Depending on the Cisco platform, sometimes the command is listed in either form. On that device issue one of the following commands (where mac-address is the hardware address from previous step). The output should look similar to below, and give you the mac-address of the device (listed below in bold). Log into the routing device, and issue the following command (where ipaddress is the ip address of the host you are trying to locate: show ip arp *ipaddress* Sometimes it is a ' Router on a Stick', where the Layer 2 VLANs are being trunked up to the router for the Layer 3 decisions. The output should look similar to below, the port you are looking for should be listed as the Destination Port: LYKINS-1861#show mac-address-table address 28cf.da1d.1b05Дestination Address Address Type VLAN Destination PortДў8cf.da1d.1b05 Dynamic 10 **FastEthernet0/1/1**ДЇind out what device is doing the routing for this switch (you may have to look at the network documentation). Show mac-address-table address *mac-address* show mac address-table address *mac-address* The NextHop-Mac address column represents the destination MAC address of the next hop router, which is required as the address used to rewrite the destination MAC address for. This information is generated from the routing table on the MSFC. Example 2 Display MAC Address Table Aging on CatOS-Based. Example 2 shows a sample output where the topology change has set the MAC address table aging to 15 seconds on CatOS-based Catalyst switches. Now issue one of the following commands (where mac-address is the hardware address from previous step). Example 6-89 Displaying the MSFC MAC Address on CatOS Switch-A> (enable) show mls cef mac Module 15. Use the following command to display the current MAC address table aging time on CatOS-based Catalyst switches. Protocol Address Age (min) Hardware Addr Type Interface The output should look similar to below, and give you the mac-address of the device (I've highlighted the mac-address below in bold). Log into the switch and issue the following command (where ipaddress is the ip address of the host you are trying to locate: show ip arp *ipaddress*

In either case, the commands are the same, just run on two different boxes for the layer 2 switch. The output will give you the Vlan, mac address, and port on which it was learned. Check the mac-address table for the mac address in question using the necessary command.

However on a layer 2 switch, you have to log into both the switch and whatever device is doing the routing to locate the port. Now, if the default gateway is a router, connect to the downstream switch. On a layer 3 switch, the port can be found by using a few simple commands on the device. That is to say, is the switch only switching and relaying traffic on to a different device for routing, or, is it doing the routing decisions itself via SVIs (switched virtual interfaces). The answer depends on whether the switch is a Layer 2 or a Layer 3 switch.

Catos show mac address table