At the company I work for, we have two internet connections at each of our two branches. Each branch has a standard 1.544 Mbit T1 line and a 384/384 business class SDSL line.

I am planning to replace our current hardware routers with Linux machines. We are currently using Xincom XC-DPG603 Twin WAN series routers. They have a nifty feature that allows you to balance traffic on the two WAN interfaces. However, you can specify what amount of traffic goes through each. For instance, you can have 70%/30% by bytes [which is what we're using right now]. You can also do it per connections and so forth.

Basically, I am wondering if there is a way to do this using Linux traffic scheduling. I have been able to use the TEQL qdisc to do 50/50 balancing between two [VPN] interfaces on a local net, but I am much more interested in doing a non-symmetrical load balance. I have scoured the net and googled everything I could think of to no avail.

Note: if it's just possible to do it with point-to-point type links, such as a VPN, then that is fine. Our primary use of this system is redundancy for the inter-office VPN connections.

I hate to suggest a non-penguin solution, but being open source I guess it's ok. Using "PF" on OpenBSD is one of the most reliable things on earth, and amazingly configureable. Google it.

Have fun.

I am quite familiar with PF, though I never thought of it. Thank you for the suggestion.

As I'm sure this will probably come up again, I seem to have found a solution that works at least in theory. Assuming the kernel has multipath support [under advanced routing services], iproute supports weighted routes:

ip route add 10.0.1.0/16 nexthop via 10.254.0.2 weight 7 nexthop via 10.254.0.2 weight 3

This causes the kernel to choose the routes in a proportion of 7 to 3 when it does routing lookups. I have not been able to get it work as I'd hoped, however I have done only very preliminary testing. In the long run, however, when it has to re-look up the table, it should probably have an effect.

Cisco's EIGRP does unequal multipath routing, but it is [as far as I know] patented. In any case, there is no working implementation in the OSS world [i.e., as a part of Zebra or Quagga]. Cisco's specs don't go into any detail that would be useful for implementing it, either.

Have a look at the Linux Advanced Routing and Traffic Control Howto:
http://lartc.org/howto/