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Re: weird BGP cisco-ism? [problem resolved]
From: Danny McPherson <danny () genuity net>
Date: Fri, 11 Jul 1997 17:42:15 -0700


      You can build your customer BGP filters off data in the IRR.  Make
it a requirement that BGP customers must keep that information up to date
(or do it for them).

OK.  So I apply an ingress filter (ideally built from the IRRs) to a customer 
peer.  Then I have to add the cusomter's AS(s) prefixes to every eBGP peer's 
egress ACL (including customer peers) so that the networks will be permitted.

The customer begins advertising a newly allocated netblock.  Now virtually 
*every* BGP peers ACL has to be modified & deployed and the source AS will 
need to either flap the route or reset the session.

If I had tagged the customer's prefixes with a BGP community when I picked up 
the routes ..and have filters in place that deny/permit predefined communities 
to all eBGP peers, all I would need to be concerned with is the customer's 
ingress ACL.

IMO, ACLs alone won't scale. 


-danny



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