Discover Hubs on a Network

[Yort Mantup]

I have a branch office with a router and switch and two separate switch closets with one switch in each.  Closets are connected via fiber to main room.   I have found there are 5 hubs in the building extending the network runs and some of the hubs are in the rafters.  Is there a way I can find the IP or MAC addresses of the devices plugged into those hubs?  I do not have the MAC address of the hubs themselves.  I am trying to do this remotely.

Thanks             

[Andras Dosztal]

You can check the number of MAC addresses by entering the show mac address-table command in privileged exec mode. There will be one per interface if a host is connected, while multiple on inter-switch and switch-to-hub links.

[Mitchell Dyer]

With the exception of trunk ports is your environment mostly one device per port?

If you aren't using unmanaged or work group switches and you answered yes to the question above you can use the CAM table to see which ports have learned more than one MAC (assuming the hubs have multiple devices connected to them).

Sh mac address-table
Sh mac address-table int

HTH
Mitch

Sent from Cisco Technical Support iPhone App

[Angus Bishop]

Issue the command sh mac address-table in the switch .
Find the ports which has more than 1 mac address learned . The ports with more than 1 mac address will be connected to hub .

Note: if you have ip phones in your network you can get 2 mac in the interface .
In such case use sh power inline command or see the inteeface configuration for voice vlan configuration for confirmation


Sent from Cisco Technical Support Android App

[matthew-frederick]

you can always configure eachport with:

switchport port-security

switchport port-security maximum 3

then see which ports go into and err-disabled state

[Edwin Summers]

I believe that the switchports that are connected to hubs should have also negotiated to a half-duplex state (since the hub results in a shared link).  This may be another way to check in case some of the stations are off or have not "spoken" in a while.

Might even be able to check the switchports for collisions.  Maybe send some broadcast pings to get the fun started.

Good luck!