Solved: gratuitous arp and secundary ip addresses

gnijs · ‎03-13-2009

When an interface (SVI or routed) comes up, does a Cisco switch or router send a gratuitous arp to update the arp cache of the hosts on that subnet ? I guess yes (?), BUT does he also do this for each secundary address or secundary HSRP active address that is configured on the interface ?

regards,

Geert

Richard Burts · ‎03-13-2009

Geert

I set up a test of this using a pair of 1841 routers with a secondary address configured on a FastEthernet interface. The test shows that when the FastEthernet interface is taken down and brought up that the router does send a gratuitous arp for both the primary address and the secondary address.

HTH

Rick

HTH

Rick

View solution in original post

Richard Burts · ‎03-13-2009

Geert

I set up a test of this using a pair of 1841 routers with a secondary address configured on a FastEthernet interface. The test shows that when the FastEthernet interface is taken down and brought up that the router does send a gratuitous arp for both the primary address and the secondary address.

HTH

Rick

HTH

Rick

gnijs · ‎03-13-2009

Rick,

Thanks for your test.

Geert