How Find Switch?

[dxtrgerry]

So, previously I had a static IP address I could point putty at that would SSH just fine. I verified the address in a Show Run form I copied two days ago, so I'm not crazy. The config was written to memory multiple times so it's not that.

Today, after powering the switch stack down and back on again it.... doesn't work. I can't find the switch anywhere. I know it works because the rest of my network does but SSH is broken. Already tried running network scanners, no dice. How do I find my switch now? Lets assume hard resetting the stack is a non-starter and that I don't have a console cable.

[Richard Burts]

We do not have much information to work with to help you with your issue. As a start, can you tell us about the topology of your network? How big is this network? How many switches? How many routers? What is this switch connected to? Where are you in the network, relative to the problem switch? (are you in the same subnet as the switch, are you 1, 2, ? hops away?)

If you attempt traceroute to the switch what is the last hop before the problem switch? Can you access the device at that last hop? If so what is the output of show cdp neighbor detail on that device? If you attempt to ping that switch, can you then  check the arp table on the last device to respond and see if there is any entry for the problem switch?

[Reza Sharifi]

Today, after powering the switch stack down and back on again it.... doesn't work.

If the users can connect to the switch but you are not able to access it via SSH or Telnet, then there is a good possibility that the SSH key got corrupted during the power cycle and the SSH configuration needs to be deleted and redone. To access the switch, you need a console cable. 

HTH

[MHM Cisco World]

reboot can delete the Key

try generate new RSA key

MHM

[Karsten Iwen]

You should get a console cable. You will need it in the future again. But depending on the switch model, you can also use a direct USB connection.