[c-nsp] BGP prefix announcement question..

[Mark Tinka]

On Wednesday 25 June 2008 11:13:55 pm Pete Templin wrote:

> Every BGP prefix in our network gets tagged with at least
> one community, that of a "magic code", upon
> origination/learning/injection/whatevah. It's basically
> of the form <ourAS>:ABCDE, where A indicates the type of
> route (customer, ours, public peer, private peer, paid
> transit) and BC indicates the POP of first contact.  We
> then filter based on the :A code before propagating to
> upstream providers.

We do the same.

Each route is marked with a community as it enters the 
network from an external source.

> Tedious to author, but phenomenally useful once in place.

Agree, and all worth the effort. We wouldn't have it any 
other way.

As far as blackholing goes, we have a blackhole router that 
originates a route marked with a community corresponding to 
which routers will drop traffic destined to it, e.g., edge, 
peering, transit, e.t.c.

Of course, having a route pointing to the Null0 
(IOS)/Discard (JunOS) interface on all routers at the 
edge/border is a good idea. We use 192.0.2.1, as I'm sure 
do most folk.

Mark.
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