problems with nics and multiple ips

[Arnau <arnaulist@andromeiberica.com>]

Hi all,

  Yesterday I had a problem with a server and adding/removing ips to a nic.

  I have two servers and I had to switch their ips remotely. To do that 
then I decided to add two extra ips to each server, then stop the 
"interface" with ip that I had to switch and then leave just one ip in 
each server. What I did is the following:

  1.- Edit the /etc/network/interfaces of each server and add the 
second ip:

# The loopback interface
# automatically added when upgrading
auto lo eth0
iface lo inet loopback

iface eth0 inet static
        address 192.168.10.3
        netmask 255.255.255.0
        gateway 192.168.10.1

#added part
auto eth0:0
iface eth0:0 inet static
        address 192.168.10.4
        netmask 255.255.255.0
        gateway 192.168.10.1



  2.- then I did ifup eth0:0 and everything goes ok, The problem is 
when I want to stop the primary ip. I wasn't able to do it. With "ifdown 
eth0" I stopped the whole interface and I had to call somebody to go 
there an do an ifup eth0.

  I tried to modify again the interfaces file and try with 
/etc/init.d/network restart, even modify the file and:
ifdown eth0; /etc/init.d/network restart; ifup eth0. Nothing worked, 
finally what I did was modify the interfaces and restart the server. I 
think there should be a better way to do this, do you know how?

Cheers!
--
Arnau