Subject: Uncommon routing arrangement
To: None <>
From: John Klos <>
List: tech-net
Date: 02/16/2005 10:30:40

I will soon have at my office two bridged ADSL connections from Speakeasy 
(Covad is completely no help when there are problems), and I'd like to set 
up basic failover.

My first question is this: how do the bridged ADSL connections work? Is 
there any real reason why many providers don't give more than 8 addresses 
over a bridge? I asked for a subnet to be routed to one of my machines, 
but they don't do that. But I am wondering if, since both ADSL bridges are 
on the same Speakeasy class C network, if either can be used for the 
other's IPs, or if there's some strange way that they handle MAC addresses 
or something. (They're not installed yet, else I'd do the simple thing 
and test them)

The next question is the one that I'm most curious about - I've had 
machines on two connections at a time, and switching the default route was 
simple. However, now I'll have a machine on two connections, both on the 
same subnet, and both with the same default route. How do I tell the 
system to use one ethernet interface / IP address for communicating with 
the default route as opposed to the other?

Finally, and somewhat separately, does anyone have any recommendations for 
sharing bandwidth between the two lines and traffic shaping on both? When 
I'm doing NAT through the primary machine which will be physically 
connected to both lines, I think it'd be pretty simple, but unless I 
create my own bridge between the lines and my other machines which are 
supposed to get the public IPs, I can see that this might be difficult... 
Any suggestions are welcome.

John Klos
Prayer has no place in the public schools, just like facts 
have no place in organized religion.
   - Superintendent Chalmers