Howto for BGP black holing/null routing

Wed Feb 23 15:36:51 UTC 2011

On Tue, Feb 22, 2011 at 4:55 PM, Jack Carrozzo <jack at crepinc.com> wrote:
> Maybe I read your question wrong, but null-routing things at your border is
> often not very useful if the traffic is flooding your transit links. Most
> transits publish their community lists - you just need to tag the prefix you
> want to blackhole with the right community.

This is certainly true.  Although most "big transit networks" offer
this feature today, there are some important differences in what some
of them will and won't accept.  Some will only learn /32s, some say
they'll accept /30-/32 but nothing shorter, some will honor anything
you send them.  This may be undocumented.

Some networks seem to have forgotten about this feature when
implementing IPv6, even though it is offered for IPv4.

I don't see any value in not accepting a RTBH /24 but accepting a /30.
 I also don't know of any platform issues which would make deploying
RTBH for IPv6 BGP customers any more difficult than doing so for IPv4.

-- 
Jeff S Wheeler <jsw at inconcepts.biz>
Sr Network Operator  /  Innovative Network Concepts