run auto script when interface comes up or down on centos

bobo0110 · 03-15-2011, 12:38 AM

Hi all !!!

i have a centos box with interfaces eth0 and lo:0.
i want to write a script to stop or start lo:0 automatically when eth0 comes down or up.
is there any way to do that?

thanks,

chrism01 · 03-15-2011, 02:27 AM

As a rule, lo:0 (ie localhost) is always up. Is there any reason you'd want it down? It's the i/f that the system uses to talk to itself.

bobo0110 · 03-15-2011, 03:15 AM

Actually, I have a load balancing model using 2 LVS servers for failover (see attached figure)
Each LVS has one real i/f eth0 & one virtual i/f lo:0 assigned virtual ip
Sometimes eth0 in one of 2 LVS servers down, the incoming requests don't come the other server automatically.
The main reason is the router keeps holding MAC of server (has eth0 down) not the one of other server if i/f lo:0 is up (i really don't know why)

So needing a auto script in this case is very helpful

thanks,