Win2000 to Win2000 slow LAN connection

[D. Jackson]

Greetings. I have three computers connected via a LinkSys router
(BEFSR41 -- all 100 Mbps connections) -- two Windows 2000 machines and
1 Linux (Mandrake) machine. I currently share directories between
all three computers using MS File and Printer sharing on the Windows
machines and Samba on the Linux machine and have noticed that copying
files between the two Windows machines is painfully slow.

The test: copy a 100 MB file between all of the machines*, **

Win 1 -> Linux : 14 sec ( ~57 Mbps )(expected with TCP overhead)
Win 2 -> Linux : 15 sec ( ~53 Mbps )
Win 1 -> Win 2 : 576 sec ( ~1.4 Mbps ) WHY????

Why the huge discrepancy? I am using UNC paths to copy all the files
(copy file \\computer\dir) and am not mounting any directories
currently.


* Timing was done with a perl script that reads the start time, runs a
task, and reads the end time and reports the timing results. It's
available upon request.

** Another quick timing method is from the command line ( you'll have
to subtract the times yourself though):
echo.|time && copy bigfile \\other_computer\directory && echo.|time


Any suggestions and help would be greatly welcomed!
-dennis.

 

[D. Jackson]

Win 2 -> Linux : 15 sec ( ~53 Mbps )
Win 1 -> Win 2 : 576 sec ( ~1.4 Mbps ) WHY????

Why the huge discrepancy? I am using UNC paths to copy all the files
(copy file \\computer\dir) and am not mounting any directories
currently.

Any suggestions and help would be greatly welcomed!

A solution for those reading: I set the network settings on the two
windows machines to 100 Mb, Full Duplex explicitly (they were set to
auto-sense before) and the speed of transfer now matches the
Win->Linux rates.

The router indicated that all three computers were at 100 Mb, full
duplex previously so I am not sure were the bottleneck was occuring.

-dennis.

 

[Javier Romero]

Dennis,

Sometimes, the auto-negotiation between two devices goes
awry and you end up with a lot of bad frames. This is due
to the fact that the two devices did not synchronize
properly. This situation requires the retransmission of
frames which equals latency issues. I have sometimes seen
this between a certain type of NICs and Switches. I took a
class one on making networks more efficient and it was
stated that many problems can occur from Auto-Negotiation
and to avoid using it. I was told to hard set the data
rates to avoid negotiation issues.

Javier