Identifying an IP address from a port/MAC

[openfield2010]

I've downloaded a few free tools that scans subnets looking for a particular ip but can't seem to find an ip relating to one of our old switches.  The network guy is no longer with us and documentation was a bit crap we discovered after he left and it's one of the remaining question marks we have on the network.

I have a Cisco SG200-26P plugged into port 18 on a Cisco C3650 Layer 3 switch, this is our core switch, and i know the MAC address of the switch in question.  Is there anything that will tell me the ip address of the switch at all?

edit:

Just as a quick edit as something i forgot to put in.  I've done a 'show arp' on the core switch that the sg200 is plugged into and can't find mac address that matches with what it should be. 

[chrihussey · Accepted solution]

Have you tried "show cdp nei detail" on the core switch? That may tell you the IP of the SG-200.

Hope this helps

[openfield2010]

Works, thank you.  I now have the ip address which is 10.14.140.10, this is part of the management VLAN.  Slight change though as i thought it was an SG200-28P, it's actually an SG300-28P.

Now the only issue though is that i can't ping it from my computer on the 10.14.130.0 subnet nor can i connect it via a web browser or an SSH or Telnet from Putty, it just times out.  The switch is working fine, i just can't connect to it from my machine, or any machine, which presumably is why all the software on my computer didn't see it.

Any ideas on the best way to connect to it at all? 

[chrihussey]

It could be a couple of things:

1- It may not have a default gateway configured. Try to ping and connect to it from the local subnet.

2- The management interface is configured in the wrong VLAN

3- Assuming it is a trunk port between the SG300 and the 3650, verify the management is VLAN allowed on both ends, and if so you could try making the management VLAN the native VLAN.

Short of that, you may have to console directly into the switch to see what is going on.

Regards