COMMUNICATION SYSTEM, CONGESTION AVOIDANCE METHOD, AND GATEWAY

摘要

PROBLEM TO BE SOLVED: To prevent a system from falling into congestion by keeping an existing call, when a device for policy control or charge control fails or falls into congestion.SOLUTION: An EPC gateway (SGW/PGW) keeps an existing call associated with a PCRF/DRA when a failure or congestion occurs in the PCRF/DRA; and permits a call connection request by automatically performing, in a call unit, switching of a PCC cooperation mode or a PCC non-cooperation mode. A PCC rule acquisition failure is not notified of even when the PCRF receives a PCC rule acquisition request from only one of the SGW/PGW. After recovery from the failure or congestion in the PCRF/DRA, a call whose connection is permitted in the PCC non-cooperation mode is disconnected by being led by the SGW/PGW to expedite restoration into the PCC cooperation mode. An EPC monitoring device is used for automatically switching the PCC cooperation mode and PCC non-cooperation mode.