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North American Network Operators Group Date Prev | Date Next | Date Index | Thread Index | Author Index | Historical RE: Policy Routing
On Sun, 26 Aug 2001, Przemyslaw Karwasiecki wrote: > Unless I am misunderstand how BGP (and routing at all) > works something very seriously wrong with your suggestion. Yeah...I should have put a few more seconds thought into that reply :) > Your border router will advertise to a customer only best > and active routes. You cannot advertise to BGP peer two routes > to the same destination. So modifying AS_PATH will not work, > because you will send to Customer X only best selected route > from your border router. This would basically tell the customer "don't send us traffic" since assuming the cheapest path isn't the best path, the majority of routes you send the customer would be non-cheapest peer paths with lots of prepending. Just doing simple policy routing based on the customer's source address to a next-hop of the cheap peer could cause all sorts of problems as well. What if the cheap peer doesn't even have routes to the destination? i.e. the C&W/PSI peering issue a few months ago. Say C&W is your cheap peer and you send customer-X traffic to C&W desined for PSI. C&W can't deliver it and just drops it. Sucks to be customer-X. It looks like this problem is much easier to solve for incoming traffic than for outgoing. -- ---------------------------------------------------------------------- Jon Lewis *[email protected]*| I route System Administrator | therefore you are Atlantic Net | _________ http://www.lewis.org/~jlewis/pgp for PGP public key_________
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