[CentOS] Dual nw card problem again

Mon Jun 28 19:03:50 UTC 2010
Scott Silva <ssilva at sgvwater.com>

on 6-27-2010 2:20 PM Jussi Hirvi spake the following:
> I have had problems like this before. Probably there is something 
> important that I don't know about routing.
> 
> Let me introduce to you "Lasso2", a CentOS 4 www server that has been 
> working perfectly well for years.
> 
> Now I added a second nw card (eth1), automatically using kudzu. I cannot 
> get this dual nw setup to work. The first nw card (eth0) stopped at once 
> working properly, when I added the second card. Hw failure is probably 
> outruled - the connection via eth0 works normally again if I remove the 
> eth1 card and its settings (on reboot with kudzu).
> 
> There are several symptoms with the dual nw card setup, and I cannot 
> really get to diagnosis.
> 
> 1) if you ping lasso2 (the problem machine) with the eth0 ip, the ping 
> requests come in ok, but the ping responses leave the machine via eth2 - 
eth2 or eth1?
> not good. I don't really know how to analyze routing and how to use ip 
> (the program) to fix it, so please tell me about it.
> 
> The "ip route show" output looks perfectly normal to me, it is similar 
> to another 2-card machine I have running (though that is Centos v5)
> 
> [root at lasso2 ~]# ip route show
> 62.236.221.64/28 dev eth1  proto kernel  scope link  src 62.236.221.75
> 62.220.237.96/27 dev eth0  proto kernel  scope link  src 62.220.237.114
> 169.254.0.0/16 dev eth1  scope link
> default via 62.236.221.65 dev eth1
Eth1 is your default route, so everything is going to try and go out that way.