[Info-vax] OT: TCP: trading latency for bandwidth

[JF Mezei]

someone wrote:
>> By deficiencies, are you referring to the slow performance?  I've always found the TCP/IP stacks on VMS to be incredibly sluggish.  It's not just a bandwidth problem, it's very slow (relatively speaking) at reading and sending very small packets.  The situation on a platform like Linux is quite different.  It's very tragic.


At one point, I thought I was having IP performance problems on the link
and was using FTP as a means to check upload and download speeds (since
VMS doesn't have a working  flash which is used for most speed tests).

ftp tests showed poor performance.

I did the same tests on my xserve (OS-X) and low and behold, the
performance difference was very drastic and make full use of the line
speed  (showing the line had no problems).

I had already set a large TCPIP$FTP_WINDOW_SIZE (if I recall correctly)
and it didn't seem to make a difference.

There may be some paarmeters that can be set in TCPIP$ETC file
(systemconfig or something akin to this), but out of the box, the
performance was significantly lower than on OS-X (which came from freeBSD)

It is also possible that the FTP application was not properly ported and
fails to use any performance enhnacements possible on VMS.

The end result is that the peformance was sigificantly slower on VMS
than on OS-X.