Long Messages fragment over network
 

I have a RHEL 4 server delivering long messages to several RHEL 4 clients. They work fine. I am trying a RHEL 5 client running the same client application as the RHEL 4 clients. The RHEL 5 client looses most messages. I have tried with two other clients running CentOS 5 with similar results. The server indicates write failure or blocked. The messages are typically 50 kilobytes. I have changed many parameters in sysctl.conf . Has anyone encountered similar problems? Any solutions?
Thanks,
Jim Cole

what's the transport? A TCP/IP socket? A UDP socket? An HTTP web service? Something else entirely?

What log files have you looked at? Are there any application level logs which might also provide useful clues?

I would *not* fiddle with kernel parameters except as a last resort. Certainly not before we have a better idea about "what's wrong".

IMHO .. PSM

This is TCP over a socket connection.
The application is written specifically to receive and
pass on messages from a remote server. I have a reasonable
amount of networking experience and have configured sysctl.conf
for a variety of purposes. The internal logs report
the error code for every failed write. The error codes
at the server indicate write fail or write blocked.
Thanks for your response.
Jim Cole

It appears that we have solved the problem.
We have run since 10/25 00:35 EDT with no failures.
We added setsockopt SO_RCVBUF 8000000
setsockopt SO_SNDBUF 1000000
We added to sysctl.conf large maximums of 16777216
for net.ipv4.tcp_rmem net.ipv4.tcp_wmem
net.ipv4.tcp_mem
net.core.rmem_max net.core.wmem_max
Jim Cole