Warning message

  • Cisco Support Forums is in Read Only mode while the site is being migrated.
  • Cisco Support Forums is in Read Only mode while the site is being migrated.


Unanswered Question
Aug 7th, 2006
User Badges:

Need help please. Have 5 Vlans on 2970 switch that is communicating with the 3750 L3 . On the 2970 I need to find out which PC/Computer is connected to lets say port 20 of the 2970. Since 2970 is a Layer 2 switch, how can I achieve my goal , I think MAC address is my answer but I need the IOS commands please. If you can think of some other utilities that would help I apperiaciate it very much. Thank you

  • 1
  • 2
  • 3
  • 4
  • 5
Overall Rating: 0 (0 ratings)
Richard Burts Mon, 08/07/2006 - 18:44
User Badges:
  • Super Silver, 17500 points or more
  • Hall of Fame,

    Founding Member

  • Cisco Designated VIP,

    2017 LAN, WAN


I doubt that you will accomplish this with a single command or by anything on a single box. But I think that you could accomplish it by doing this:

- on the 2970 do show mac-address which should show the layer 2 forwarding table (what is refered to as cam on some other Catalyst switches). Look for port 20 and note the MAC address.

- on the 3750 do show arp and look for the MAC address. This should give you the IP address of the device on port 20.



slavb Wed, 08/09/2006 - 12:38
User Badges:

Rick's right, you will need to chase this on both devices. Try this

2970 - sh mac-address-table interface fastEthernet 0/20

This should provide you with the MAC address. Use this address on 3750 as follows

sh ip arp | include xxxx.xxxx.xxxx

You should see host's ip address.



This Discussion