Layer 3 switch... find mac given IP

Hey techies... I'm drawing a blank here.

I know an IP of a remote PC, and I'd like to determine the port it's connected to. The remote switch is layer 2, while my core is layer 3 4506's.

What's the command on my Cat's to find the mac addy, since I know the IP?

Much obliged,
Mike

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Comments

keenon

sh ip arp

then you can track the device to the switch, then port its connected to

mikearama

Brilliant... thanks.

Rearden

Just for reference for people that want specific steps. . .

first ping the device from a router with an interface in that subnet, then do

show arp | include <ip address>

to get the mac address. then do

show mac-address-table | include <mac address>

to find out what port on your router or core switch it is out of. You need to do this until you track it down to which access layer switch it's on and then finally which port on the access switch. After you get past the layer 3 devices, just start with 'show mac-address-table'. Also, remember Cisco mac format aaaa.bbbb.cccc is different than 3Com and other vendors (aa-bb-cc-dd-ee-ff)