[SATLUG] **SOLVED** Routing from one box to two different ISPs

[Bruce Dubbs]

David Salisbury wrote:
> Well, now I've got it working!!  Using the guide at the link that I had mentioned before:
> 
> http://tldp.org:80/HOWTO/Adv-Routing-HOWTO/lartc.rpdb.multiple-links.html
> 
> I now have a new routing table:
> 
> Destination     Gateway         Genmask       Flags Metric Ref Use Iface
> <DSL Netmask>   *             255.255.255.255 UH    0      0     0 eth0
> <RR Netmask>    *             255.255.255.255 UH    0      0     0 eth1
> <RR Broadcast>  *             <RR Netmask>    U     0      0     0 eth1
> <DSL Broadcast> *             <DSL Netmask>   U     0      0     0 eth0
> 127.0.0.0       *             255.0.0.0       U     0      0     0 lo
> default         <DSL Gateway> 0.0.0.0         UG    0      0     0 eth0
> 
> And that routing table, coupled with the ruleset of 2 rules mentioned 
in the link above, has now created the correct traffic flow to the box!
All of its functions seems to work from both interfaces now (web, etc).
Cool!!  Thanks for everyone's help and input!  Now I will look into the
multipathing that you brought up, Daniel, because I am also interested
in fallback connections and the like.

Are the first two entries necessary?  Since the mask is /32, the only
thing they are being routed to is whatever entry you have for <DSL
Netmask> explicitly.  For example, my DSL segment gives:

64.123.68.0     *       255.255.252.0   U     0      0        0 eth0

If I used a netmask of /32 instead of /22, it would only match
64.123.68.0 and that is not a host so it would never be used.

Also, I don't think you are using RR for any outgoing packets except
those addresses that match  <RR Broadcast>/<RR Netmask>.  I don't think
that's what you intended.  Unless I'm mistaken, you really need two
gateways to do what you want.

Also, I think your definitions of Netmask and Broadcast in column one
are not the standard for netmask and broadcast.  For example, the
netmask for my DSL above is 255.255.252.0 and the broadcast is
64.123.71.255.  Neither makes any sense for a Destination.

  -- Bruce