GARP on 6500 ASA blade

[Marius Gunnerud]

We are planning to migrate a context from an ASA 5550 to Catalyst 6500 ASA blade.  The requirements are to use the same IPs, VLAN interfaces...etc.  This is all fine.  The issue comes with the ARP cache on devices between the firewall and the client.  There are quite a few switches between the firewall and client and not all are under our control.

So my question is, is it possible to issue or force a GARP so that all L2 devices update their ARP tables and we do not have to wait or request the 3rd party to clear the arp cache on all their switches when we cutover?  What would the command be if this is possible?

Thanks.

[mirober2]

Hi Marius,

ASAs (including the ASA-SM) will send a grat ARP on an interface-up event (i.e. boot up, failover, shut/no shut, etc.) for the IP address assigned to the interface. However, the ASA will not send grat ARPs for any global/translated IP addresses used by NAT statements. Given this, it's usually better to clear the APR caches on the connected devices if you see any issues.

-Mike