Value,Code,Reference
0,Reserved,
1,ORIGIN,[RFC4271]
2,AS_PATH,[RFC4271]
3,NEXT_HOP,[RFC4271]
4,MULTI_EXIT_DISC,[RFC4271]
5,LOCAL_PREF,[RFC4271]
6,ATOMIC_AGGREGATE,[RFC4271]
7,AGGREGATOR,[RFC4271]
8,COMMUNITIES,[RFC1997]
9,ORIGINATOR_ID,[RFC4456]
10,CLUSTER_LIST,[RFC4456]
11,DPA (deprecated),"[Chen, E., Bates, T., ""Destination Preference Attribute for BGP"",
Work in progress, March 1996.][RFC6938]"
12,ADVERTISER  (historic) (deprecated),[RFC1863][RFC4223][RFC6938]
13,RCID_PATH / CLUSTER_ID (Historic) (deprecated),[RFC1863][RFC4223][RFC6938]
14,MP_REACH_NLRI,[RFC4760]
15,MP_UNREACH_NLRI,[RFC4760]
16,EXTENDED COMMUNITIES,[Eric_Rosen][draft-ramachandra-bgp-ext-communities-00][RFC4360]
17,AS4_PATH,[RFC6793]
18,AS4_AGGREGATOR,[RFC6793]
19,SAFI Specific Attribute (SSA) (deprecated),[Gargi_Nalawade][draft-kapoor-nalawade-idr-bgp-ssa-00][draft-nalawade-idr-mdt-safi-00][draft-wijnands-mt-discovery-00]
20,Connector Attribute (deprecated),[RFC6037]
21,AS_PATHLIMIT (deprecated),[draft-ietf-idr-as-pathlimit-02]
22,PMSI_TUNNEL,[RFC6514]
23,Tunnel Encapsulation,[RFC9012]
24,Traffic Engineering,[RFC5543]
25,IPv6 Address Specific Extended Community,[RFC5701]
26,AIGP,[RFC7311]
27,PE Distinguisher Labels,[RFC6514]
28,BGP Entropy Label Capability Attribute (deprecated),[RFC6790][RFC7447]
29,BGP-LS Attribute,[RFC9552]
30,Deprecated,[RFC8093]
31,Deprecated,[RFC8093]
32,LARGE_COMMUNITY,[RFC8092]
33,BGPsec_Path,[RFC8205]
34,"BGP Community Container Attribute (TEMPORARY - registered 2017-07-28, extension registered 2024-08-22, expires 2025-07-28)",[draft-ietf-idr-wide-bgp-communities-11]
35,Only to Customer (OTC),[RFC9234]
36,"BGP Domain Path (D-PATH) (TEMPORARY - registered 2019-07-08, extension registered 2025-06-06, expires 2026-07-08)",[draft-ietf-bess-evpn-ipvpn-interworking-10]
37,SFP attribute,[RFC9015]
38,BFD Discriminator,[RFC9026]
39,"BGP Next Hop Dependent Capabilities (NHC) (TEMPORARY - registered 2022-12-20, extension registered 2024-12-10, expires 2025-12-20)",[draft-ietf-idr-entropy-label-13]
40,BGP Prefix-SID,[RFC8669]
41,BIER,[RFC9793]
42,"Edge Metadata Path Attribute (TEMPORARY - registered 2025-04-23, expires 2026-04-23)",[draft-ietf-idr-5g-edge-service-metadata-27]
43-127,Unassigned,
128,ATTR_SET,[RFC6368]
129,Deprecated,[RFC8093]
130-240,Unassigned,
241,Deprecated,[RFC8093]
242,Deprecated,[RFC8093]
243,Deprecated,[RFC8093]
244-254,Unassigned,
255,Reserved for development,[RFC2042]