How to enable 'tcp window scaling' on HP-UX?

[MA Qiang]

On Linux, we can use 'echo 1 > /proc/sys/net/ipv4/tcp_window_scaling' to enable it.

Thanks.

[LiPEnS · Accepted solution]

Hi
RFC 1323 support is enabled automagically in HP-UX 11. If an application requests a window/socket buffer size greater than 64 KB, window scaling and timestamps will be used automatically.

The default TCP window size in HP-UX 11 remains 32768 bytes and can be altered though ndd and the settings:

tcp_recv_hiwater_def
tcp_recv_hiwater_lfp
tcp_recv_hiwater_lnp
tcp_xmit_hiwater_def
tcp_xmit_hiwater_lfp
tcp_xmit_hiwater_lnp

All supported TCP parameters in HP-UX and ndd tuning describe ftp://ftp.cup.hp.com/dist/networking/briefs/annotated_ndd.txt

[Zeev Schultz]

ndd -h | grep window

Pick the parameter you need.I guess that will be tcp_recv_hiwater_def.Usually advised to set window size on application basis using setsockopt() SO_RCVBUF. I also think that its upper limit is 64k , while in Linux tcp_window_scaling is set for those larger than 64k...

Anyway, you set the parameter with ndd,
to preserve on boot add it ot /etc/rc.config.d/nddconf