Re: [K12OSN] Virutual Network card etc

["Christopher K. Johnson" <ckjohnson gwi net>]

Heath Henderson wrote:

> OK, I have a server which currently has an IP address of x.x.x.9 and another server which has an address of x.x.x.12 (same subnet for both servers.  
>
> I just got a new one (a beast).  I can run everything from both servers onto this one.  But, I want to know how to setup the two nics to work on the same subnet.
>
> I have two physical nics in this big guy and I want to use them both.
>
> Can I trunk them?  Can I set them up so that one nic has an address of x.x.x.9 and the other x.x.x.12 (this way my other servers will not see a change?)
>
> Box in question is a RH9 box.  Can I set up some type of virtual interface on one of the cards.
>
> Currently, I can add both nics and set IP numbers, but they go silent as soon as I do this.  I am guessing it doesn't know which the default route is etc?
>
> Thanks
>
>
> Heath Henderson
> Assistant Technology Administrator
> McLean County Unit 5 Schools
> Normal, IL 61761   
>  
In lieu of the earlier suggestions I recommend you configure interfaces 
under network-scripts, rather than entering commands after booting or 
adding commands to some start script. As far as I know there is no 
performance advantage to the earlier suggestions.

ifcfg-eth0 contains something like this, given a netmask of m.m.m.m and 
a default gateway address of x.x.x.y
DEVICE=eth0
IPADDR=x.x.x.9
NETMASK=m.m.m.m
BOOTPROTO=none
ONBOOT=yes
USERCTL=no
NO_ALIASROUTING=yes
GATEWAY=x.x.x.y

ifcfg-eth0:0 contains something like this
DEVICE=eth0:0
# Only the differences from base interface need be configured for alias
IPADDR=x.x.x.12

Note that eth0:0 will always be started and stopped with eth0.

You don't want each interface to add another route through its device to 
the default gateway, and that can be controlled several ways.  Note the 
use of NO_ALIASROUTING=yes to prevent a route to the default gateway 
being added via eth0:0 as well as eth0.  Also note that your iptables if 
configured should be revised with rules appropriate to eth0 and eth0:0, 
which may be different, or eth0+ may be used in iptables rules to apply 
to both.

--
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  "Spend less!  Do more!  Go Open Source..." -- Dirigo.net
  Chris Johnson, RHCE #807000448202021