z/OS Communications Server V1R8 SNA Network Implementation Guide
Publication update for z/OS Communications Server V1R8 SNA Network Implementation Guide
Resolving the problem
In Chapter 6. Using Enterprise Extender, in the "Tuning the EE network" section, add a new section after "Enterprise Extender LDLC keep-alive reduction called "Enterprise Extender Improved Packet Loss Tolerance".
Enterprise Extender Improved Packet Loss Tolerance
While RTP pipes generally perform very well over Enterprise Extender under ideal network conditions, the overall performance of RTP pipes may be significantly impacted when packet loss is occurring. The Enterprise Extender improved packet loss tolerance function is designed to improve the performance of RTP pipes while running in non-ideal network conditions. This function is enabled by coding the HPRCLKRT start option to the ADAPTIVE mode.
Coding ADAPTIVE for the HPRCLKRT setting allows the HPR clock to operate in adaptive mode. Running the HPR clock in adaptive mode allows the clock to toggle between standard and high modes of operation when servicing RTP pipes which are experiencing packet loss. When packet loss occurs, the clock speed adapts to run in high mode. This causes more frequent scheduling of the RTP pipes which are experiencing packet loss, allowing the RTP pipes to recover quicker. There may be some CPU overhead for running the HPR clock in high mode. When packet loss is no longer occurring, the clock returns to the standard mode.
The adaptive mode is designed to increase the overall performance of RTP pipes when packet loss is occurring. However, RTP performance and CPU overhead are system dependent and may vary accordingly.
- This mode is only meaningful in Enterprise Extender configurations which have a defined capacity of 1G (gigabit) or higher access speeds.
- This mode is not recommended for uniprocessor configurations or in configurations which are CPU bound.