ALTQ & Multiple Connections

[Max Laier]

On Wednesday 03 September 2008 04:08:43 Lance Murdock wrote:
> I have two Internet connections on my firewall, and a busy web server.
> They are both "burstable" connections, where the commit rate is much
> lower than the maximum connection speed.  I pay a flat rate
> up to the commit rate, but If I go over, I get charged per mbit.
>
> One of the connections' overage rate is a lot cheaper than the other.
> So, what I would like to do is fill up the first connection right up to
> its commit rate and then dump all remaining traffic to the second
> connection, thus guaranteeing myself the cheapest bill at the end of
> the month.
>
> With ALTQ, I can see how to limit outgoing bandwidth by dropping packets,
> but I don't want to drop the packets, I want to force them out the
> other interface, as I might with pf's route-to.
>
> Is this possible with pf and ALTQ?

No and I don't know of any software that would make that possible - probably 
because it's a horrible idea.  You will run into all kinds of trouble with out 
of order packets.  Let alone the issues you will have if any of your ISPs does 
source filtering, or with asymmetric return paths and possibly NAT.  There 
really is no way to do what you have in mind.  The only thing you can do is 
some level of *per-flow* round-robin (with weights) onto your outgoing 
connections - maybe adjusting the weights according to ALTQ usage stats.  But 
that's a very rough estimate - but you can't do better than that, anyways.

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