HA bonding using ARP monitoring

[Pete Wright]

Hi All,
	I've been noticing an issue on a couple boxen I have running Centos4.1, 
here is the uname -a:
Linux xxx 2.6.9-11.ELsmp #1 SMP Wed Jun 8 16:59:12 CDT 2005 x86_64 
x86_64 x86_64 GNU/Linux


I am defining the bonding kernel object as such in our modprobe.conf:

options bond0 mode=1 arp_interval=500 arp_ip_target=<gateway.ip>

we are bonding between two devices, and basic networking and failover is 
working correctly.  I can disable one link and packets pass through the 
second interface as expected.  The problem at hand is that it seems the 
slave device is flapping.  I have checked our switches that this device 
connects to and do not see any errors there.  The ports are not loosing 
link.  These are the messages in /var/log/messages:

<snip - sorry for wrapping>
May  7 04:02:46 critblade204 kernel: bonding: bond0: backup interface 
eth1 is now down
May  7 04:02:46 critblade204 kernel: bonding: bond0: backup interface 
eth1 is now down
May  7 04:02:47 critblade204 kernel: bonding: bond0: backup interface 
eth1 is now up
May  7 04:02:47 critblade204 kernel: bonding: bond0: backup interface 
eth1 is now up
May  7 04:02:48 critblade204 kernel: bonding: bond0: backup interface 
eth1 is now down
May  7 04:02:48 critblade204 kernel: bonding: bond0: backup interface 
eth1 is now down
</snip>

It seems that this was happening for several day's while the machine was 
inactive (it is a development box not in production yet).  I ssh'd into 
the box today and it seems to have stopped flapping for the time being.

Any help would be appreciated, and if anyone needs more info or trouble 
shooting data I'll be more than willing to help with that.

Thanks,
	Pete Wright





--
Peter Wright
Systems Administrator
Sony Pictures Imageworks
wright@xxxxxxxxxxxxxx
www.imageworks.com

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