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aerofly5
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PostPosted: Sat Sep 22, 2012 2:39 am    Post subject: Slow Network Switching Reply with quote

I know this isn't really the place for this kind of question, but I thought this would be one of the best communities to consult regarding this issue.

I have a Netgear FS108 network switch that connects my server cluster with the rest of the home network. My workstation and servers connect to the switch which has an ethernet cable running to the modem/router, which connects my PC, runs the wireless for the house and is the gateway for the home network. All of a sudden, the switch doesn't transfer more than 3MB/s. After getting the full 100Mb/s for probably 3 or 4 months, one morning I wake up and I only get 16Mb/s from my PC. I powercycled the switch and then only hooked up one server and my workstation and tried to copy the stage 3 tar (as that was the only reasonably sized thing I had convenient) and it maxed out at 24Mb/s. On the switch side of the network I host a website and do some pretty hefty file transfers, so bandwidth for me is of paramount importance.

I doubt its nearing its MTBF, because as far as I know the last owner didn't use it very much and its rated for 168,000hrs of use. Any help would be much appreciated
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eccerr0r
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PostPosted: Sat Sep 22, 2012 2:49 am    Post subject: Reply with quote

The failure mode of my switches that I've seen ended up being intermittent behavior then just not working most of the time (other than if a port stops working). Easiest way to see if it is the switch is to swap it out, or use a crossover cable just to remove it out of the equation.

However when I do see service degradation, it's due to packet loss, not due to outright switching speeds. When you ping another machine, packets would be lost even across the switch.

Every one of my switch/hub failures were just outside of the manufacturer warranty so I had to buy a new one. :( I think they were all within the MTBF period too... Remember MTBF is statistical, not guaranteed life...
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aerofly5
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PostPosted: Sat Sep 22, 2012 2:59 am    Post subject: Reply with quote

I swapped it out with a spare Dlink switch I had (DES-1008D) and it operated at full speed, however it doesn't seem to recognise the modem/router as being a valid node and doesn't bring the port up, thus isolating the cluster from the internet. I tried a ping test just now and I don't lose any packets, however my ping time remains the same as it was (about 250 microseconds) despite the loss in transfer speed. Is it worth buying a new one at this point?
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eccerr0r
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PostPosted: Sat Sep 22, 2012 3:19 am    Post subject: Reply with quote

Does the bad switch work properly without the modem/router connected? (or is it not being detected because of MDII/MDIX/MDX issues?)

I don't know of all failure modes of switches. All I know is that I had two 8-port switches (one noname 100Mbit and one SMC 1Gbit) fail and their failure mode was severe packet loss. Now that I had those failures I keep a 8-port spare switch (replaced with another 1Gbit switch, D-Link) in case the central switch dies again, the downtime was aggravating. Oddly enough both switches that died were serving the same function - my central network switch that connects the main part of my network...

The D-link is #3 in that spot. I hope it doesn't break... I think it's about 3 years now. The other two lasted about 3 years a piece too...
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aerofly5
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PostPosted: Sat Sep 22, 2012 3:43 am    Post subject: Reply with quote

No, the speed remains the same without the router hooked up. And, not that I have much experience with this sort of thing, but 3 years seems too short. Is it all due to the fact that they're just consumer switches? Replacing a room full of switches ever few years doesn't seem very economical in the case of some of those big server rooms and computing clusters.

I have two old 16 port rack-mounted Bay Networks ethernet switches, but I can't keep them cool enough. After 5 or 6 hours of operation (using only the 3 internal 60mm chassis fans), the speed is no better than my current (broken?) switch... Not to mention the noise the thing makes, which while I like, makes it hard to sleep in the same room with them
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eccerr0r
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PostPosted: Sat Sep 22, 2012 8:18 am    Post subject: Reply with quote

It may very well be due to these being consumer grade switches, but these aren't being used in a datacenter... Well, not a mission critical one, just a bit annoying if they break. Alas none of my equipment is datacenter quality really, it's just not cost effective for a home network. Then again, I did not expect networking equipment to fail, they have _never_ failed on me before.

The first switch that died on me had a fan and I know I've had to clean it and unseize the fan multiple times. Not sure when it decided to give up. The SMC was a fanless, but it also succumbed. The third, the D-link, is also fanless. I just hope it lasts much longer than the other two...

I just have a lot of bad luck with:

Networks hubs and switches (either bad ports or device failure)
Discrete Graphics cards (several burned out)
Power supplies (though recently the failure rate has subsided after buying slightly higher quality units)
Hard drives (though recently the once massive failure rate has gone down, was losing about 50% of my disks every year)

Now that I've added a new technology - SSDs - to the mix, I really wonder what the shift will be... back to mass storage device failures? :(
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