Sticky-ARP on 3550 switch

jimb · ‎03-17-2008

I have a customer directly connecting an ASA to our 3550 switch on an L3 interface. When he attempted to install a differint ASA with the exact same config and OS version, he could translate addresses via PAT, but his published Web Sites would not come up. We can clear the arp cache to correct the problem, but I am curious about the relationship between sticky-arp and Layer 3 interfaces on the 3550. Does the 3550 apply sticky-arp to Layer 3 interfaces as well as PVLANs?

mchin345 · ‎03-21-2008

For security reasons, sticky ARP entries on the Layer 3 interface do not age out. Connecting new equipment with the same IP address generates a message and the ARP entry is not created. Because the ARP entries on the Layer 3 interface do not age out, you must manually remove ARP entries on the Layer 3 interface if a MAC address changes. Unlike static entries, sticky-ARP entries are not stored and restored when you enter the reboot and restart commands. You can enter the ip sticky-arp ignore command to overwrite the PVLAN sticky-ARP global configuration on a specific interface.