North American Network Operators Group

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Re: Bogon list

  • From: David McGaugh
  • Date: Tue Jun 04 14:07:11 2002

I agree with Joe on this. At one time we were filtering 198.32/16 from
our peers but ran into things like ( breaking. We now
only filter on IXP blocks for which we participate.

While on the subject of IXP blocks, we also ended up redistributing the
IXP blocks and sending them to our BGP customers (who do not receive a
default) so that traceroutes and such from Looking Glasses do not break.
They can then choose to filter them as they wish.


Joe Abley wrote:
> On Tuesday, June 4, 2002, at 12:48 , Barry Raveendran Greene wrote:
> >> Then we come to the extra bogons like exchange point allocations. Can't
> >> forget them. :)
> >
> > I've never heard anyone refer to the IXP allocations as "bogons." Plus,
> > I've
> > not heard of anyone filtering the IXP prefixes on their ingress peering
> > filters. Egress peering filters - yes.
> Depending on your internal routing policy, it may well be important not
> to learn routes to exchange points to which you connect.
> A straightforward example is when people accidentally propagate the
> prefixes and Interfaces on the LINX
> exchange fabric are currently numbered within, so if my
> LINX router learns the longer prefix routes from somewhere else, my EBGP
> sessions across the exchange get hijacked. Without the prefix length
> aspect the effect is less obviously serious, but it can still cause
> issues.
> Subnets numbering interfaces on exchange point subnets, for exchange
> points at which I participate, can hence generally be considered
> bogonish by me. For exchange points at which I do not participate this
> need not be the case. The list of EP-derived bogons is, following this
> logic, operator-specific.
> Joe