Hi Ronan, you are right, BGP doesn't communicate any communities descriptions.
In the case of bgp.tools, when you create an account and "claim" your AS, you can add these BGP community descriptions for your AS. They also seem to be sources from NLNOG Ring project (https://github.com/NLNOG/lg.ring.nlnog.net/tree/main/communities). January 22, 2026 9:38 PM, "Ronan Pigott via NANOG" <[email protected]> wrote: > Hi, > > First off, apologies if I'm completely lost. I'm not a network professional > of any kind, just a > random with a question I can't find the answer to on the internet. > > Basically, I was poking around on this website called bgp.tools and many ASN > have a page describing > BGP communities known by the network, e.g. > https://bgp.tools/communities/13335. > > It includes descriptions for each one: > >> 13335:10106 PoP: bos01 >> 13335:10358 PoP: cwb03 >> 13335:10712 PoP: den04 >> 13335:10766 PoP: maa05 >> 13335:10920 PoP: zrh02 >> [...] > > I want to know, where does this supplementary information about the > communities come from, in this > case the "PoP: blah" bits? I don't think it is communicated by BGP directly, > so is there some > standard out of band mechanism to describe the communities? Or am I just > ignorant of this BGP > feature? > > The background is that I live in AZ, USA, and am I subscribed to Cox for my > internet service. I > noticed that my ping to "example.com" (literally) is slower on IPv6 compared > to IPv4: > > $ ping -4 example.com > PING example.com (104.18.27.120) 56(84) bytes of data. > 64 bytes from 104.18.27.120: icmp_seq=1 ttl=251 time=9.58 ms > 64 bytes from 104.18.27.120: icmp_seq=2 ttl=251 time=5.94 ms > 64 bytes from 104.18.27.120: icmp_seq=3 ttl=251 time=7.76 ms > 64 bytes from 104.18.27.120: icmp_seq=4 ttl=251 time=6.85 ms > [...] > $ ping -6 example.com > PING example.com (2606:4700::6812:1b78) 56 data bytes > 64 bytes from 2606:4700::6812:1b78: icmp_seq=1 ttl=57 time=20.0 ms > 64 bytes from 2606:4700::6812:1b78: icmp_seq=2 ttl=57 time=19.0 ms > 64 bytes from 2606:4700::6812:1b78: icmp_seq=3 ttl=57 time=20.8 ms > 64 bytes from 2606:4700::6812:1b78: icmp_seq=4 ttl=57 time=19.8 ms > [...] > $ traceroute -IAen4 -z1 example.com > traceroute to example.com (104.18.26.120), 30 hops max, 60 byte packets > 1 10.3.0.254 [*] 0.249 ms 0.361 ms 0.362 ms > 2 10.40.160.1 [*] 8.978 ms 8.658 ms 7.745 ms > 3 100.127.73.232 [*] 6.957 ms 8.557 ms 6.881 ms > 4 68.1.0.187 [AS22773] 8.067 ms 10.434 ms * > 5 184.183.131.9 [AS22773] 13.818 ms 37.728 ms 17.832 ms > 6 162.158.140.23 [AS13335] 16.822 ms 8.761 ms 16.768 ms > 7 104.18.26.120 [AS13335] 8.813 ms 7.852 ms 9.451 ms > $ traceroute -IAen6 -z1 example.com > traceroute to example.com (2606:4700::6812:1b78), 30 hops max, 80 byte packets > 1 2600:8800:1780:c000::1 [AS22773] 0.315 ms 0.360 ms 0.362 ms > 2 2600:8800:17ff:ffff::1111 [AS22773] 6.601 ms 24.911 ms 9.655 ms > 3 2001:578:800:6:8100::818 [AS22773] 31.164 ms 8.727 ms 9.075 ms > 4 2001:578:900:4::2 [AS22773] 8.763 ms 7.661 ms 6.873 ms > 5 2001:578:1:0:172:17:249:32 [AS22773] 29.991 ms 35.838 ms 19.517 ms > 6 2001:578:20:a000::7:1 [AS22773] 21.781 ms 20.676 ms * > 7 2400:cb00:12:3:: [AS13335] 20.474 ms 20.099 ms 19.824 ms > 8 2606:4700::6812:1b78 [AS13335] 20.078 ms 19.747 ms 20.788 ms > > It's not really a problem, but still I just want to know... why? I thought it > would be kind of odd > to have example.com hosted only on IPv4 in the Phoenix area so I was trying > to see if I could > determine whether or not that was the case looking at > https://bgp.tools/communities/13335?show-prefixes=13335:10066, but I think > there just simply isn't > enough information available online for me to find out. > > Thanks, > > Ronan > _______________________________________________ > NANOG mailing list > https://lists.nanog.org/archives/list/[email protected]/message/IC3W2ONG6J7WUKN5QDE6JIOMDNHSCKRB _______________________________________________ NANOG mailing list https://lists.nanog.org/archives/list/[email protected]/message/QC3C6GURNLZ35U7UIXT33CHKORYNGWKF/
