Where are static bogon filters appropriate? was: Bogons

Mikael Abrahamsson swmike at swm.pp.se
Tue Mar 6 17:02:06 UTC 2007

On Sun, 4 Mar 2007, Sean Donelan wrote:

> When customers misconfigure their router, e.g. wrong BGP neighbor or 
> ASN, wrong interface IP address, exceed max prefix limit, etc; don't 
> they lose Internet connectivity until they fix it?
> A properly configure router should never forward even a single bad 
> packet. If it does, isn't it likely to have configuration problems so 
> why continue to keep misconfigured routers connected?
> Customers are unlikely to fix problems which don't cause them to lose 
> service.

Even though the BOFH in me agrees with you, I also know that every cent on 
my paycheck comes from the customers, so I prefer not to treat them like 
crap. If I can protect the internet from my customers by doing uRPF or 
source IP based filtering, I achieve the same thing as you but with less 
customer impact.

Also, all the examples you give implies a BGP transit customer. I am 
imagining all kinds of customers, from colo customers where I am their 
default gateway, to residential customers where it's the same way. 
Disabling their port and punting them to customer support is NOT a cost 
efficient way of dealing with the problems, at least not in the market I 
am in.

Mikael Abrahamsson    email: swmike at swm.pp.se

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