TWR router(s) DHCP

Submitted by tarvid on Wed, 09/28/2016 - 10:57
A wireless user called in a panic when his Internet connection went down. Dispatched Ray to the site and suggested bouncing the radio. That means disconnecting the cat5 cable from the POE to the radio, wait 5 seconds, plug it back in, wait two minutes or so. No luck. The POE is inside, the radio is outside. The easiest and least expensive fix to try is replacing the POE. Ray has one in the van and replaces the POE. Yay the Internet comes back up. Not so fast, a few minutes later the Internet is down again. Time to retrieve that POE from the trash. When he tries to browse to the router he does not get the Tenda router he was expecting. It turns out to be an old router previously connected to a Hughes satellite. DHCP is an odd protocol. Both the Tenda and the Hughes router have DHCP servers. When a client on the network requests an address, the first one to respond wins. The Hughes router doesn't know how to get to the Internet so when a client gets an address from the Hughes router, the client can't get to the Internet either. Disconnecting the Hughes router and ... Yay the Internet comes back up. The Tenda gets its IP address from TWR and hands out addresses to the local network. More on networks later.