Looking through all the advanced routing docs I can find, I think I have dug up enough parts to cobble something together to do what I need but I am befuddled. Here is a description of my problem: Two providers. A primary I will call provider-A and a backup that I will call provider-B. I collect full routes from both by BGP. My aggregate traffic output varies from about 130MB in the middle of the night up to about 300MB during the day ... a little lower on the weekends. Provider-B is more expensive and has a 50MB minimum. I have fiddled with my BGP so that I end up sending about 45-50MB of traffic to provider-B during my peak time of the day. What I would like to do is pretty much nail provider-B to 50MB at all times using a Linux box in the traffic path. A bit more detail on what I am trying to do: A packet arriving from inside my network has 4 possible dispositions. 1. There is a route to the destination from both providers (most likely). 2. There is a route only from Provider-A. 3. There is a route only from Provider-B. 4. There is no route from either provider. I can make zebra put routes into realms. I can then check arriving packets to see if a realm has a route to the destination. Packets in disposition 2 must go to provider-A, packets in disposition 3 must go to provider-B. Packets in disposition 1 are what I call "the pool" and may go to either A or B to get to their distination. What I want to do is create three streams ... A, B, and Pool. I need to mark A so that it gets routed to provider-A (with FWMARK or some other means ... say TOS), mark stream B so that it is nailed to provider B, BUT when stream B is below 50MB, I want to pull in packets from the pool to bring it up to 50. I do NOT want to rate-limit at 50 because if I loose my link to provider-A or they have a peering issue, more than 50MB might need to go to B, I just want to stop pulling traffic from the pool at that point. Any traffic in the pool remaining after B has pulled what it wants would be marked for provider-A. What I end up with is something like this: Traffic that can only be routed to A goes to A Traffic that can only be routed to B goes to B If B is less than 50MB, get some of the traffic that could go to either A or B to make up the difference Remaining traffic goes to A. Is anyone here ever done this?
