I have a strange situation regarding a Windows PC which is showing limited internet transfer speeds for no apparent reason. If I am performing the same test on Linux box then I am getting good speed.<\/p>\n
Upon intense debugging, I am able to diagnose and find out the root cause of the problem.<\/p>\n
It was\/is Windows HTTP packet fragmentation that happens locally. Basically its
how windows compile HTTP headers locally so found a fix to it.<\/p>\n
We came across some TCP settings which restrict download speed in the windows
box, hence in order to permit download of large files, have modified below
settings:<\/p>\n
These were my initial TCP settings<\/p>\n
\nC:Windowssystem32>netsh interface tcp show global<\/p>\n
Querying active state…<\/p>\n
TCP Global Parameters<\/p>\n
———————————————-<\/p>\n
Receive-Side Scaling State: disabled<\/p>\n
Chimney Offload State : automatic<\/p>\n
NetDMA State: enabled<\/p>\n
Direct Cache Acess (DCA): disabled<\/p>\n
Receive Window Auto-Tuning Level: disabled<\/p>\n
Add-On Congestion Control Provider: none<\/p>\n
ECN Capability: disabled<\/p>\n
RFC 1323 Timestamps : disabled<\/p>\n
** The above autotuninglevel setting is the result of Windows Scaling heuristics<\/p>\n
overriding any local\/policy configuration on at least one profile.<\/p>\n
C:Windowssystem32>netsh interface tcp show heuristics<\/p>\n
TCP Window Scaling heuristics Parameters<\/p>\n
———————————————-<\/p>\n
Window Scaling heuristics : enabled<\/p>\n
Qualifying Destination Threshold: 3<\/p>\n
Profile type unknown: normal<\/p>\n
Profile type public : normal<\/p>\n
Profile type private: restricted<\/p>\n
Profile type domain : normal<\/p>\n<\/blockquote>\n
Thus I did:<\/p>\n
\n# disable heuristics<\/p>\n
C:Windowssystem32>netsh interface tcp set heuristics wsh=disabled<\/p>\n
Ok.<\/p>\n
# enable receive-side scaling<\/p>\n
C:Windowssystem32>netsh int tcp set global rss=enabled<\/p>\n
Ok.<\/p>\n
# manually set autotuning profile<\/p>\n
C:Windowssystem32>netsh interface tcp set global autotuning=experimental<\/p>\n
Ok.<\/p>\n
# set congestion provider<\/p>\n
C:Windowssystem32>netsh interface tcp set global congestionprovider=ctcp<\/p>\n
Ok.<\/p>\n
C:Windowssystem32>netsh interface tcp show global<\/p>\n
Querying active state…<\/p>\n
TCP Global Parameters<\/p>\n
———————————————-<\/p>\n
Receive-Side Scaling State: enabled<\/p>\n
Chimney Offload State : automatic<\/p>\n
NetDMA State: enabled<\/p>\n
Direct Cache Acess (DCA): disabled<\/p>\n
Receive Window Auto-Tuning Level: experimental<\/p>\n
Add-On Congestion Control Provider: ctcp<\/p>\n
ECN Capability: disabled<\/p>\n
RFC 1323 Timestamps : disabled<\/p>\n<\/blockquote>\n
After changing these settings downloading is fast again, hitting the internet connection’s limit.<\/p>\n