Trace Duplicate IP address

[StellaYin5]

Hi everyone,  lately my users reported that there may be duplicate ip in our network that is causing them cannot reach the proper destination. Our company is Canada wide, and be honest, the document of the infrastructure is not 100%. Therefore I cannot verify and make sure that there is no overlap subnet, and cannot check all the DHCP server ip assignment ranges. Yes, but our network team need to resolve these problems.

May you advise me what should I do to find out is there duplicate ip in our network.  Is there any commane that I can use to trace.

thanks in advance

[lgijssel]

Hi Stella,

Duplicate ip's are typically not related to dhcp.

If you could track the duplicate by checking dhcp leases, it means you have overlapping ip subnet ranges.

That's not quite the same as a duplicate ip.

No matter how large your network is, you should at least be able to detect overlapping subnets.

You do not need any specific tool for this, the sh ip route command will do the trick, provided you know how to interprete the output.

regards,

Leo

[StellaYin5]

Thank you Leo. I will check the sh ip route output see if there is overlapping subnet.