How to correctly use 2 on board nics

[John Nielsen]

Quoting Ivan Carey <ivan at careytech.com.au>:
> I have a server board with 2 onboard nic's
> I have set them up in rc.conf as follows
>
> defaultrouter="192.168.1.1"
> network_interfaces="em0 em1 lo0"
> ifconfig_em0="inet 192.168.1.3 netmask 255.255.255.0"
> ifconfig_em1="inet 192.168.1.4 netmask 255.255.255.0"
>
> The question, is this the correct configuration?

Manually specifying network_interfaces is deprecated (take that line 
out). Putting both NIC's on the same subnet and segment but with 
different IP's like this may not be too useful..

> If I have both nic's connected to the switch I can ping 192.168.1.1 
> and 192.168.1.3 and 192.168.1.4
>
> If I have only em0 connected I can ping 192.168.1.1 and 192.168.1.3
>
> If I have only em1 connected I can ping 192.168.1.3.

That is because the route to 192.168.1.1 is associated with em0 at this point.

> What could the 2 onboard nic's be best used for. I was thinking that 
> in the event on was to fail then the other would still be ok.

For that to be most useful you'll want to set something up so they can 
share the same IP. The lagg(4) (link aggregation) virtual interface has 
already been mentioned, but I believe it is still only available in 
-CURRENT. Other possibilities might include attaching ifconfig scripts 
to link up/down events or [lack of] ping responses on one or both 
interfaces.

JN