arp table in routers

[carl_townshend]

Hi all

does a router use an arp table like a pc does, does it initially send out an arp request then once it recieves the answer, does it then cache it in the arp cache? and is this for directly connected devices only ?

[lamav]

A router maintains an ARP table and has entries for directly connected devices as well as next hop addresses for external destinations.

HTH

[dnewell24]

One point I want to expand from lamav's post. Directly connected devices does not mean physically directly connected but all devices reachable via a layer 2 broadcast on that directly connected LAN segment. For example if a switch is connected to a router interface. The router will maintain an ARP entry for every device connected to the switch.

I think each ARP entry is valid for 4 hours.

[lamav]

Good clarification....