Network dies when one computer shutsdown?!

[applebyter]

I've got an odd problem with my home office network. When one particular desktop computer shutsdown the entire network seems to die.

The network consists of a Netgear WNDR4000 wireless router attached to a Motorola broadband cable modem. There is a Netgear GS108T switch and a Netgear GS108 switch. There are a number of wired and wireless devices connected to the network, including a ReadyNAS Ultra 6.

The problem has only started after I replaced a faulty GS108T switch. The network was working fine with the previous GS108T switch and all other devices. It was also working ok when the GS108T switch was out of the network while waiting for a replacement. The replacement GS108T is a version 2, while the original one was a version 1.

The computer that seems to cause the problem has 2 wired LAN connections. One to the GS108T and another to the WNDR4000. I have jumbo frames enabled on the LAN connection to the GS108T but not to the WNDR4000 (it doesn't support jumbo frames).

The GS108T is connected to the GS108 plus other computers and with one LAN connection to the Ultra 6. The WNDR4000 is connected to a network printer (a Xerox DocuPrint C2535A), the Ultra 6 and one other computer.

When the computer in question is shutdown the entire network (both wired and wireless) seems to die. I can't access either local devices or access the Internet from anything when the one computer is off. Some devices will lock up and need to be rebooted once the computer is on again and the network is working. (Specifically a Logitech Squeezebox Touch.)

Any ideas of what might be causing this problem and how to get the network to work correctly without having to leave one computer running constantly? Could there be some setting in the replacement GS108T that's causing this? Could there be some conflicting setting between the GS108T and the one computer? Any ideas greatly appreciated.

Thanks.

 

[TonyH]

Hi,
May be network is in hung or locked up state? Any light is blinking or brighter or dim, any thing unusual observed? If two switches are switched around in position? Another idea to narrow down the cause of problem... just unplug the cable from the PC and turn it off?

 

[coxhaus]

You need to plug your switch directly into the router and not go through your PC.

 

[applebyter]

Ok, I unplugged the two LAN connections to the computer and the network stayed up for about half an hour. I then shutdown the computer and plugged the LAN connections back in and the network stayed up with the computer turned offer for about 9 hours.

Sorry, I didn't clearly state that the GS108T is connected to the WNDR4000 and the GS108 is connected to the GS108T. It also wouldn't explain why wireless Internet access dies when the computer is turned off. Computers and devices still get a wireless signal but can't access things like the Ultra 6 or the Internet.

 

[coxhaus]

I would drop down to one NIC per workstation. I don’t think there is any reason to run multiple NICs for a network your size. Multiple NICs are a potential problem as a lot of consumer gear cannot handle it.

I would also try running without jumbo frames and see if it helps. You can always put it back.

Hopefully making changes something will come to mind.

 

[TonyH]

Hi,
Please keep in mind, turning the PC power off by switch and unplugging power cord
is difefrent. When turned off some power is still alive inside the PC.

 

[applebyter]

True, but in all cases I've turned off the PC by shutting it down and leaving it plugged into power.

The latest test was to unplug both LAN cables and then shut down the PC and plug one back in (the one connected to the WNDR4000). The network continued to work when the PC was disconnected from the network and when the PC was shutdown. I then shutdown the PC leaving the one LAN cable still connected and the network still seemed to work. I'll repeat that and leave the PC off for several hours to see what happens.

I'm both frustated by the situation and curious. I know more than enough about networking protocols to know that the network set up I have should work.

PS I hope the floods in Calgary aren't causing you any problems.

 

[TonyH]

Hi,
Interesting to know final outcome of this problem. My house is on higher ground looking down the Bow river but golf course below is a total mess. Already clean up, rebuilding is in
motion throughout the city. Thanks for your thoughtfulness.