How to find which port on the switch that it connected with Mac address?

[kianaun]

Hi,

I am trying to find which port of the switches it connected to thru mac-address?

I am able to get the mac-address from the ip address when i do

"show ip dhcp binding snooping" at the core switch.

But when I move on to the Edge switch to check which PC with this Mac address connected to the port,i returned with no result.(onli trunk port result)

I use sh ip arp | inc 000d.60cb.445d

but didn't give me which port it connected to.

How to solve this problem?

thanks!

KL

[ankurbhasin]

Hi KL,

If you are already on the edge switch you can run a command "sh mac-address-table address " and it will give you the port number.

Incase you get a port which is a trunk port that means the end device does not exist on this switch and exist on some downstream switch. So you can just find out the ip address of the downstream switch with "sh cdp neigh detail" command and connect to that downstream switch and then again issue the command "sh mac-address-table address " and check the port number and follow the above steps till the time you get the switch on whcih end host is connected.

HTH, if yes please rate the post.

Ankur

[nbhandarkar]

Why not try the "show mac address-table dynamic" or the "show mac address table dynamic address 000d.60cb.445d" command.

This is definitely give you the port number to which it is connected to.

Pls do rate all helpful posts.

Thanks

[kianaun]

Thanks Ankur,nbhandarkar.

But if the cdp is disabled, any other ways to do it?

I have tried to search at all edge switches with the specified vlan but seems like still returning me the trunk port result..:(

Need you guys assistance again..

thanks!

KL

[ankurbhasin]

HI KL,

If you are getting that mac learned on trunk port for sure there is some downstream switch connected to that trunk port.

Now if CDP is disable you cannot find easily which is the switch connected to that trunk. If possible can you manually trace the cable to find the switch below and then run the same command to find the port.

You do not have any documents or any topology view which can help you?

Regards,

Ankur

[kianaun]

Hi Ankur,

Thanks for your reply again. I have gone through all the Edge switches and search for that particular PC, but to no avail.

There are only less than 10 edge switches,so i search only those switch with tat particular vlan,but could not find that PC as well. :(

[kianaun]

I am also suspecting it could be a hub that connecting to the port of the switch which hold that specified vlan, and the PC(000d.60cb.445d) is connected to the hub.

Thus not sure how to trace if this is the case.

Any insight?

thanks again.

[ankurbhasin · Accepted solution]

Hi KL,

I do not suspect it a hub because as you mentioned you get the mac learned on the trunk port and if it is a hub trunk cannot be configured on it.

Also incase you reach the last edge switch in which you see the mac address learned for suppose 5 mac address learned on that port and it is not configured as a trunk then it can be a hub connected to that port and then you have to manually trace the cable and I do not thing any other way for that becaise if it is a hub it is unmanagable.

Regards,

Ankur

[kianaun]

PC traced! Ankur, you are the man..! :)

You are indeed right..

Today I will have a good sleep :D

thanks!

KL

[ankurbhasin]

Hi KL,

Have a Nice Sleep ;)

Regards,

Ankur