James,
First, you have determined that the large packet size is working between
the two systems. What appears to be happening on the SLES9 is that once
you trigger the ICMP packet too large response, the TCP/IP stack is
dynamically lowering the reported MTU to 32000. Once communication with
a s
I went and ran the ping test to see how SLES8 vs SLES9 would behave given the
tracepath differences I've found.
Some background to just refresh:
Hipersocket interface is set to 64 K on the CHPID. There is 8K of overhead so
the MTU is really 57344, and that is what the interface sets itself to
at
How PMTU Discovery works in the network:
Path MTU Discovery depends upon two IP capabilities. IP packets sent
will have the "do-not-fragment" option set in the IP header. When an
outbound interface in the path is encountered that can not transmit
the packet because its MTU is less tha
We've been seeing some disturbing differences between the packet size being
(aparrently) sent on SLES9 vs SLES8 over the hipersocket interface.
The tool we have been using to tell us the packet length going over the
hipersocket is tracepath.
On SLES8:
nokomis:~ # uname -r
2.4.21-83-default
nok
