markp
December 30th 04, 06:42 PM
I had a problem with a slow internet XP system after an SP2 update on my
laptop which was subsequently fixed, this post is for information purposes
for those who may be googling for an answer to their problems!
I use a proxy server to get to the internet, and there is no other way of
accessing the internet from my local network. One of the clients, a WinXP
laptop machine, was upgraded to SP2. The laptop was then very slow at
accessing mail or browsing the internet - sometimes pages would partially
download or not at all, and would take a very long time to do so.
The first thing I did was a netstat from the command prompt on the client,
and found that there were several half open connections to internet
addresses being created. Netstat also took some time to complete. I googled
and found that SP2 limits simultaneous half open connections to 10 before
throttling further requests, this is not a registry setting but hard coded
into the TCPIP.SYS file. The idea is to stop the spread of worms and the
like (and conspiracy theories abound about P2P programs being throttled
abound), but without limiting legitimate accesses.
Since netstat was slow to complete and showed half open connections actually
in the process of being created, I thought that there could be applications
on the laptop requesting internet access, and the 10 limit was exceeded
thereby throttling further accesses. This was confirmed by a look at the
system event log (right click on My Computer -> Manage -> Event Viewer ->
System) which showed a yellow warning triangle with a new Event ID 4266:
TCP/IP has reached the security limit imposed on the number of concurrent
TCP connect attempts.
So I installed ZoneAlarm (www.zonealarm.com) to catch whichever applications
were doing this and block them. I had things like Skype and other apps all
trying to find updates all at once. Since these were on the local network
they were all half open requests which could never complete. By blocking
these the 4266 error disappeared. Also I increased the limit of simultaneous
half open connections to 50 using this little utility:
http://www.lvllord.de/?lang=en&url=tools
After all that my SP2 udated laptop is running very smoothly with fast
internet access.
HTH!
Mark.
laptop which was subsequently fixed, this post is for information purposes
for those who may be googling for an answer to their problems!
I use a proxy server to get to the internet, and there is no other way of
accessing the internet from my local network. One of the clients, a WinXP
laptop machine, was upgraded to SP2. The laptop was then very slow at
accessing mail or browsing the internet - sometimes pages would partially
download or not at all, and would take a very long time to do so.
The first thing I did was a netstat from the command prompt on the client,
and found that there were several half open connections to internet
addresses being created. Netstat also took some time to complete. I googled
and found that SP2 limits simultaneous half open connections to 10 before
throttling further requests, this is not a registry setting but hard coded
into the TCPIP.SYS file. The idea is to stop the spread of worms and the
like (and conspiracy theories abound about P2P programs being throttled
abound), but without limiting legitimate accesses.
Since netstat was slow to complete and showed half open connections actually
in the process of being created, I thought that there could be applications
on the laptop requesting internet access, and the 10 limit was exceeded
thereby throttling further accesses. This was confirmed by a look at the
system event log (right click on My Computer -> Manage -> Event Viewer ->
System) which showed a yellow warning triangle with a new Event ID 4266:
TCP/IP has reached the security limit imposed on the number of concurrent
TCP connect attempts.
So I installed ZoneAlarm (www.zonealarm.com) to catch whichever applications
were doing this and block them. I had things like Skype and other apps all
trying to find updates all at once. Since these were on the local network
they were all half open requests which could never complete. By blocking
these the 4266 error disappeared. Also I increased the limit of simultaneous
half open connections to 50 using this little utility:
http://www.lvllord.de/?lang=en&url=tools
After all that my SP2 udated laptop is running very smoothly with fast
internet access.
HTH!
Mark.