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Speed up network between OS X and Windows XP
Authored by: Shawn Parr on Mar 08, '05 01:30:18PM
This is actually a Win XP bug, and it only happens with specific ethernet adapters. Some drivers under XP do not properly support delayed ACK.

I can't remember exactly what happens, but if there is a network colision, or some other issue on the network, the client is supposed to send an ACK to the 'server' and wait for a response. The server on receiving the ACK is supposed to wait a specific amount of time, then answer the ACK.

The buggy drivers overlook the fact that the response to the ACK is supposed to be delayed. So upon not receiving the response they immediately send another ACK.

A 'server' working according to specifications (i.e. Mac OS X or any Samba server) is supposed to increase the amount of delay before responding when it receives multiple ACKs, as that is a sign of network congestion and it is trying to allow the congestion to clear up a bit before sending data.

This process can make a 100Mb network run at less than 1MB/s transfer rate. I have experienced this with Netgear FA312 chipset ethernet cards in Pentium IV machines.

In your /etc/smb.conf file there are some GLOBAL settings you can use to fix this:

socket options = TCP_NODELAY IPTOS_LOWDELAY
These tell the Samba daemon to immediately respond to any ACKs received. This technically makes you out of true spec for IP, but it does significantly speed things up when you have one of the cards afflicted by this issue.

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Speed up network between OS X and Windows XP
Authored by: doneitner on Mar 14, '05 10:35:33PM

I actually have a slightly backward version of this problem between OSX 10.3.8 and WinXP over a 100Mbps network. If I initiate a file transfer from the OSX box to copy a file from the WinXP box, I get decent speed (about 9MB/s). If I initiate the same file transfer (Win-to-Mac) from the WinXP box, I get pitifully slow rates.

I just assumed it was yet another further different MS tactic -- to convince users to not move their files off their PCs by throttling the network to non-Windows systems. It certainly wouldn't be the first time they'd done something like that. The fact that i get much better rates when initiating the transfer from MacOS would seem to bare this out, but yeah it could be just a bug. ;)



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