Re: What's up with BGP communities?

[Josef Miegl via NANOG <nanog () lists nanog org>]

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" <nanog () lists nanog org> 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
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