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I have an office of 10 desktop computers and 1 server. All of the desktops are connected to a Netgear JFS516 100 Mbps switch. The server and the switch are connected to a Linksys E2000 1 Gbps router. There have been no recent changes to the network, but most of the desktops (a specific few far more often than the others) have been dropping down to 10 Mbps after logging in, mostly in the morning; rebooting seems to fix the problem for the day. Some of the computers, mostly notably mine (which is closest to the switch) almost never experience this problem.

All of the desktops are the same, Dell Vostos with Broadcom NetLink Gigabit NICs, and all have the same configuration. I ran and terminated all of cable (CAT 5e) myself about 4 years ago and recently reinspected the cable visually and electrically: the cables don't look damaged and each of the pairs in the cables are correctly terminated per TIA/EIA-568-B.

I put 3 of the desktops that were encountering this problem on a different switch, but they still exhibited the same behavior. I've been logging the link speed of each computer every 5 minutes for a few days and am unable to see any pattern other than it normally happens in the morning when they first wake their computers from sleep and log in.

I'm at my wits' end, so please suggest anything I can do to find the source of this problem and fix it. Thanks!

UPDATE
It's been one week since I disabled power management so the computers wouldn't go to sleep/suspend mode (they are still shut down at the end of the day). In that time, I have not had any link speed issues on any of the computers. I am still uncertain as to why resuming from suspend would cause link speed issues, especially only in certain sections of the office. My best guess at this point is that possible cable issues (age, interference, distance, etc) play a factor along with suspend in creating the lower link speed. Thank you to those who took their time to help me out!

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Connect one of the problem computers to a switch directly with a short pre-manufactured patch cable and let your tests run over the weekend? –  Zoredache Dec 6 '11 at 18:58
    
@Zoredache The link speed automatically drops to 10 Mbps when the computer is asleep (over the weekend) so I wouldn't get any meaningful data unless someone was using the computer. Maybe I could try swapping a computer that has this problem more often with one that has it less often and look for changes? Thank you for your suggestion. –  Levi Larsen Dec 6 '11 at 19:04
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Just a thought, have you tried disabling the power management? What happens if the computers are never allowed to sleep? –  Zoredache Dec 6 '11 at 19:21
    
@Zoredache I haven't, but I will definitely try this. –  Levi Larsen Dec 6 '11 at 19:31

3 Answers 3

up vote 1 down vote accepted

Sounds like the switch. Netgear isn't known for their quality. Can you swap out the switch? When you said different switch, was it another netgear? Does the netgear have port diagnostics (I'm assuming not.) What does the event log in these computers do?

Another thing to worry about is broadcast storms. Did you recently redo the switches? Are you running spanning tree? Could someone have plugged a loop into your switches?

Wake from sleep mode always seemed like a mess to me (breaks network drives, etc). I typically set it so the PCs never sleep and the network card never sleeps. The PCs are either completely off for the night or always running. No middle ground.

Lastly, have you updated the network drivers lately? You might to give that a try too. Is there a firmware update for your switch? Have you power cycled the switch?

Also, do you have a long cable to test. Maybe your wiring job isn't as good as you think it is.

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The switch doesn't have any diagnostics. I had swapped it out with something generic I had a home, I don't remember the manufacture, but it definitely wasn't Netgear. The event log just reports failed folder redirection when logging in, but I am also seeing "Broadcom NetLink (TM) Gigabit Ethernet: The network link is down. Check to make sure the network cable is properly connected." at 4AM. I haven't changed anything with the network in probably a year. I'm not familiar with spanning tree. I haven't updated the drivers, but I will try that next. Thank you! –  Levi Larsen Dec 6 '11 at 19:13
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Sorry but that's a -1 for the flame bait in your first sentence. On my lifetime I have deployed hundreds of netgear devices, switches, routers, VPN devices, wifi access points. Don't let one persons opinion of one product tarnish an entire brand. –  Mark Henderson Dec 6 '11 at 19:39
    
Netgear devices are often cursed for the wrong reasons. Every hardware part is prone to failure, switches are surely no exception - Netgear or not. But what is true for Netgear devices is that their model line consistency sucks massively. Switches within the same line, even different revisions of the same model will vary greatly in (management) functionality. I have yet to see anything even close to that in any other network hardware vendor's line. –  the-wabbit Dec 7 '11 at 1:55

Link speed is negotiated when the link fist comes up. It sounds like cabling to me. To eliminate this, install a small 10/100/1000 desktop switch at one of the PC's exhibiting the problem and see if the PC maintains a 1Gb link to the desktop switch. Or, get a cable tester and test the cables.

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I haven't tried putting the switch on the other end, so I will try this. Thank you. –  Levi Larsen Dec 6 '11 at 19:26

I doubt it is the issue, but oxidization can make cables get "older" then they should prematurely. Using a Fluke or similar tester will ensure you that the cabling has not deteriorated.

And like DrZaius said, Netgear is known for having poor quality.

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I will start to look around for a Fluke cable tester to rent. Thank you. –  Levi Larsen Dec 6 '11 at 19:24

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