Adjust LANs for optimum communications performance
Local area networks (LAN) affect the communications performance on the iSeries™ server. Improvements to LAN input/output (IOPs) in the areas of increased
central processing unit (CPU) time, IOP capacity, and support of IOP assist
make them more efficient. This efficiency allows advanced program-to-program
communications (APPC) to send request units to the IOP, passing the cost of
processing frames to the IOP.
The following information can help you understand the protocol considerations
for local area networks.
- A Data Link Control (DLC) can achieve a significantly higher data rate
than other supported line types. This is due to the desirable combination
of having a high media speed along with large frame sizes.
- When several sessions use a line or LAN concurrently, the aggregate data
rate might be higher than when only one session is used.
- To achieve good performance in a multi-user interactive LAN environment,
you should manage the number of active users so that LAN media use does not
exceed 50%. (A 25% utilization is recommended for Ethernet environments because
of media collisions that causes the program to loop). Operating at higher
utilization might decrease response time because of excess queueing time for
the line. In a large transfer environment in which a small number of users
contend for the line, a higher line use might still offer acceptable performance.
For more information about iSeries server configuration, see the Communications Configuration
book.