A BGP community is a tag a network attaches to a route announcement so that another network can act on it: lower the route’s preference, prepend to certain peers, keep it inside a region, or drop traffic to it. Each provider defines its own values and publishes them for its customers. The guides below collect those definitions in one place, one page per provider.

These guides are for CUSTOMER use only. A community only works on a network you buy transit from, directly or through your upstream. If neither you nor your upstream is a customer of the provider, the values on its page will do nothing for you.

The three kinds

Standard communities (RFC 1997) are 32 bits written as two 16-bit numbers, by convention the provider’s AS number and a value: 3356:70. They cannot carry a 4-byte AS number, which is why the other two exist. Extended communities (RFC 4360) are 64 bits with a type field; they carry route targets for VPNs and the few provider controls that need a 4-byte AS. Large communities (RFC 8092) are three 32-bit numbers, written AS:function:value, and are the right choice for any network with a 4-byte AS number or a scheme that has outgrown 16-bit values.

Four well-known values mean the same thing everywhere: NO_EXPORT (65535:65281) keeps a route inside the receiving AS, NO_ADVERTISE (65535:65282) keeps it on the receiving router, NO_EXPORT_SUBCONFED (65535:65283) keeps it inside a confederation member, and BLACKHOLE (65535:666, RFC 7999) asks the receiving network to drop traffic to the prefix.

How to use a provider’s guide

Find the control you want in the provider’s table, then read the surrounding text for the conditions: many values apply only to specific prefixes, specific regions or specific sessions. Test the community on one prefix during a quiet period and confirm the effect in the provider’s looking glass before you depend on it during an outage. Values change, so treat a guide as a starting point: your provider’s own documentation is the final word.

Keeping the guides current

Many of the guides are checked automatically against the provider’s published routing registry object. Where a provider publishes only a document or a web page, we check by hand. If a value is wrong, a guide is missing, or your network would like its communities listed, tell us at bgp-guide (at) onestep.net.

Network AS Network Name
AS 174 Cogent Communications
AS 209 Lumen Technologies
AS 513 CERN – European Organization for Nuclear Research
AS 577 Bell Canada
AS 701 Verizon
AS 1239 Sprint Business Internet
AS 1270 UUNet DE
AS 1273 Cable & Wireless Plc.
AS 1290 PSINet UK
AS 1299 TeliaSonera International
AS 1759 Sonera
AS 2683 Radio-MSU
AS 2764 AAPT/Connect.com.au
AS 2828 Verizon Business
AS 2914 NTT Communications
AS 3212 Triera Internet
AS 3216 Golden Telecom
AS 3239 SUrNet – Russia
AS 3257 Tiscali International Network
AS 3292 TDC A/S
AS 3300 BT Infonet
AS 3303 Swisscom
AS 3320 T-Systems DTAG
AS 3327 Data Telecom
AS 3356 Lumen Technologies
AS 3491 Beyond the Network (BtN)
AS 3549 Lumen Technologies
AS 3561 Savvis Communications
AS 4436 GTT Communications, Inc
AS 4589 EasyNet
AS 5400 BT Ignite
AS 5408 Greek Research and Technology Network
AS 5511 Orange
AS 5523 RM Telecom
AS 5580 Atrato IP Networks
AS 5617 Polish Telecom
AS 5650 Electric Lightwave
AS 6128 Altice
AS 6461 Zayo Group
AS 6663 Euroweb Romania
AS 6667 Eunet Finland
AS 6695 DE-CIX
AS 6730 sunrise / TDC Switzerland AG
AS 6854 Telecom Centre Joint Stock Company
AS 6855 SK Slovak Telecom
AS 6993 InterNAP – AS6993 – AS64512
AS 7018 AT&T Communications
AS 7029 Windstream Communications
AS 7132 SBC Internet Services
AS 7385 Integra Telecom Inc.
AS 7474 Optus (Owned by Singtel)
AS 7911 Lumen Technologies
AS 7922 Comcast Cable Backbone
AS 8001 Net Access Corporation
AS 8218 Neo Telecoms Group
AS 8220 COLT Internet
AS 8308 NASK
AS 8319 NETHINKS GmbH
AS 8374 Polkomtel S.A.
AS 8437 TELE2UTA Telekom GesmbH
AS 8708 Romania Data Systems S.A.
AS 8714 LINX Route Server
AS 8897 Mistral Internet Group
AS 8928 Interoute
AS 9002 RETN
AS 9009 RealROUTE International Network
AS 9026 Utility Line Italia S.r.l.
AS 11537 Abilene I2 Backbone
AS 12332 Primorye
AS 12732 Cogent Multihomed ISPs
AS 13105 LUKoil Inform
AS 15412 FLAG Telecom
AS 15725 IKS GmbH
AS 15756 Caravan
AS 16030 Alta Tecnologia en Comunicaciones
AS 19092 360Networks
AS 19401 NRL PacketNet
AS 20473 Vultr
AS 22773 Cox Communications
AS 23265 Pocket iNet
AS 29838 Atlantic Metro
AS 33891 Core-Backbone
AS 45177 Vibe Communications
AS 49544 i3D.net