Finding which switch and port an end user IP is connected to in a large LAN with multiple switches involves a series of steps using network tools and commands. Here’s a step-by-step guide to trace the IP:
Step-by-Step Guide to Trace an IP Address
1. Identify the MAC Address of the IP
First, you need to find the MAC address associated with the IP address. You can do this from a device that has connectivity to the IP, such as your computer or a network management system.
On a Windows machine:
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arp -a <IP_ADDRESS>
On a Linux/Unix machine:
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arp <IP_ADDRESS>
This will return the MAC address associated with the IP.
2. Log into Your Core Switch or Router
Connect to the core switch or router where you have the central view of your network.
3. Find the MAC Address in the ARP Table
Use the ARP table on your core switch or router to see which interface the MAC address is associated with.
For Cisco devices:
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show ip arp | include <MAC_ADDRESS>
This will give you the VLAN and possibly the physical port where the MAC address is located.
4. Trace the MAC Address through the Network
You now need to trace this MAC address through the network switches. Start from the core switch and work your way through.
On a Cisco switch, use:
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show mac address-table address <MAC_ADDRESS>
This command will tell you which port the MAC address is associated with on the switch. If it points to an uplink port, move to the next switch in the path and repeat the command.
5. Repeat the MAC Address Lookup
Continue using the show mac address-table address <MAC_ADDRESS> command on each switch along the path indicated by the uplink ports until you find the edge switch where the MAC address is located on an access port.
6. Verify the Switch and Port
Once you find the switch and port where the MAC address is directly connected, you can verify by checking the ARP table on that switch.
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show ip arp | include <MAC_ADDRESS>
And check the interface details:
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show interface <INTERFACE_NAME>
This should give you the definitive information on which switch and port the IP address is connected to.
By following these steps, you should be able to pinpoint which switch and port an IP address is connected to within your LAN network.
