Generally speaking, the changes in networking code for 11.0 (from 10.20) will yield significant increases in speed, so the perceived decrease is not normal. You need to establish a baseline (if possible).
Otherwise, I would use lanadmin -x to walk through all your LAN connections and check for full speed (ie, 100 mbit, full duplex) from the driver's point of view. And when auto-negotiation is turned off, it is imperative that the switch be explicitly set to the same value as your LAN card. Otherwise, the switch may be at half duplex and throughput will not be good at all.
Once the LAN speed and duplex are stable, use ftp to transfer a large file, perhaps 100-500 megs and time the result going one way and then the other way and finally two copies going opposite directions, running at the same time. Repeat about 3-5 times and look at the average.
NOTE: This assumes that the other end is properly setup and capable of maintaining maximum thruput most of the time. Now compare the equivalent data rate. The reason to use ftp is the link-aware nature of ftp...it will create packets as fast as the link allows and backoff as necessary when the data rate is too slow, soemthign that NFS or rcp just won't do. And ftp has much lower overhead associated with packet acknowledgement.
Bill Hassell, sysadmin
