Cisco 4500M Command Reference Manual page 511

Chapter2 Cisco IOS Commands for the Catalyst 4500 Series Switches
Layer 2 traceroute supports only unicast traffic. If you specify a multicast source or destination MAC
address, the physical path is not identified, and an error message appears.
The traceroute mac command output shows the Layer 2 path when the specified source and destination
addresses belong to the same VLAN. If you specify source and destination addresses that belong to
different VLANs, the Layer 2 path is not identified, and an error message appears.
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. If the VLAN is not specified, the path is
not identified, and an error message appears.
The Layer 2 traceroute feature is not supported when multiple devices are attached to one port through
hubs (for example, multiple CDP neighbors are detected on a port). When more than one CDP neighbor
is detected on a port, the Layer 2 path is not identified, and an error message appears.
This feature is not supported in Token Ring VLANs.
Examples
This example shows how to display the Layer 2 path by specifying the source and destination MAC
addresses:
Switch# traceroute mac 0000.0201.0601 0000.0201.0201
Source 0000.0201.0601 found on con6[WS-C2950G-24-EI] (2.2.6.6)
con6 (2.2.6.6) :Fa0/1 =>Fa0/3
con5
con1
con2
Destination 0000.0201.0201 found on con2[WS-C3550-24] (2.2.2.2)
Layer 2 trace completed
Switch#
This example shows how to display the detailed Layer 2 path:
Switch# traceroute mac 0000.0201.0601 0000.0201.0201 detail
Source 0000.0201.0601 found on con6[WS-C2950G-24-EI] (2.2.6.6)
con6 / WS-C2950G-24-EI / 2.2.6.6 :
con5 / WS-C2950G-24-EI / 2.2.5.5 :
con1 / WS-C3550-12G / 2.2.1.1 :
con2 / WS-C3550-24 / 2.2.2.2 :
Destination 0000.0201.0201 found on con2[WS-C3550-24] (2.2.2.2)
Layer 2 trace completed.
Switch#
This example shows the Layer 2 path when the switch is not connected to the source switch:
Switch# traceroute mac 0000.0201.0501 0000.0201.0201 detail
Source not directly connected, tracing source .....
Source 0000.0201.0501 found on con5[WS-C2950G-24-EI] (2.2.5.5)
con5 / WS-C2950G-24-EI / 2.2.5.5 :
con1 / WS-C3550-12G / 2.2.1.1 :
con2 / WS-C3550-24 / 2.2.2.2 :
Destination 0000.0201.0201 found on con2[WS-C3550-24] (2.2.2.2)
Layer 2 trace completed.
Switch#
78-16201-01
(2.2.5.5
(2.2.1.1
(2.2.2.2
Fa0/1 [auto, auto] =>Fa0/3 [auto, auto]
Fa0/3 [auto, auto] =>Gi0/1 [auto, auto]
Gi0/1 [auto, auto] =>Gi0/2 [auto, auto]
Gi0/2 [auto, auto] =>Fa0/1 [auto, auto]
Fa0/1 [auto, auto] =>Gi0/1 [auto, auto]
Gi0/1 [auto, auto] =>Gi0/2 [auto, auto]
Gi0/2 [auto, auto] =>Fa0/1 [auto, auto]
Catalyst4500 Series SwitchCiscoIOS Command Reference—Release 12.2(18)EW
) : Fa0/3 =>Gi0/1
) : Gi0/1 =>Gi0/2
) : Gi0/2 =>Fa0/1
traceroute mac
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