Network File Transfer Question

[Quasimodo]

So i got 2 computers, sitting next to each other. running thru a netgear router. one computer sucks at downloading bittorrents. (playing around w various versions of linux and need to d/l iso's of the live dvd's). The other does fine (from what I've been able to find out its a Netgear issue w router flooding on torrent d/l's)
The last file I d/l was 4.04GB. It takes like 1 1/2 hrs to then transfer this file across my network from computer 2 to computer 1.
my question is.. at 100mb/s (yes i know megabits not megabytes.. so its 8 bits to a byte so its not equivalent. Don't ask me the math in how many acutal bits there would be in a 4.04GB file) is that a super slow transfer rate?
Even taking into account the overhead of the OS at both ends that seems like an overly long time to transfer the file. Is there a way to log/test connection speed from PC2 to PC1 thru the router?

 

[spidey07]

you can roughly divide by 10 to get a guesstimate. So 10 megabytes/sec, or 600 megabytes/min.

There is a utiliaty called Qcheck that you can use.

Most causes of slow performance are cabling (homemade cable and crimping) or a duplex mismatch. So first off make sure both network cards are set to auto detect speed/duplex on the NIC properties. As far as cable you can swap with one you know is good - ie store bought.

 

[Quasimodo]

So by ur calculation 600MB/min it should take only a few mins to transfer the file not 1 1/2 hrs like its taking.. So likely im getting collisions on the network. I thought having ur nic's set to autosense can cause collisions vs having both cards set to same rate ie 10/100 duplex

Will Qcheck tell me if there are bottlenecks or collisions?

 

[spidey07]

qcheck will pump data as fast as it can and tell you the reading. You can also use windows task manager to graph network throughput.

hard setting network cards speed and duplex is the number one cause of performance problems, well after cable that is. Its called a duplex mismatch where one side of the link is full duplex and the other falls back to half duplex. For example hard setting a NIC to 100/full and the switch will operate in 100/half because autonegotiating failed.

A duplex mismatch is worse than collisions. With collisions it just reduces overall throughput to 30-40%. With a duplex mismatch you get late collsions that are not retransmitted by ethernet and must be retransmitted by IP/TCP. This can effectively drop a 100 Base-T connection to about 3-4 megabits/sec, or 3-4% of what it is capable of.

All network cards really should be set to auto anyway to avoid this common problem.

 

[Quasimodo]

After Googling network collisions I found this article.. Interested in your opinion on the solution the author comes up with

Speed Up Network File Copying in Windows XP

 

[spidey07]

That guy has no clue what he is talking about.

Collisions do not and should not occur after 64 bytes. These are called late collisions and a sign of a very sick network.

Furthermore in a full duplex switched network there are zero collisions. None. They aren't even a concern because it can't happen. In fact with today's switched networks you can have 1000s of computers and not a single collision. Collisions are a thing of the past and really are of no concern today.

The interframe gap was designed for optimal performance on CSMACD (ethernet) LANS. Its real affect is depending on frame size that maximum utilization you can get out of a 100 Base-T ethernet link is something like 95-99%.

It should not be changed.

Furthermore he recommends turning down the TCP window. This severely LIMITS performance as there is little to zero packet loss on a LAN you want the largest TCP window possible - like 65535 bytes. I wouldn't want this guy anywhere near an actual network.

I'm willing to put money that you have a duplex mismatch. Set both cards to auto and see what happens. Make sure to plug and unplug your network card after you do.

 

[JackMDS]

You can try to optimize you TCP/IP Stack. The optimization is geared toward improving the Internet connection, but some of the parameters help to improve LAN traffic as well.

Link to: Optimizing & Measuring the "Speed" of Internet Connection.

http://www.ezlan.net/faq#transfer

:sun:

 

[Quasimodo]

Works for me, since im currently at work I will have to try it when I get home. Would haveing a substandard nic cause any interference or slowdown? I have a kinda crappy kne100tx card in one box. When I look at the Netgear router it seems to constantly be tx/rx but when i run netstat I don't really see anything thats sending data. Would changing nic's help?

 

[spidey07]

Before any radical approaches, check the speed duplex settings on each computer. Should be auto. Forcing them to anything at all can cause the exact symptoms you have.

 

[Quasimodo]

Well after trying all of the above things over the weekend and getting no where fast I got really frustrated. So I swapped out all the cables on my router. Nope no change. Last thing I tried was replacing the NIC card. Bingo. Perfect transfer. Took approx 9 mins to transfer 4.04Gb knoppix live iso to burning p.c.
Thanks for all the suggestions tho. Much appreciated

Q