ip gratuitous-arps

[Cooky]

Is "ip gratuitous-arps" enabled on Cisco switches/routers by default? (specifically Cat 6500's running IOS 12.2)

We're moving some SVI's from a switch to another one.

Since the servers will have the old ARP/MAC cached in their arp table, we'd like to figure out a way to make the servers learn the new ARP/MAC entry for their default gateway w/o manually clearing arp cache on each server.

Would the switches send gratuitous-arps out to inform the servers of the move of the new SVI's?

Looked up the command in the command reference guide, but it's for router / WAN scenario...it mentions the address pool and clients that connect via PPP...
My scenario is servers connected on the LAN.

http://www.cisco.com/en/US/docs/ios/ipaddr/command/reference/iad_arp.html#wp1013090

 

[spidey07]

I'm almost positive they send one when the interface/SVI comes up. You can force it with "clear int vlan x".

 

[Cooky]

Thanks for the reply.
What if servers are layer 2 hops away from the switch where the SVI's reside?

This is kinda a dumb question, since the gratuitous arp will be broadcast over the trunk ports, but I wanted to confirm...

 

[spidey07]

The arps are only significant to a L2 broadcast domain. Hosts on another subnet don't care or are even aware of the MAC change of the SVI.