two interfaces one subnet

Date: Mon, 11 May 2009 18:29:08 -0500
From: Chris Adams <>

Once upon a time, Kevin Oberman <> said:
> > From: Chris Meidinger <>
> > For example, eth0 is and eth1 is, nothing like
> > bonding going on. The customers usually have the idea of running one
> > interface for administration and another for production (which is a
> > _good_ idea) but they want to do it in the same subnet (not such a
> > good idea...)
> This will not work right. One interface can be, but any
> added interfaces would need to be /32 (

I don't know which OS(es) you are using, but that's not true in Linux.
I see this all the time at home; if I plug my notebook into the wired
LAN and still have the wireless enabled, both will get an IP (in the
same subnet) from DHCP. The wired link is the preferred default route
by default, but you can easily set up routes for some networks via the
wireless link.

You can also set up multipath routing to send packets out both links. I
think you can also use IP policy routing to control the choice of
outbound interface by rule (e.g. based on source address).

This is true if you are using the WPA supplicant. It does a bit of
magic. (You can do the magic by hand without the supplicant, but it is a
pain or was the last time I tried.)