Q: Last night, my week old Linksys 8-port switch went one hundred. At that time there were two machines connected. It was registering insane traffic (flashing LED activity) on both machines, but a tcpdump was empty. I have a machine disconnected from the switch, and the remaining ACT LED is still going strong (again, no traffic tcpdump) 0.
I forgot what I was trying at that time, but the least understood cycling power on the switch, perform / etc / rc.d / init.d / network start on the Unix box, reconfigure TCP on windows box, and testing of all cables and network cards involved in a laptop.
Long story short: it works now, but this is very disturbing. Is this something that is probably the fault of the switch, or is there something else wrong? If its a problem with the switch, I think I will return. Would you recommend staying with Linksys or 3Com goes with (the one Im looking for approximately 40% more expensive)?
http: / / = www.3com.com/products/en_US/detail.jsp?tab=featuresu0026pathtype Purchasing u0026 sku = 3C16791-US http://www.linksys.com/products/product.asp?grid=34u0026scid=31u0026prid = 36
Thanks!
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Re:It turns out heat was the problem. I'm not sure why, but the switch was overheating. There was a faint smell of burning electronics and the case of the switch was very hot to the touch (think CPU heatsink). That was obviously causing the routing malfunction, phantom traffic and burning lights, disconnected machines, etc. I replaced it with a 3com, which is doing fine for the moment. Thanks for the help in diagnosing!
My Traffic Jam
Re:Originally posted by: guy
Maybe the traffic isn't TCP.
Do you have IPX, Appletalk, or any other protocols at that level enabled? Some of them have "heartbeats" where they send a broadcast packet a couple times a second.
Download a packet sniffer (like Ethereal (http://www.ethereal.com/)), and find out what the traffic is. Then you'll know, and won't have to guess.
Internet Traffic Pump System
Re:Originally posted by: guy
Sorry if I wasn't clear. While there was traffic according to the activity LEDs, no traffic could actually get through. My DHCPing Windows machine went from a 192.168.x.x to 169.254.x.x. So the switch be scrood. It actually did the same thing again tonight. RMA, here I come!
Any ideas what I should replace it with?
same model?
-edit- a whole lot of conditions could cause what you're seeing, one of which is a malfunctioning switch.
The Traffic Pump System
Re:Sorry if I wasn't clear. While there was traffic according to the activity LEDs, no traffic could actually get through. My DHCPing Windows machine went from a 192.168.x.x to 169.254.x.x. So the switch be scrood. It actually did the same thing again tonight. RMA, here I come!
Any ideas what I should replace it with?
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Re:Maybe the traffic isn't TCP.
Do you have IPX, Appletalk, or any other protocols at that level enabled? Some of them have "heartbeats" where they send a broadcast packet a couple times a second.
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Re:guy: actually, no i'm not getting any traffic when it goes haywire. first post said the tcpdump was returning nothing… hence my alarm.
guy: hmm ok i guess i better return that thing then =P
anyone in IT have extensive experience with these kinds of unmanaged switches? I'm looking for recommendations…
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Re:I had a similiar problem with a Linksys Router. It showed the same symptoms as your Linksys switch. It eventually died shortly after that.
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Re:so the switch is still working fine (90 mb) when this happens?
sounds like everythign is a-ok then.
you know it coudl be a NIC going haywire and sending out lots of information thus the switch is correctly showing traffic.
the real test would be throwing a 3rd computer on there and seeing if the traffic casues problems.
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Re:not noticeably. When it came, i clocked the transfer between arbitrary ports at around 90Mbit … so not bad.
The computers can communicate with little trouble over a crossover, so i doubt it's the computers themselves that are at fault, but who knows.
The Google Traffic Pump System
Re:guy has the right idea. diconnect all when it happens next see if its bad.
otherwise its just the 2 pc communicating with each other. is it slowing down the communcatins at all?
Re:Yeah I just have 2-3 machines on right now. I got it with room to expand in mind. A crossover could work otherwise. =P
Hmm ok. Thing is, it's not infant death. The switch appears to work now! Someone suggested it might be due to heat, but I doubt that. It has plenty of clearance, and the ambient temp can't be that bad. Very strange. Thanks for the suggestions. Any other ideas?
Re:Next time you have trouble, disconnect BOTH PCs – all cables in fact. If at that point you still see activity on the switch, it's bad and should be replaced. Infant death in particular is a known failure mode of all electronics.
Linksys is not the highest quality switch manufacturer out there, but they're not bad. All switches have some failure rate. I don't believe that 3Com will be that much better. A lot of people have Linksys switches that work for years.
Re:it was jsut the two computers connected to it? nothign else?
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