If this is the case then you won’t need to logon to each switch in the chain to find the port. If you have all Cisco devices and CDP is enabled (it is by default) then there is an easier way to find the devic,e as long as it is local to the first Layer 3 device you logged into (not routed somewhere else). I know by looking at my diagram that this switch is the end of the line so I’ve finally found the switch and port that area1-wks01 is connected to.
Area1-sw2# show mac address-table address 001a.a07f.4a94
So now I need to logon to that switch (area1-sw2) and once again issue the same command. Now once again looking at my handy network diagram I see that Gi0/22 is another trunk leading to another switch. Area1-sw1# show mac address-table address 001a.a07f.4a94 In my case this trunk goes to a switch called area1-sw1 so now I need to logon to that switch and issue the same command. Fine, you can use the command show cdp neighbors to see which switch or router is connected to that port. Don’t have a network diagram or too lazy to find it. A quick look at my network diagram indicates that Gi2/0/25 is a trunk connecting to another switch. Well it’s not quite that simple because I doubt your workstations are connected to you Layer 3 device. Sweet! We see that our workstation is connected to Gi2/0/25. Total Mac Addresses for this criterion: 1 Sw-stack#show mac address-table address 001a.a07f.4a94 We need to search the mac address table to find out which port to follow. I’ll show the hard way first because it’s the way most people do it. Ok, from here there are two ways to find the device the hard way and the easy way. Protocol Address Age (min) Hardware Addr Type Interface By pinging the device it’s mac address will be listed in the arp table. Next we have to find the mac address of the device.
Success rate is 100 percent (5/5), round-trip min/avg/max = 1/2/8 ms Sending 5, 100-byte ICMP Echos to 199.254.7.100, timeout is 2 seconds: The first thing to do is to ping the IP address. In my case it’s a 3750 switch stack that handles routing between the various subnets I have configured. Now it’s time to log into your router or some other layer 3 device in your network.
C:\>nslookup area1-wks01įrom the output you can see that the domain controller that responded to the lookup, the Fully Qualified Domain Name (FQDN) of the device, and its IP address. So the first step is to open a command window and use nslookup. The first thing to do is find the IP address of the device you’re looking for. The network that I manage is disconnected from the internet so I can’t post screen shots, but what you see are recreations of the screen shots I printed. So now I’ve decided to write a good tutorial. I don’t work with network gear very often so every time I need to find out which switch port a device is connected to, I’ll typically have to do a quick search to find the commands.