Gigabite speeds, not working, help!

January 20, 2009 at 09:00:00
Specs: Windows XP, -
Hi!

I've got two pc's both support gigabite lan. The lan speed is nothing like i was hoping. It works at around 5% of it's full capacity... which is more or less the speed it worked before. I'm not sure what the problem is. Both are setup for giga speeds, the router supports giga speeds and the switch also supports gigabite speeds. I've tried different configurations and it's the same with all of them. What could be causing this? I've run out of ideas...

Router: dlink dir 655
Switch: netgear gs108t
windows xp
2 cat6 cables

Motherboards
dell xps 400
foxconn 945g7md-8ekrs2h


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#1
January 20, 2009 at 12:10:49
How are you testing it? How do you know it's only working at 5% capacity?


>>I've tried different configurations and it's the same with all of them

What configurations have you tried?


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#2
January 20, 2009 at 12:21:17
Check to ensure the NIC's on the PC's are set to "speed = auto".

Try directly connecting the two with a crossover cable and then transfer a large file (over 1 GB). What do you get for a transfer rate?

If the above tests works and both PC's are transferring in the 1 Gbps range try again with both PC's plugged into your 1 GB switch (using regular patch cables). If they transfer at the correct rate then you know everything is ok.

Your setup should look as follows:

Internet >> Router >> Switch >> Clients

I'm wondering, when you're calculating this 5% are you aware there's a difference between bits and bytes? Maybe if you post what you're getting for a transfer rate and then the math you're using to convert, we can figure out if your number crunching is faulty. People often get confused and make simple math mistakes when trying to calcuate bandwidth.


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#3
January 20, 2009 at 12:22:58
Bear in mind that 5% of a 1 Gbit is a lot more than 5% of 100 Mbits. In fact 5% of 1 Gbit is equivalent to 50% of of 100 Mbits so things are moving faster.

The LAN can only transmit data as fast as one computer can deliver it and the other can receive it. There are overheads to consider and processing time that will slow things down.

A Gbit LAN really only comes into its own when you have many computers on the network.

Using just two computers on a Gigabyte LAN is like driving down a deserted six lane highway. You are not going to go any faster than driving down a deserted two lane highway. But you will get to where you are going faster on the six lane highway during the rush hour than you will on the two lane highway.

Stuart


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#4
January 20, 2009 at 13:27:47
I use to get more or less 50-70% of the capacity on a 100mbit lan. Now it's ~5-7% on gigabit lan... not much improvement there. I check the task manager and click on the network tab to show the details, at what speed it's connected at and the % of the capacity thats being used.

I'm afraid i don't have a crossover cable, could a cat5/cat6 cable work to test the tranfer between computers directly?

I've tested it in auto nogotiate but it's still the same. Shows its connected at 1gb. Something is limiting the transfer i just don't know what or why.


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#5
January 20, 2009 at 14:16:36
A gig cable might help (I mean do get one have be sure it is tested.)

Don't expect to see a great improvement with a gig nic over a 100m nic either. Backplane and cpu usage limits speed. At best you might get 30% to maybe 50% of gig speed on a point to point.

See perfmon also for other signs of bottlenecks.

"Best Practices", Event viewer, host file, perfmon, antivirus, anti-spyware, Live CD's, backups, are in my top 10


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#6
January 20, 2009 at 14:54:11
"Don't expect to see a great improvement with a gig nic over a 100m nic either."

Was expecting to get at least improved speeds compared to a 100mb lan. If there was no improvement over the 100mb why call it 1gigbit lan? Weird stuff... Good old marketing...

The computer resources that are being used on both pc's are minimal while transfering and while on idle.

Does anyone else here have any experience with 1gigbit lan on 2 pc, do you get these problems or have you seen an improvement in your lan and by how much over a 100mb lan?


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#7
January 20, 2009 at 14:58:50
I use to get more or less 50-70%

This is typical. Due to overhead and other issues, the best you can hope to get from any connection is around 80% of it's rated bandwidth.

I'm afraid i don't have a crossover cable, could a cat5/cat6 cable work to test the tranfer between computers directly?

No, it has to be a crossover cable. Two things to say to you here:
1) a crossover cable might cost you a whole $5.00
2) Both Cat5e and Cat6 will carry 1000 Mbps so it doesn't have to be Cat6 (more expensive than Cat5e)

I've tested it in auto nogotiate but it's still the same. Shows its connected at 1gb. Something is limiting the transfer i just don't know what or why.

If you're showing 1 Gig all the way through your network then you should be transferring at 1000 Mbps. I will reiterate that it's worth your time and trouble to buy a crossover cable and do a direct PC-to-PC test. Make yourself a file that's several GB's in size (I'd go with about 5 GB's myself). Initiate the transfer and time it with a watch or clock with a second hand. When the transfer is done, post the size of the file and the amount of time to transfer it and I'll do the math for you and let you know what you're getting for throughput.

I recommend going with a larger file because if you only test on a file that's only a few MB's or a few hundred MB's, a 1000 Mbps network will fire that through so fast you won't get an accurate reading on throughput.

Remember, bandwidth is a rating of how much data can flow past a single point in a network in one second. It's not a "speed" rating as is commonly believed. Stuarts's analagy about the 6 lane highway vs a 2 lane highway is apt (and one I often use to illustrate this when explaining to people that don't really understand). The idea being, 3 times as many vehicles can pass any one point in a 6 lane highway in one second than can in a 2 lane highway in the same amount of time.


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#8
January 20, 2009 at 15:06:12
Just thought I'd add a quick note since your last post came up while I was writing mine:

Does anyone else here have any experience with 1gigbit lan on 2 pc, do you get these problems or have you seen an improvement in your lan and by how much over a 100mb lan?

I am a network technician. I work in a university. I support a network spanning 4 cities with multiple sites in 2 of those cities. Our core network is 1000 Mbps running on fibre optic backbone. Our dual redundant Nortel Passport 8600 core switches have a 10 GB backplane and all of our Nortel Baystack 5510 and 5520 switches have 1000 Mbps backplanes and offer up 1000 Mbps to the desktop. So yes, I have experience in a 1000 Mbps environment.

We have gone from a 100 Mbps to 1000 Mbps network during my tenure here. I've helped design and test every aspect of the changeover from the old, slower equipment to the new, faster equipment.

There is indeed a noticable improvement. Especially where you have a lot of bandwidth intensive applications running (and we have several databases running at all times with hundreds of users connected at any given moment during the business day).

Again, I'm not sure what issue you're having but if all your equipment in your network is indeed 1000 Mbps capable then you should be running at 1000 Mbps. If you're not, then you have at least one 100 Mbps device (like a switch) in the mix that is limiting your two PC's, or, you're just misreading your transfer data.

Anyhow, run a transfer test, post the amount of data transferred and the time it took. No approximations please, be precise.


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#9
January 20, 2009 at 15:27:29
It's a mistery that's for sure. I'm sure it's not the router or switch, since i've tested them independently and they both give the same result. It's not the wires, their both cat6 cables and have tested with other cat5 cables, get the same result with both. It's not the resources of the pc's, minimal resources are being used.

The only thing i can think of is that something isn't enable on one of the pc's, some option isn't activated or something isn't setup right.

Big mystery this is.


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#10
January 20, 2009 at 15:40:57
What are the drive specs on each system?

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#11
January 20, 2009 at 15:44:41
Of the nics?

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#12
January 20, 2009 at 15:55:58
"What are the drive specs on each system?"

Do you mean drivers? Or hard drive specs, sorry i'm not sure what your asking for.


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#13
January 20, 2009 at 17:32:42
Disk I/O is the slowest link in the chain when transferring files.

You can also run a packet capture and analyze the traffic to see if there is any dropped packets or other issues that might explain the issue.


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#14
January 20, 2009 at 17:39:45
I see, i'll have a look into that. Thank you!

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