Baffling standard star network

Nefarious

Nefarious

Nefarious

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Joined
1 Aug 2003
Posts
1,053
My first thought was interference, but people swear blind that it's not.

The network was working fine this morning and then it suddenly ceased. We reset the router, reconfigured it, the router connected to the internet and all was well with the world, but as soon as it was linked to the rest of the network, the router was no longer accessible and internet connectivity dropped.

My only thoughts at the moment is that someone must have changed something, I just can't begin to work out what.

Any ideas?
 
what was the last bit of kit to be introduced to the network before this started happening?
 
Those were my two thoughts as well, that there was an odd bit of kit or an erroneous crosslink between the two switches but no-one is admitting to have altered any of the kit.

Sorry for the lack of information, I'll flesh it out a bit.

There network is a series of runs from the main office space to a patchpanel in a server cabinet. There is a cable modem and cable feed in the server cabinet which uses a CAT6 run to the main office space where it goes into the WAN port of a wifi router. The router then has a CAT6 run from its network back to the server space where it goes into a switch, that switch has a crosslink to another switch and all devices plug into these two switches.

The router dropped out yesterday and after a reboot failed to help, I got them to do a hardware reset. Went through all the configs and the router seemed to be correctly configured and reliably provided wifi internet connection, but as soon as I reconnect its link back to the switch, everything stops working.

Any ideas? The only thing I can think of is that the cable modem has held onto a registration of something else and it's somehow causing a conflict. I have no idea how that would happen or how it would cause a problem, but it's all I've got.
 
check that the cable modem and the router do not share the same IP address on the local network,

if they are both 192.168.0.1 then that will be the problem so changing one of them to 192.168.1.1 should solve it but keep a record of what IP's you are changing and where and when so you can revert if you choose to later on.
 
Turns out that it was a crossloop issue. Someone had tried to connect and SIP phone by plugging both the LAN port and PC pass-through port of the phone into the network..... and these people are apparently allowed to go to the loo unattended.
 
Told you. I found out the hard way by unplugging then reconnecting 96 cables. It was the 93rd port connected to the 94th in a remote meeting room.....
 
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