Cat2900's: finding MAC address of connected equipment

[mercury01]

Background: lots of Cat2900's, VLAN's & VMPS to tie 'em all together.

When an unregistered PC is plugged into a port - how do we obtian the MAC address of the PC (or any device really) plugged into that port from the switch?

[paddyxdoyle]

Hi,

You can use "show mac-address-table interface int_num" on your switch.

e.g.

#sh mac-address-table interface gi 1/0/5

Mac Address Table

-------------------------------------------

Vlan Mac Address Type Ports

---- ----------- -------- -----

104 000d.60d5.1028 DYNAMIC Gi1/0/5

Total Mac Addresses for this criterion: 1

HTH

Paddy

[sholeh]

Dear Paddy,

I ever tried your way, but it didn't work.

When I tried command" Show mac-address table"

I saw many mac address but when I tried to track this mac address using arp eth_addr nothing came out on the screen....is there any way of finding PC onnected to switch ports ?

Thanks'

Sholeh

[Prashanth Krishnappa]

Switch which is a layer 2 device will not have an ARP entry for all the devices connected to it(but for default gateway). Go to an upstream router/layer 3 switch and issue the "sh ip arp "

[paddyxdoyle · Accepted solution]

I'm confused now :)

If you have the devices MAC address and want to find out which ports it's on then you can do:

show mac-address-table address

If you want to find out which MAC address has been learned on an interface you can do:

show mac-address-table interface

If you want to find a MAC address of a device when you have its IP address, go to the switches default gateway and you can do

show arp | i

or show ip arp

If you want to find the IP assigned to a device by using its MAC address then as pr mentioned above you can do (on the default gateway)

show ip arp

HTH

Paddy