tcp window size + linux
652808Jul 30 2008 — edited Jul 31 2008I am having some problems with TCP window size on my linux boxes. No matter what settings I use for tcp_rmem/tcp_wmem rmem_max/wmem/max, the TCP window for a file transfer always stays at 5820 bytes.
The tcpdump (checking for ACK bit ) confirms that the window size is ~5k with a scaling factor of 8 (2^8=256). On subsequent transfers, the window size drops to 23. (23*256=5888) sounds like the correct size of window, although never exceeds the 5888 bytes value.
I have tried ridiculously large values (16M) for tcp_rmem/wmem, however not been able to change that window size of 5820. Is there a way to make this window size 64k with scaling of 256?
I am using the following values for TCP windows:
net/core/rmem_max = 8738000
net/core/wmem_max = 6553600
net/ipv4/tcp_rmem = 8192 873800 8738000
net/ipv4/tcp_wmem = 4096 655360 6553600
(as per this website: http://www.acc.umu.se/~maswan/linux-netperf.txt)
both servers are OEL4U4 with near identical hardware.