Subject: Re: Two interfaces on same network
To: Arto Huusko <arto.huusko@utu.fi>
From: Manuel Bouyer <bouyer@antioche.lip6.fr>
List: netbsd-help
Date: 09/21/2001 08:56:22
On Fri, Sep 21, 2001 at 12:40:08AM +0300, Arto Huusko wrote:
> Um, I seem to remember that the situation didn't change much.
> The interface that was 'up', if it was configured first, could be used
> as normal. I did not try did bridging work at that time.

Hum, it would have more chances of working with bridging enabled :)

> 
> Thank you for your reply, but this is a dead issue now. I realised that
> the box should've done too many things that bridging really was not an
> option. Because the machine really needed IPs on both interfaces. Happily,
> NAT was an alternative (I tried bridging because I first had understood
> NAT was not possible) and everything works now great.
> 
> 
> But still, bridging aside, I am curious: can two interfaces on a computer
> be in the same network? I pretty much came to the conclusion that no
> but I still have a nagging feeling I'm wrong. How would the system
> be configured in that case to work properly?

No, it's not possible to have 2 interfaces on the same network, or at last it
won't work out of the box. It may be possible to get it working by manually
changing the routing table. Each machine of the network has an entry in the
routing table with it's ether address:
Internet:
10/24              link#9             UC         36        0      -  vlan1
10.0.0.1           00:00:c0:f1:ee:e9  UHLc        0        3      -  lo0
10.0.0.5           00:c0:4f:b9:f4:33  UHLc        0        0      -  vlan1
10.0.0.25          link#9             UHLc        0        2      -  vlan1
10.0.0.231         00:04:4d:3d:f7:80  UHLc        0        0      -  vlan1

By default they willbe added to the interface which has the route entry to the
network (10/24 here), you have to change it manually to point to the
other interface. I'm not sure if it's possible with the route
command, it may require some more hacking.

--
Manuel Bouyer, LIP6, Universite Paris VI.           Manuel.Bouyer@lip6.fr
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