Re: Blackhole Routes

["Wayne E. Bouchard" <web () typo org>]

On Thu, Sep 30, 2004 at 02:15:49PM -0400, Deepak Jain wrote:
> > It goes a little further than that these days. Folks are openly
> > allowing customers to advertize routes with something lika a 666
> > community which will then be blackholed within their network. So if
> > you're a service provider with your own blackhole system, you can
> > easily tie it into your upstream's system and dump the traffic many
> > hops away from you meaning that the traffic is getting dumped closer
> > to the source than the destination in a fair number of cases.
>
> This is very dangerous however.....
>
> 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...

Yes, well, in my case, I go through a dedicated server with multi-hop
sessions and set a prefix limit of 25 or so so I don't get bombarded
with 5 billion /32 routes and don't send those routes upstream. (I try
to play nice when possible.) I expect that the upstreams have various
defense mechanisms of their own to protect them against me
misconfiguring my boxes as well. (It only makes sense..)

> 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.

If the customer does themselves in, thats not something I can really
protect against.

> Non-automatic tying of customer blackholes to upstream or peer 
> blackholes is a powerful tool to improve the stability of the net as a 
> whole.

Yes, but far too slow when you're getting DOSd off the face of several
planets.

---
Wayne Bouchard
web () typo org
Network Dude
http://www.typo.org/~web/