routing table madness

[Lonni J Friedman]

On Mon, Nov 5, 2012 at 6:31 PM, David A. Bandel <david.bandel at gmail.com> wrote:
> On Mon, Nov 5, 2012 at 9:08 PM, Lonni J Friedman <netllama at gmail.com> wrote:
> [snip snip snip]
>>>
>>> I could use a little more detail, but this is easily fixable.  Tell me
>>> what needs to route where and I'll send you a list of commands.
>>
>> Thanks!  The *only* thing that should ever be routed over em1 is
>> traffic for 10.0.0.101.  Everything else should go out over em3.  Let
>> me know if you need any other specifics, and I'll provide them.
>
> Then make the netmask for em1 be 255.255.255.0 (/24) or even smaller
> (you could make this interface a /29 -- 255.255.255.248, but not a /30
> because .100 is the network address for that network, so the hosts
> would have to be .101 and .102 w/ .103 the broadcast).
>
> It is also possible to not use a bridge but to create a policy routing
> table for those things destined for the one host on em4
> in /etc/iproute/rt_table you would need a named entry, say foo with a
> number (see example), then:
> ip ru add to 10.31.96.100 table foo
>
> but your best bet is still a bridge over em3 and em4, especially if
> either one interface comes up and goes down or an IP will be connected
> to one or another (but not active on both simultaneously) interface.

Thanks!  Changing the netmask to 255.255.255.248 on em1 fixed it.