSTER_LIST 11 DPA (deprecated) Chen, E., Bates, T., "Destination Preference Attribute for BGP", Work in progress, March 1996. 12 ADVERTISER (historic) (deprecated) 13 RCID_PATH / CLUSTER_ID (Historic) (deprecated) 14 MP_REACH_NLRI 15 MP_UNREACH_NLRI 16 EXTENDED COMMUNITIES 17 AS4_PATH 18 AS4_AGGREGATOR 19 SAFI Specific Attribute (SSA) (deprecated) 20 Connector Attribute (deprecated) 21 AS_PATHLIMIT (deprecated) 22 PMSI_TUNNEL 23 Tunnel Encapsulation 24 Traffic Engineering 25 IPv6 Address Specific Extended Community 26 AIGP 27 PE Distinguisher Labels 28 BGP Entropy Label Capability Attribute (deprecated) 29 BGP-LS Attribute 30 Deprecated 31 Deprecated 32 LARGE_COMMUNITY 33 BGPsec_Path 34 BGP Community Container Attribute (TEMPORARY - registered 2017-07-28, extension registered 2024-08-22, expires 2025-07-28) 35 Only to Customer (OTC) 36 BGP Domain Path (D-PATH) 37 SFP attribute 38 BFD Discriminator 39 BGP Next Hop Dependent Characteristic (NHC) (TEMPORARY - registered 2022-12-20, extension registered 2025-11-24, expires 2026-12-20) 40 BGP Prefix-SID 41 BIER 42 Edge Metadata Path Attribute (TEMPORARY - registered 2025-04-23, extension registered 2026-04-03, expires 2027-04-23) 43-127 Unassigned 128 ATTR_SET 129 Deprecated 130-240 Unassigned 241 Deprecated 242 Deprecated 243 Deprecated 244-254 Unassigned 255 Reserved for development Standards Action 0 Reserved 1 Message Header Error 2 OPEN Message Error 3 UPDATE Message Error 4 Hold Timer Expired 5 Finite State Machine Error 6 Cease 7 ROUTE-REFRESH Message Error 8 Send Hold Timer Expired 9 Loss of LSDB Synchronization 10-255 Unassigned Standards Action Standards Action 0 Unspecific 1 Connection Not Synchronized 2 Bad Message Length 3 Bad Message Type 4-255 Unassigned Standards Action 0 Unspecific 1 Unsupported Version Number 2 Bad Peer AS 3 Bad BGP Identifier 4 Unsupported Optional Parameter 5 [Deprecated] 6 Unacceptable Hold Time 7 Unsupported Capability 8 Deprecated 9 Deprecated 10 Deprecated 11 Role Mismatch 12-255 Unassigned Standards Action 0 Unspecific 1 Malformed Attribute List 2 Unrecognized Well-known Attribute 3 Missing Well-known Attribute 4 Attribute Flags Error 5 Attribute Length Error 6 Invalid ORIGIN Attribute 7 [Deprecated] 8 Invalid NEXT_HOP Attribute 9 Optional Attribute Error 10 Invalid Network Field 11 Malformed AS_PATH 12-255 Unassigned Standards Action 0 Unspecified Error 1 Receive Unexpected Message in OpenSent State 2 Receive Unexpected Message in OpenConfirm State 3 Receive Unexpected Message in Established State 4-255 Unassigned Standards Action or Early IANA Allocation process 0 Reserved 1 Maximum Number of Prefixes Reached 2 Administrative Shutdown 3 Peer De-configured 4 Administrative Reset 5 Connection Rejected 6 Other Configuration Change 7 Connection Collision Resolution 8 Out of Resources 9 Hard Reset 10 BFD Down 11-255 Unassigned 0-127 Standards Action 128-255 First Come First Served 0 Reserved 1 Invalid Message Length 2-255 Unassigned 0-63 Standards Action 64-127 First Come First Served 128-255 Vendor-Specific IANA does not assign 0 Reserved 1-63 Unassigned 64 Address Prefix ORF 65 CP-ORF 66 VPN Prefix ORF 67-127 Unassigned 128-255 Reserved for Vendor-Specific IETF Review 0 Reserved 1 Authentication (deprecated) 2 Capabilities 3-254 Unassigned 255 Extended Length Moved to per . Moved to per . When this registry is modified, the YANG module iana-bgp-l2-encaps must be updated as defined in . 0-127 Expert Review 128-251 First Come First Served 252-255 Experimental Use 0 Reserved 1 Frame Relay 2 ATM AAL5 SDU VCC transport 3 ATM transparent cell transport 4 Ethernet (VLAN) Tagged Mode 5 Ethernet Raw Mode 6 Cisco HDLC 7 PPP 8 SONET/SDH Circuit Emulation Service 9 ATM n-to-one VCC cell transport 10 ATM n-to-one VPC cell transport 11 IP Layer 2 Transport 12-14 Unassigned 15 Frame Relay Port mode 16 Unassigned 17 Structure-agnostic E1 over packet 18 Structure-agnostic T1 (DS1) over packet 19 VPLS 20 Structure-agnostic T3 (DS3) over packet 21 Nx64kbit/s Basic Service using Structure-aware 22-24 Unassigned 25 Frame Relay DLCI 25-39 Unassigned 40 Structure-agnostic E3 over packet 41 Octet-aligned payload for Structure-agnostic DS1 circuits 42 E1 Nx64kbit/s with CAS using Structure-aware 43 DS1 (ESF) Nx64kbit/s with CAS using Structure-aware 44 DS1 (SF) Nx64kbit/s with CAS using Structure-aware 45-127 Unassigned 128-251 Unassigned 252-255 Experimental Use 0-127 Expert Review 128-251 First Come First Served 252-255 Experimental Use 0 Reserved 1 Circuit Status Vector 2-127 Unassigned 128-251 Unassigned 252-255 Experimental Use Standards Action 0 Reserved 1 AIGP 2-255 Unassigned 0-127 Standards Action 128-254 First Come First Served 0 Route-Refresh 1 BoRR 2 EoRR 3-254 Unassigned 255 Reserved 0x00-0x7A IETF Review 0x7B-0x7E Experimental Use 0x80-0xFA Composite Tunnel 0xFB-0xFE Experimental Use 0xFF Standards Action The status of value 0xFF may only be changed through Standards Action . 0x00 no tunnel information present 0x01 RSVP-TE P2MP LSP 0x02 mLDP P2MP LSP 0x03 PIM-SSM Tree 0x04 PIM-SM Tree 0x05 BIDIR-PIM Tree 0x06 Ingress Replication 0x07 mLDP MP2MP LSP 0x08 Transport Tunnel 0x09 Unassigned 0x0A Assisted Replication Tunnel 0x0B BIER 0x0C SR-MPLS P2MP Tree 0x0D SRv6 P2MP Tree 0x0E-0x7A Unassigned 0x7B-0x7E Reserved for Experimental Use 0x7F Reserved 0x80-0xFA Reserved for Composite Tunnel 0xFB-0xFE Reserved for Experimental Use 0xFF wildcard transport tunnel type Standards Action 0 Unassigned 1 Extension 2 Leaf Information Required per-Flow (LIR-pF) 3-4 Assisted Replication Type (T) 5 Broadcast and Multicast (BM) 6 Unknown (U) 7 Leaf Information Required (L) Standards Action Values may be assigned from one of several ranges: - Range 0x01-0x3f: Generic/PIM Range. Values are assigned from this range when the NLRI format associated with the route type presupposes that PIM or IGMP is the C-multicast control protocol, or when the NLRI format associated with the route type is independent of the C-multicast control protocol. - Range 0x43-0x7f: mLDP Range. Values are assigned from this range when the NLRI format associated with the route type presupposes that mLDP is the C-multicast control protocol. - Range 0x80-0xff: This range is reserved; values should not be assigned from this range. In general, whenever an assignment is requested from this registry, two codepoints should be requested at the same time: one from the Generic/PIM range (0x01-0x3f) and one from the mLDP range (0x43-0x7f). The two codepoints should have the same low-order 6 bits. If one of the two codepoints is not actually needed, it should be registered anyway, and marked as "Reserved." 0x00 Reserved 0x01 Intra-AS I-PMSI A-D route 0x02 Inter-AS I-PMSI A-D route 0x03 S-PMSI A-D route 0x04 Leaf A-D route 0x05 Source Active A-D route 0x06 Shared Tree Join route 0x07 Source Tree Join route 0x08-0x3f Unassigned (Generic/PIM range) 0x40-0x42 Reserved 0x43 S-PMSI A-D route for C-multicast mLDP 0x44 Leaf A-D route for C-multicast mLDP 0x45-0x46 Reserved 0x47 Source Tree Join route for C-multicast mLDP 0x48-0x7f Unassigned (mLDP range) 0x80-0xff Reserved Expert Review Acee Lindem, Hannes Gredler 0 Reserved 1 Label-Index 2 Deprecated 3 Originator SRGB 4 Deprecated 5 SRv6 L3 Service TLV 6 SRv6 L2 Service TLV 7 SRv6 Transport TLV 8-254 Unassigned 255 Reserved Expert Review Acee Lindem, Hannes Gredler 0x0001-0x8000 Unassigned Expert Review Acee Lindem, Hannes Gredler 0x0001-0x8000 Unassigned Standards Action 0 Restart State R 1 Notification N 2-3 Unassigned Standards Action 0 Forwarding State F 1-7 Unassigned First Come First Served 0 Reserved 1 Association TLV 2020-09-02 2 Hop TLV 2020-09-02 3 SFT TLV 2020-09-02 4 MPLS Swapping/Stacking 2020-09-02 5 SFP Traversal With MPLS 2020-09-02 6-65534 Unassigned 65535 Reserved First Come First Served 0 Reserved 1 Bidirectional SFP 2020-09-02 2-65534 Unassigned 65535 Reserved Standards Action 0 NSH data plane 1 MPLS data plane 2-15 Unassigned 0-175 IETF Review 176-249 First Come First Served 250-254 Experimental Use 255 IETF Review 0 Reserved 1 P2MP BFD Session 2-175 Unassigned 176 S-BFD for SRv6 Locator Session 177 S-BFD for Common Session 178-249 Unassigned 250-254 Experimental Use 255 Reserved 0-175 IETF Review 176-249 First Come First Served 250-254 Experimental Use 255 IETF Review 0 Reserved 1 Source IP Address 2-175 Unassigned 176-249 Unassigned 250-254 Experimental Use 255 Reserved 0-127 IETF Review 128-254 First Come First Served 255 IETF Review 0 Reserved 1 SRv6 SID Information Sub-TLV 2-254 Unassigned 255 Reserved 0-127 IETF Review 128-254 First Come First Served 255 IETF Review 0 Reserved 1 SRv6 SID Structure Sub-Sub-TLV 2-254 Unassigned 255 Reserved IETF Review 0-7 Unassigned Standards Action 0 Preservation of state F 1-7 Unassigned First Come First Served 0 Reserved 1 BIER TLV 2 MPLS Encapsulation sub-TLV 3 non-MPLS Encapsulation sub-TLV 4 BIER Nexthop sub-TLV 5 BIER PHP Request 6-65535 Unassigned Specification Required Bruno Decraene, Swadesh Agrawal 0 Reserved 1 Color-Aware Route 2 IP Prefix 3-255 Unassigned Specification Required Bruno Decraene, Swadesh Agrawal 0 Reserved 1 Label 2 Label-Index 3 SRv6 SID 4-64 Unassigned Eric Rosen mailto:erosen&cisco.com 2010-02-23 Gargi Nalawade mailto:gargi&cisco.com 2004-02