Kirby Files kfiles at
Sun Nov 2 07:20:26 UTC 1997

> Does anyone know if ANS, digex, mci etc.
> provide communities that encompass their internal/customer routes?

Can you be a little more precise?  Most providers probably use
communities to tag subsets of the routes they carry, and some set of
those communities, either through inclusion or exclusion, almost
certainly describes the set of customer routes carried by that
provider.  (I'm sure this can be stated more clearly.)  GTE certainly
does, I'm pretty sure MCI still does, etc.

Now, will we "provide" these communities?  Do you mean send-community
to a customer?  To a peer?  Many of a provider's internal communities
would be at best irrelevant and at worst potentially harmful in the
context of another AS's policy.  With no good way to delete
such communities while preserving communities that describe their
customer base (and ixnay on "match community... set community") why
would a provider want to send all community tags to either a customer
or a peer?

Another question is, "Why do you want this info?"  Taking full transit
routes from a provider and trying to set localpref or MED based on
whether the destination is a customer or peer network?  If you are
taking transit, there are good arguments for *not* running

> If certain ones don't, is there any reason that they
> have against such a community?

See above.  Some/most providers can probably be convinced to send
community-tagged routes to customers (hey, the customer's not *always*
wrong, and it depends on how much proprietary configuration info a
provider is worried about conveying -- of course, I find this last
amounts to mostly hogwash).  Nobody's going to send them to peer

Kirby Files
Network Engineer 
GTE Internetworking
kfiles at

More information about the NANOG mailing list