[TriLUG] Conflicting Default Gateways

[Brian Henning]

Hi List,
  Ok, I think I have a foggy idea of why this is the case, but I would
greatly appreciate some tips on how to get around it:

I've got a server with two NICs which are on different subnets (for
argument's sake, we'll say eth0 is on 192.168.50.0/24 and eth1 is on
192.168.100.0/24).  Both subnets have their own internet gateways; .50 has
1.5Mbit DSL service, and .100 has some sort of cable-based service.  Right
now, eth0 is configured to its subnet's default gateway (.50.1), and eth1 is
configured with no default gateway.  In this configuration, things work
normally.  However, if I configure eth1 to be aware of its default gateway
(.100.1), something becomes amiss, and things such as host and dig get
broken.  I'm using system-config-network to make these settings; I don't
know if that matters.

Ordinarily, I simply wouldn't care.  The server does all its dirty work via
eth0 anyhow.  The problem is, I would like to have it download large files
(such as the FC3 ISOs) using eth1, so that the DSL bandwidth isn't hogged.
I don't care about maxing out the cable bandwidth, because no one uses it
(it's only there as a failsafe in case the DSL goes down); but everyone uses
the DSL so I'd have to do something like only download overnight, or
rate-limit, neither of which is a solution I am patient enough to persue.

So, is there a way to achieve this?  It seems like I should just be able to
configure each interface's default gateway and tell the ftp client to bind
to eth1, but as I've explained, attempting to have both interfaces' default
gateways configured seems to result in some kind of conflict.

Thanks for all the help!

Cheers,
~Brian

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Brian A. Henning
Strutmasters.com
866.597.2397
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