Re: What's up with BGP communities?

[Gael Hernandez via NANOG <nanog () lists nanog org>]

This page has compiled community guides from
several network operators. Looks like a good resource.

https://onestep.net/communities/

Gaël


On Thu 22 Jan 2026 at 22:08, John Fraizer via NANOG <nanog () lists nanog org>
wrote:

> Read RFC1997 and RFC1998 for more info n depth understanding of communities
> and their value/use.
>
> --
> John Fraizer
> LinkedIn profile: http://www.linkedin.com/in/johnfraizer/
>
>
>
>
> On Thu, Jan 22, 2026 at 5:02 PM William Herrin via NANOG <
> nanog () lists nanog org> wrote:
>
> > On Thu, Jan 22, 2026 at 1:55 PM Ronan Pigott <ronan () rjp ie> wrote:
> > > IIUC, a "route map" is a configuration local to the BGP router. So, an
> > > operator may make some decision about the meaning of a community and
> then
> > > attach it to routes advertised to their peers, but no peer can
> reasonably
> > > act on the community information without understanding the meaning
> > intended
> > > by the owner, right?
> >
> > Correct.
> >
> > > So if I operated a network and my BGP peer advertises
> > > routes that belong to a bunch of communities, how can I possibly learn
> > the
> > > intended meaning of those communities to configure a sensible route map
> > for
> > > my router?
> >
> > You ask your peer. In some cases, the peer writes a web page which
> > explains what their communities mean so that they can just say, "look
> > at this web page." And then you have sites like bgp.tools which
> > collect the information from the various web pages individual networks
> > have published into a large database.
> >
> > Because the communities have arbitrary meanings, those meanings are
> > communicated person to person, not machine to machine.
> >
> > Regards,
> > Bill Herrin
> >
> >
> > --
> > For hire. https://bill.herrin.us/resume/
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