Quote:
Originally Posted by injuneer
I installed this on Wednesday with no problem. However I have since noticed that my ADSL download speeds have dropped to 10% of what they previously were! (usually around 3 MB/s but now 300 KB/s & only about 10KB/s when downloading email!) Upload speeds were unaltered at about 1MB/s.
I was going to complain to O2 but then thought I'd drop back to SP2 just in case, low & behold everything is back to normal. Has anybody else experienced this? I was wondering if it was a USB2 issue as I use a Thomson Wireless adapter in a USB2 port. I have read about people having data transfer speed problems when using external hard drives after loading SP3.
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Could be tcp blackhole detection.
If you want to try SP3 again after installing it do this.
Open regedit.
goto
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Servic es\Tcpip\Parameters
Look for EnablePMTUBHDetect
XP pre SP3 defaults to 0 (disabled)
Vista and XP SP3 default to 1 (enabled).
I have mine on and have noticed no significant impact but this is what it does.
Normally mtu discovery uses icmp packets to determine optimal mtu size on route, but some server admins and isps block all icmp traffic which breaks pmtu discovery. Microsoft developed a workaround with this which checks mss sizes (i think) until it sees a fragment which then finds the optimal size. I am using it but I can see it could slow things down at the start of downloads as it is doing more to determine the optimal mss/mtu size.
---------- Post added at 02:34 ---------- Previous post was at 02:33 ----------
no space in Services not sure why the forum is inserting a space.