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Old 03-11-2006, 11:43 AM   #1
edman007
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Switch Hell...NFS and degrading performance with gigabit switched


can someone please tell me what is happening on my network with my switch, i am trying to upgrade to gigabit, so i'm starting off by connecting my clients to a gigabit switch witch is connected to a NFS/router with a gigabit card (later upgrading to gigabit clients), i need the gigabit because i'm booting most of the clients off the NFS, my old switch is great, but its only 100Mbps and 8 ports, its a Linksys ezxs88r v2, so to upgrade to gigabit i choose the D-Link DGS-1016D, no for some reason when i plug the server into this switch i get NFS speeds of around <100KBps, but when plugged into the old switch i get speeds of 4MBps+

on the gigabit switch even when i force the server (the only gigabit thing connected) into 100Mbps like all other things connected i still get this unbelivbly slow connection (enough to prevent the NFS boot from working at all), `netstat -in` also shows me that switch is not dropping a single packet, this leads me to belive that it has something to do with flow control (which i read can limit a gigabit thing to the speed of the slowest thing connected), but then why is it limiting to <100KBps or less (usally something like 15KBps)? the slow down from flow control limiting my gigabit to 100Mbps speeds is something i don't mind, as i see that problem going away as more clients get gigabit nics

now for the really strange thing, if i connect my old switch (the linksys) between the gigabit switch and the server, then everything runs just fine, but this makes it impossible to use gigabit on the server, and i don't think its because the server is now in 100Mbps, because i have tried forcing the server into 100Mbps when plugged into the gigabit switch and it didn't help, not even at 10Mbps

BTW, the server is a Quad 500Mhz Xeon with 4G ram, intel gigabit card, and 8 drive 10K SCSI RAID 0, and top shows zero stress on the server, so its not the bottleneck

so what is causing this, is it really the switch, is there some way to work around this to get any speed >100Mbps, will i have to get a new switch to fix this? if so what features would be needed to fix this, any recommendations, both switches have little documentation on their exact specs and it makes them hard to compare
 
Old 03-12-2006, 11:45 AM   #2
Brian1
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Not sure but maybe an issue with the nics module or the nic itself. Have you tried a differnet brand gigbit nic?

edit:
Try using a crossover cable between the server and one of the machines. If it works fine then I would say it sounds like a switch issue. Also in the test use the cable that is currently connected to the server and same for the workstation. Might be a cble issue.
edit:

Brian1
 
Old 03-12-2006, 04:10 PM   #3
edman007
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it was the network card, i have always had excellent driver support for intel stuff so i kinda figured it wasn't it, then i removed the driver from the kernel and used the ones from intels site and it just works now..well its working now
 
Old 03-12-2006, 05:22 PM   #4
Brian1
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Glad to see you have it going. What kind of speeds do you get with that setup?

Brian1
 
Old 03-12-2006, 06:49 PM   #5
edman007
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excellent, as for numbers, i havent measured them yet (will do soon), but i started Open Office and then netbeans on multiple computers simultaneously and noticed very little reduction in speed (the clients are only 100Mbps), it feels like they are running off laptop drives, so its noticeable, but very usable, in fact i booted a laptop off the network and it is faster then using the drive
 
  


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