[lvs-users] Error on lo after adding IP

Gary Smith gary.smith at holdstead.com
Mon Apr 26 14:16:00 BST 2010

> Don't use the network-scripts file to configure the loopback adapter. It
> will send out an unwanted arp broadcast to determine if the address is
> already in use (in the case of LVS-DR, it probably is) and refuse to
> come up. Also, the arp table on other nodes will be incorrect since the
> MAC address associated with the VIP should only exist for the interface
> configured on the director.
> Configure the loopback device by putting these lines in
> your /etc/rc.local file :
> # solve the ARP problem
> echo 1 > /proc/sys/net/ipv4/conf/lo/arp_ignore
> echo 1 > /proc/sys/net/ipv4/conf/eth0/arp_ignore
> echo 2 > /proc/sys/net/ipv4/conf/lo/arp_announce
> echo 2 > /proc/sys/net/ipv4/conf/eth0/arp_announce

I vaguely remember doing this some time ago on another ipvsadm cluster.  I'll try it out on the test boxes this week.

> # Bring up loopback interface
> ifconfig lo:0 broadcast netmask 0xffffffff
> up
> You can check if you configured it correctly by doing an 'arping VIP'
> from a client (not the director / realserver!) and watching the output.
> You should see replies coming from one MAC address. This would be the
> MAC of the interface on the director that's serving the VIP.
> (i should really make a template from this mail ...)

Or put it on the FAQ page.  I did look through the documentation, I just didn't find anything on the subject.  

> Léon

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