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Gigabit speed problems

Last response: in Networking
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August 13, 2006 3:33:12 AM

I just setup my network with 2 gigabit cards and a gigabit router. The cards are D-Link DGE-530T and the router is a DGL-4100.

When I check the status of both nics they both say 1gbit connection. However, when I transfer a 100meg file between the 2 PCS, I only get 7megabytes/s. Checking to see if it was the hard drives causing problems, I started a second transfer off 2 differen't drives and it moved it up to about 8.5 Megabytes/s.

I don't know what else to do to check. I am using Cat6 cable.

The router has the newest firmware.

Any ideas?

*UPDATE*

I have now gotten it to go 12 megs/s each way when I ran 184 pings to my storage server.

More about : gigabit speed problems

August 13, 2006 5:05:34 PM

Try a direct connet between both computers using a crossover cable. Use a ftp file transfer to see what your speed are.

Do you have the old 10/100 mbps hardware disabled?
August 13, 2006 10:00:58 PM

The computers are about 40 ft apart so for me to create a crossover cable would be a pain. I was hoping to avoid that.

I disabled the 100mbit stuff and still no luck.
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August 13, 2006 10:31:19 PM

Have you tried different ports?

Are your nicks running in full duplex or 1/2?

You can pick up a RG45 coupler, and use a short crossover if you need to.

At http://www.speedguide.com they have a tcp optomizer. You might try.
August 14, 2006 12:48:25 AM

I don't think you need a crossover with most Gigabit hardware.
August 14, 2006 6:29:51 AM

Use full auto-negotiation if you're not already.

Try something like iPerf to see what your network is capable of.

Receiver: iperf -s
Transmitter: iperf -c <target> -f m -l 60000 -t 20 -i 5

If you're getting around at least 50 MB/s (400 Mb/s), then you should probably look at the drives and file transfer protocol next before trying to squeeze more out of the networking. Try local file transfers if you have a computer with more than one drive (ideally with both computers). Try using xcopy. Try some file system read+write benchmarks if you can't do local file transfers.

Try a push instead of pull (if you're using it) for the network file copy.
August 14, 2006 8:38:13 PM

Network speed is Mbps (bits per sec) where xfering files is shown as MBps (bytes per sec), so...

1000Mbps = 125MBps

and many HDs won't transfer faster than a sustained 30MBps, assuming equipment purchased in the last year. PCs not busy doing other things, etc.

That said, 7/12MBps is pretty slow... what are the specs of the slower of the two PCs?
August 15, 2006 7:55:55 PM

hey guys. Sorry i haven't been able to update. I didn't go home yesterday.

The 2 pcs hooked up to the gigabit router are:

1) dual 2400 mps, 1 gig ram, 3 internal, 3 external drives (i had heat issues.. i am TRYING to back these up onto my server so i can just scrap these old drives).

2) 1.8 intel. (i bought the board/cpu cheap as hell from frys.. just to build the pc for storage).. 2 hds based off the board, 2 off a sata card.. (makes all sata). has 1 gig ram.

I'm going to try to mess w/ dlinks software that comes with the NICs. Try to turn on jumbo frames and mess with the buffer size. Hopefully that will help. If that doesn't then i'll temporarily move the 2 pcs together and create a crossover cable. See how that works.

Thanks for your help so far. I'll update again tonight
August 15, 2006 8:11:50 PM

You can't use jumbo frames with that router -- it doesn't support them. Direct cable would. Crossover cabling is probably not needed (with gigabit).

Also, you seem to have PCI HD controllers and PCI NICs -- these will crowd the PCI bus together and reduce the overall performance. But I haven't yet done this myself (because I try to avoid this situation), so I couldn't tell you the specific impact. You should however expect average numbers at best for this reason (around 30 MB/s).

Try to test with HD's that aren't running off PCI to factor out this effect if possible.
August 16, 2006 6:49:43 PM

Quick update

Last night I had time to play with this. I plugged the 2 pcs into eachother and tried transferring. I was able to get 16MB/s then. I checked to see if there was a dif between using the atapi controller hds and the ones that were connected straight to the MB but no difference. I even tried messing w/ the jumbo frames, no difference.

I Tried TCP/IP Optimizer, that didn't do anything for me. Next I am going to bring the server near my other pc and try using a dif brand of cable, see if that helps.

Any other suggestions?
August 17, 2006 1:32:49 PM

Quote:

Try something like iPerf to see what your network is capable of.
September 25, 2006 10:15:34 AM

im not sure why you were asked to link it in crossover typicaly that would be a trouble shoot for none connection through a switch or hub. Your crossover connnection is going to be considerably faster since it doesnt have to go through a switch and wont be relavent if your trying to see how fast your connection will be through your switch. Like what was statedbefore 1024 / 8 = 128 would be the true network speed since networks work in bites not bytes (bytes being 8 bites) Then you have to subtract protocal handling which is from windows and your router. at vary max you would be able to atain 80MB out of a 1gig network interface add about 20% over head and thats what you should expect assuming your computer can push that much info. Like what was said your connection is still a bit slow but i have a feeling it has more to do with your computers ability to send the data.
September 25, 2006 11:05:59 PM

I copied a large file (Windows Vista Preview ~3 Gb) from computer to computer through a router that supports jumbo frames (Netgear GS108).

Computer #1 was a Athlon 64 3000+ with 1 Gb of memory and a standard 7200 RPM drive. The motherboard was an Nforce 4, so I used it's built in Gbit adapter. I used Windows XP Pro.

Comuter #2 was a Celeron 600 with 512 Mb of memory, similar hard drive, Windows 2000, and a Netgear GA311. I selected jumbo frames, although I think the GA311 doesn't support 9K frames.

I set computer #1 to use 7.5k frames due to the limitation of the GA311. (or my preceived thought that it was limited).

Anyway, when I transferred the file from #1->#2, I got about 250 Mb/s and when I did #2->#1, I got about 350 Mb/s. I used Cat 6 jacks, and patch cords. (I have a patch panel, so there are a total of three cords, one from each computer to their respective wall jacks (Levitan brand) and a 1' cord from the wall patch panel to the router.

An interesting fact....if I put a 100 Mb 5 port Linksys router to uplink to my Netgear 1Gb router (using normal frames) and attached computers across both routers...I got very slow acess...and packet errors like you wouldn't believe.

You might want to check to see if your transferrs are slow because of some type of packet error...maybe you keep on re-transmitting the same packets.
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