Blackhole Routes

Pete Templin petelists at templin.org
Thu Sep 30 19:42:15 UTC 2004


Deepak Jain wrote:

> If providers start tying their customer's blackhole announcements to the 
> provider's upstreams' blackhole announcements in an AUTOMATIC process, 
> bad things <tm> are likely to happen. What happens when a customer of a 
> provider mistakenly advertises more routes than he should [lets say 
> specifics in case #1] you can flood your upstreams' routers with 
> specifics and potentially cause flapping or memory overflows...
> 
> In case #2, presumably the blackhole community takes precedence, so if a 
> customer is mistakenly readvertising their multihome provider's table 
> with a 666 tag, all of the upstream providers might be blackholing the 
> majority of their non-customer routes.

I build two prefix lists for each customer.  One represents the exact 
match routes that I'm willing to propagate, and the other covers "le 32" 
more specifics of what I'm willing to allow special treatment on.  They 
can't blackhole anything outside what they would otherwise be allowed to 
announce (and I use it for several other special cases as well). 
Customers who are single-homed and otherwise static routed are welcome 
to use BGP for these special cases; their prefix lists reflect the fact 
that their space is not to be propagated.

pt



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