| 摘要 |
A traffic load control arrangement for a packet switching system (FIGS. 1A and 1B) uses a circuit (1521) in each trunk controller (131) to determine the call traffic load of the trunk controller. To set up a call path, the central processor (115) of a switch (102) selects a trunk (118) to serve the call and sends a logical channel setup packet (500e) indicating either forced or normal selection to the selected trunk's controller (131). If normal selection is indicated, the selected trunk controller refuses to serve the call and returns a channel setup no-acknowledgement packet (500f) to the central processor if the trunk controller's load exceeds a predetermined level. Otherwise, the trunk controller sets up a channel to serve the call and returns a channel setup acknowledgment packet (500g) to the central processor. In response to the no-acknowledgment packet, the central processor attempts to find another trunk to serve the call. In the case of a toll office (104), if no other trunk can be found and a call setup acknowledgment packet (500n) has not yet been returned by the toll office switch to the preceding switch, the toll office switch returns a call setup no-acknowledgment packet (500o) to the preceding switch. The preceding switch responds to receipt of the no-acknowledgment packet by attempting to find a trunk leading to another switch to serve the call.
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