Layer 3 switch... find mac given IP

mikearamamikearama Member Posts: 749
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
There are only 10 kinds of people... those who understand binary, and those that don't.

CCIE Studies: Written passed: Jan 21/12 Lab Prep: Hours reading: 385. Hours labbing: 110

Taking a time-out to add the CCVP. Capitalizing on a current IPT pilot project.

Comments

  • keenonkeenon Member Posts: 1,922 ■■■■□□□□□□
    sh ip arp

    then you can track the device to the switch, then port its connected to
    Become the stainless steel sharp knife in a drawer full of rusty spoons
  • mikearamamikearama Member Posts: 749
    Brilliant... thanks.
    There are only 10 kinds of people... those who understand binary, and those that don't.

    CCIE Studies: Written passed: Jan 21/12 Lab Prep: Hours reading: 385. Hours labbing: 110

    Taking a time-out to add the CCVP. Capitalizing on a current IPT pilot project.
  • ReardenRearden Member Posts: 222
    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)
    More systems have been wiped out by admins than any cracker could do in a lifetime.
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