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Netgear switches dropping connections

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by adrianc

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My network consists of 25 PCs (win98/2000) and 1 windows 2000 server. I use Netgear FSM 726s switches (3). For some unknown reason the switches just loose all connections. If i reboot them and plug PCs/server in one at a time its fine but then within an hour the PCs drop out again. If i use old d-link hubs the network is ok, but this is not a viable solution. I phoned netgear and they swapped all the switches - but the problem has happened again! No PCs or the server have viruses. the firmware on the switches are up to date. Can anyone help????

3 replies

by sgt_shultz

wow. this is a fun one. so hubs work but switches don't. and it is not hardware.
what else changed? when did this crop up? is this recent installation with this problem?
what else changed? dhcp? dns? wonder if datastorm could do this? can you use netmon tools in win2k server disk (or resource disk?) or something to see traffic.
when pc's go 'off' anything pingable? browsable with unc? what does ipconfig say?
what changed? windows updates? new cables? new nics? new dhcp server? new dns server? new isp?
start log of events.
what is in anybody's event log?
what kind of logging can i do?
am i sure enuf that hubs cure problem that i can put some pc's on hubs and some on switches to 'test' individual groups of pcs...?
how can i affect this problem SOMEhow?
how can i make this problem recur?
how can i make this problem go away (like you did hubs): if i only run 2 win2k machines thru switches all others off network or 'cured' with hubs, will problem go away? then i can add in half and half again until i see i have bad nic or cable somewhere...
i would see if i could narrow it down to os specific, suspecting win98 boxes first...

by lmon

Try changing the firmware version you currently have on the switch. I had a router that would drop my connection all the time, I upgraded the firmware and that solved my problem. and if your unconfortable changing the firmware on your own. Call Netgear they probably will walk you through it.

by jolson

You mentioned that you have three switches. Are any of them connected together in a loop. Draw out how your switches are interconnected. There should never be a situation like A -> B -> C -> A -- This looping situation can wreck havoc on inexpensive switches which do not have Spanning Tree Protocol which automatically prevents looping.

An additional thing that can wreck small switches is Network Annualizing software such as Snort or Ethereal which when used in an aggressive / promiscuous mode can jam the MAC cache in the switch.

Hope that helps.

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