[Q] congestion window of sender

[Choi Dong Joon]

I am measuring TCP performance with long fat network (e.g.
satellite network) - 540 msec RTT and 155Mbps bandwidth (ATM, CLIP).

9 Mbytes window size for the maximum throughput. 

So I changed the tcp window size defined in the following proc files.

/proc/sys/net/core/rmem_default
/proc/sys/net/core/rmem_max
/proc/sys/net/core/wmem_default
/proc/sys/net/core/rmem_max

I measured ttcp or iperf and analyzed it using tcptrace after tcpdump.

Sometime (usually after reboot) I could get maximum throughput
but many times I could not get reasonable throughput. When I
tcpdump it, analyzed by tcptrace and xplot, the tcp congestion 
window size of sender does not increase even though the advertized 
window by receiver is enough large. 

But after long time without anything, the TCP works normally. 
(I could get the maximum throughput)

What is the problem ? 

I use redhat 7.1 and kernel 2.4.16.