Advice on BGP traffic engineering for classified traffic

Kevin Loch kloch at
Wed Oct 26 22:19:37 UTC 2011

Jack Bates wrote:
> I'm curious if anyone has a pointer on traffic manipulation for 
> classified traffic.
> Basics, I have a really cheap transit connection that some customers are 
> paying reduced rates to only use that connection (and not my other 
> transits). Though I've considered support for cases where NSP peering 
> disputes break out. While I can advertise their networks out the correct 
> transit for return traffic, I still have to figure out how to handle 
> egress traffic.
> I'm guessing the crux of it is policy routing based on source address, 
> but I'm interested in ways to engineer it to easy management and 
> scalability. I've considered the possibility of an l3vpn to interconnect 
> customers that are not requiring full routes, and possibly some type of 
> vpls tunnel terminated at the necessary router for customers who need 
> full routes.
> Thoughts, pointers, suggestions?

One simple way to do this is with two routers each with a different
table.  One for your expensive transit and one for your cheap transit.
Each customer's vlan is on both routers with vrrp preference
set to the desired router for non-bgp customers.  expensive transit
customers have the ability to failover to the cheap router.
you may or not want to allow the reverse to occur.

- Kevin

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