How to trace a MAC address in catalyst 6509

[mudassir]

Is there a way to trace MAC Address.

I always have problem in finding the Designated Root device from the MAC Address. (Designated Root 00-10-0d-b1-78-00)

Cat 6509> (enable) sh spantree 1

VLAN 1

spanning-tree enabled

spanning-tree type ieee

Designated Root 00-10-0d-b1-78-00

MAC address of the root switch for VLAN 1.

Designated Root Priority 8192

Designated Root Cost 0

Designated Root Port 1/1 .

Regards,

[daniel.bowen]

If you would rather just specify the root bridge, instead of finding it and then changing it simply do the following

From the bridge you want to be the root bridge for say VLAN1 type

set spantree root 1

From the bridge you want to be the root bridge for say VLAN 10 type

set spantree root 10

This command automatically changes the switch to the root bridge

Daniel,

[psijnja]

you could try: show cam

[milan.kulik]

This won't work.

Bridge ID's are different from sc0 MAC addresses, so you'll never see them in CAM table. It's also impossible to use l2trace command for this purpose (but it can be very useful for user PC finding, e.g.).

There is one manual way of root bridge finding:

sh spantree

look at the output and find "Designated Root Port" line

telnet to the switch which is connected via Designated Root Port (if you don't know which switch it is, use sh cdp neighbours)

repeat

sh spantree

.

.

etc., etc.,

until you are on the root switch (Designated Root and Bridge ID are the same).

Another way is using some tool, Fluke Networks LAN MapShot, e.g.

Regards,

Milan

[ckolasinski]

Sh cam 00-10-0d-b1-78-00 will show you the port where the mac is coming from,

[milan.kulik]

Have you tried it?

I think you won't see 00-10-0d-b1-78-00 in the cam table at all.

The root switch is using it's sc0 MAC address as BPDU frame source address. sc0 MAC address is different from STP bridge ID.

More: if the switch you are checking is not directly connected to the root the BPDUs are coming from another switch. So the source address of the BPDU frame will be totally different.

Regards,

Milan