Trace a MAC address on a switched LAN-Cisco

The Layer 2 traceroute utility identifies the Layer 2 path that a packet takes from a source device to a destination device by using the MAC address tables of the switches in the path. 

traceroute mac source_mac_address destination_mac_address vlan_id 

where the MAC addresses of source and destination are specified together with the VLAN id.

• For Layer 2 traceroute to function properly, Cisco Discovery Protocol (CDP) must be enabled on all the switches in the network.
• It is important to know that the specified source and destination MAC addresses must 
• belong to the same VLAN.
• If the source or destination MAC address belongs to multiple VLANs, you must specify the VLAN to which both the source and destination MAC addresses belong.
• When the switch detects a device in the Layer 2 path that does not support Layer 2 traceroute, the switch continues to send Layer 2 trace queries and lets them time out.
• The maximum number of hops identified in the path is ten.
• Layer 2 traceroute supports only unicast traffic.

Ex:

SW1#traceroute mac 0019.9955.0f60 00a0.6011.aa0b

Source 0019.9955.0f60 found on SW1

1 SW1 (192.168.0.253) : Fa0/21 => Fa0/1

2 SW2 (192.168.0.254) : Fa0/1 => Fa0/27

Destination 00a0.6011.aa0b found on SW2

Layer 2 trace completed

SW1#