Windows Vista/W7 - workaround for problems with download speed by MS

If you use Windows Vista SP1/2, Windows 7 or Windows 2008 and experience problems with fluctuating download speed, significant speed slowdowns, delayed TCP ACK sending resulting in the remote part not sending data or re-sending the same date repeatedly after installing ESET Smart Security, Microsoft acknowledged a bug in the TCP/IP Stack's ACKing logic that can be worked around by setting the registry value TcpAckFrequency to 1 (for complete instructions, read here).

 

Re: MS suggests workaround for problems with 1 GB networks

Why does that KB article refer to XP/2003 and have a date from 2007 on it? Maybe I missed it but I'm not seeing anything related to Windows 7 and 2008?

 

Re: MS suggests workaround for problems with 1 GB networks

Probably because by default the registry entry doesn't exist in 7/2008. Here's a tool that does it for you automatically. Used it for years.

 

Re: MS suggests workaround for problems with 1 GB networks

Should everyone with a Windows 7 / ESS combo use this fix? Or is this problem only present on certain configurations?

 

Re: MS suggests workaround for problems with 1 GB networks

A quote by a MS engineer on the MSDN forum: We've had a root cause of this issue -- The TCP/IP Stack's ACKing logic has a bug when data segments are taken out of and re-injected back to the same flow at a certain ratio. The bug is easier to manifest when the incoming data rate is very high.

 

Re: MS suggests workaround for problems with 1 GB networks

Hello

Does anybody know if this bug is fixed in Windows 7 Service Pack 1?

Thanks in advance

Kevin

 

Re: MS suggests workaround for problems with 1 GB networks

Probably not. SP1 is (very close to) RTM status so I imagine this one will be a seperate bugfix.

Thanks Marcos, I'll apply this fix as a precaution.

EDIT: KB Article about this was created: http://kb.eset.com/esetkb/index?page=content&id=SOLN2654

EDIT2: Perhaps a coincidence, but:

* Before applying fix, download speed was around 117 Mbit (Connection max is 120)
* After applying fix and rebooting, download speed was around 90 Mbit.
* After removing fix and rebooting, download speed was 120 Mbit again.

Can someone with a fast connection confirm or deny this?

 

Re: MS suggests workaround for problems with 1 GB networks

* with fix : 16.5 Mbps
* no fix : 23.6 Mbps

Repeated with very similar results.

 

Re: MS suggests workaround for problems with 1 GB networks

This reg fix means your PC will respond to every pack, rather than every 2 or 4 as it would normally. So you are increasing the overhead by responding to every packet. This means that your download speed will be slightly lower, but latency and response are better.

 

Re: MS suggests workaround for problems with 1 GB networks

Thanks elapsed,
That little vbs took away any guesswork.