[DRBD-user] CentOS, eth0, eth1 and arpwatch flip flops

Gavin Henry gavin.henry at gmail.com
Sat Jan 5 01:49:44 CET 2013

Note: "permalinks" may not be as permanent as we would like,
direct links of old sources may well be a few messages off.

> Has anyone experienced this whilst running DRBD over eth1 between two
> CentOS 5.7 servers?
> eth1 is a private IP address, unroutable. eth0 is the public address.
> CentOS will reply sometimes once every 3 days or every 14mins~ saying
> "My public IP is on eth1" to arp requests when it's not, it's eth0.
> This freezes traffic and causes issues. We've looked at arp*
> /etc/sysctl.conf etc. and arptables, but wondered if anyone had a
> recipe?
> We have this already which didn't help as it happened Christmas Eve
> too as we kept eth1 up for a few days to test:
> # For the dual interface - 06.12.12
> net.ipv4.conf.eth0.arp_filter = 1
> net.ipv4.conf.eth0.arp_ignore = 1
> net.ipv4.conf.eth1.arp_filter = 1
> net.ipv4.conf.eth1.arp_ignore = 1
> net.ipv4.conf.all.arp_filter = 1
> eth0 and eth1 are on the same VLAN/broadcast domain, but eth1 is a
> 169.xx and eth0 is a routable public IP.
> We're having to shut eth1 down and bring it up for sync at night.
> Thanks,
> Gavin.

Couldn't get this to work so have had to bin DRBD. Shame.


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