Network performance issues are rather beyond the scope of this forum:
you'd be better off conferring with your networking people, who can
evaluate what you're attempting and run traces to see what's actually
happening.

When approaching network performance test like this, the big affector
is network topology. In this case, I would expect that the two systems
being tested were in different subnets, going across one or more
routers, where the jumbo frames may have had to be disassembled into
smaller pieces, which incurs overhead. Again, this is something your
site network people have to look at.

   Richard Sims

On Mar 23, 2005, at 12:04 PM, Miller, Ryan wrote:

Here's a question from one of my cohorts, since this is our first try
at this, I thought I would see if I could get any input from anyone
else doing this.

We have been testing jumbo frames(8990) using TSM on an AIX client.
The base line test with MTU of 1500 moved 22G in 44 minutes. Changing
the MTU to 8990 and the TCP receive and send buffer sizes on both the
mainframe and AIX client to 256K, the same 22G of data takes 1 hour
and 40 minutes.

Also the largest input packet size is 8192, not 8940. Are their any
tcp parameters to se on the client that would help with the jumbo
frame transfer time?