Forum Discussion

A_C's avatar
A_C
Network Novice
Hace 2 años

Gateway IP address conflicts

Tmobile Gateway router HHCP seems to be assigning unique IP addresses on network devices but getting network warning of IP address conflicts every few minutes?
  • iTinkeralot's avatar
    iTinkeralot
    Hace 2 años

    You can open a console/terminal and ping the network broadcast address 192.168.12.255 and then check the client's ARP table (command arp -a). That should provide some idea of clients that are up and are responding. If you have set any static IP addresses on the network in the 101-254 range then remove the IP for any client with a static IP in that range and use an IP from 2-100. I am pretty sure the DHCP scope runs from 101-254. I never seen an IP assignment below 101 from DHCP. I can assign and I do assign static IPs below 100 so I am pretty sure it is safe to say it is ok and will not duplicate any IP addresses. You can easily test by pinging an IP address you want to set from a client that is connected with a valid IP address. If there is no response then the IP is probably free, assuming it is NOT part of the DHCP scope.

iTinkeralot's avatar
iTinkeralot
Bandwidth Buff
Hace 2 años

It sounds like that gateway might have some problem possibly. Connect one client only and configure it with a static IP address, 192.168.12.10 with a 24 bit mask 255.255.255.0 and set the gateway IP to 192.168.12.1. Set DNS to 9.9.9.9 if you want or whatever even the gateway IP is fine. A client with a static IP assignment outside the DHCP scope should NOT see an IP address conflict. 

Open a console and ping the broadcast address 192.168.12.255.

Then issue the command, arp -a

See what ARP entries appear. With the single client I would only expect to see the gateway IP. Even if you do not provide the gateway IP address to the client it should be able to receive an ARP response from the gateway. 

That is a rather odd problem to see. IF you have tested with a single client maybe two and no additional switch connected and the problem is still there I would have to suspect there is something strange going on with that gateway. Maybe a reset to factory default and set it up again and then see if the same problem presents again.