North American Network Operators Group

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Re: BGP with AT&T owned space

  • From: Christian Nielsen
  • Date: Thu Aug 09 15:16:32 2001


Are you a peer or customer of ATT? or are you seeing these from your

If it is the first case, you can ask ATT to not leak more specific routes
to you. Also, they have a community you can use to block them.

If it is the second, please talk to your upstream. That means they are
leaking ATT more specifics. I know of one provider that has done this more
than once in the past... Contact them and make sure they have the correct
route-maps/filters in place.

And if you really dont like seeing them...

prefix-list idontlikethis le 8

that should solve your problem.

On Thu, 9 Aug 2001, Jeff Harper wrote:

> Just curious if anyone has noticed the leaking of the more specific routes
> of AT&T's IP space in their BGP table.  Here's what we're seeing in ours:
> #s ip ro
> Routing entry for, 589 known subnets
>   Variably subnetted with 9 masks
> B [20/0] via x.x.x.x
> B [20/0] via x.x.x.x
> B [20/0] via x.x.x.x, etc.....
> I should just see the aggregation of the /8, but something changed on
> 8/7/2001 at precisely 8 AM Eastern time.  The same is with their 24/8 and
> their other networks as well.  I have about 40,000 superfluous networks in
> my BGP table.  ;)
> Jeff