Subject: Re: [RPSEC] BGP Requirements Draft

From: Sandy Murphy <[email-masked]>
Date: Mon, 26 Sep 2005 10:43:18 -0400 (EDT)

>Even with BGP secured, you still have to trust that ASes you forward
>to/from have described their state to you or others correctly.

Maybe I've misunderstood the importance of loop-freedom.  I thought it
was a central tenet of BGP-dom that BGP was loop-free.  That this was
the reason for including the AS_PATH in the UPDATE from  the beginning.

If making loop-freedom checks is no big deal, why are the checks there
to begin with?

--Sandy

_______________________________________________
RPSEC mailing list
[email-masked]
https://www1.ietf.org/mailman/listinfo/rpsec

---

From: Paul Jakma <[email-masked]>
Date: Mon, 26 Sep 2005 15:59:58 +0100 (IST)

On Mon, 26 Sep 2005, Sandy Murphy wrote:

> If making loop-freedom checks is no big deal, why are the checks 
> there to begin with?

You trust your peer to describe their state correctly.

Having signed in-line AS_PATH does not make that trust any more than 
blind trust. Eg:

A-B---C-n
    \ /
     D

C announces prefix n to both B and D. B announces to A. A gets:

  B<-C

However, the operator of B installs a static route to send traffic 
for prefix n via D. No amount of AS_PATH signing can stop this. Why 
would B such a thing? Who knows (An accident? incompetence? 
Malfeasance? Maybe D is a competitor of A and pays off B).

The point being: all the in-line signing of AS_PATH's can't prevent 
the above, at some level inter-domain routing is a 'faith' based 
venture - regardless of what we do here.

regards,
-- 
Paul Jakma	[email-masked]	[email-masked]	Key ID: 64A2FF6A
Fortune:
Truthful, adj.:
 	Dumb and illiterate.
 		-- Ambrose Bierce, "The Devil's Dictionary"