The TUPEVN_CONGESTION event indicates one of the following congestion issues:
Memory usage on the TX board has become very high.
The queue in the TUP service is growing.
In either case, you get a congestion level of 0 through 3 in the value element of the CTA_EVENT structure.
If your application receives a level 1 event, reduce the number of calls being generated. At levels 2 and 3 , avoid all new calls and clear existing calls. As memory usage lowers or the outbound queue shrinks, congestion events with lower congestion levels are generated for the application to resume more normal traffic.
If your application requires additional information about the congestion, call TUPGetApiStats for additional statistics.