F5 Gratuitous-ARP issue when failover

For troubleshooting I would recommend to run a simultaneous tcpdump on interface "

0.0

" with a filter on "

arp

" on both machines in your device service cluster and to trigger a failover. (Use the "

-s 0

" option for full packet size and "

-w /var/tmp/.pcap

" for dump to file, please)

I.e.

tcpdump -vi 0.0 -c 10000 -s 0 arp -w /var/tmp/trace.$HOSTNAME.pcap

In wireshark you can apply a filter of

arp.isgratuitous

to display G-ARPs only. As written by surgeon, it might happen that due to the pure amount of G-ARPs some might get lost.

Virtual IPs configured in non-locally-attached networks wont send G-ARPs. Instead you can expect seeing G-ARPs for floating self IPs which are used as next hops.

Don´t be irritated to see G-ARPs for local-only Self IPs (especially those to be used for device service cluster configuration heartbeat/config-sync/mirror) as well.

Make sure, not to set the "

link down on failover

" (Device Management >> Device Groups >> : Failover; just leave it in the default setting of "

0.0

") as it might trigger a spanning tree reconvergence after a failover resulting in lost G-ARPs.

Cheers, Stephan