Two NIC's connected to same subnet: routing question

[Henry Su]

You can configure both NIC as /32. You also need proxy arp installed and
listen on both NIC. Then the traffic should be able to follow between two
NICs. Since Proxy ARP always answers its MAC to clients, so the clients can
always send traffic to em1 or em0. Based on client's mac entry in the ARP
table, client to client traffic is easily transferred. Other traffic should
be able to direct to default gateway.

If you know other options, I am interested to hear.

Thanks.

-----Original Message-----
From: owner-freebsd-net at freebsd.org
[mailto:owner-freebsd-net at freebsd.org]On Behalf Of Xin LI
Sent: Tuesday, February 01, 2005 10:12 AM
To: freebsd-net at freebsd.org
Subject: Two NIC's connected to same subnet: routing question


Dear folks,

I think I got confused with the routing problem we will have when at
least two NIC's are connected into the same subnet.

The scenario:
em0: 192.168.0.1/24
em1: 192.168.0.2/24

We can't simply configure like this, since 192.168.0.0/24 network route
exists as soon as either em0 or em1 is up.  A workaround for this is
that we assign 192.168.0.2/32 for em1, but that has another issue that
all traffics will go through em0 for "outgoing", say, outside the
current network.

A google of the issue has indicated that the "Move ARP out of routing
table" work done last April should have resolved this, as "With this
change it is possible to have more than one interface in the same IP
subnet and layer 2 broadcast domain.".  However, what I have found from
our mailing list archive says only to assign /32 IP address, or remove
routing item from route table, which is essentially identical to the /32
solution.

So is there any way to utilize the both NIC's?  I think I have been
confused :-(

Cheers,
--
Xin LI <delphij delphij net>  http://www.delphij.net/