An investigation of CCS tandem overload control issues

In this paper we analyze issues associated with overloads in tandem switching systems in common channel signaling (CCS) networks. In particular, we examine the need for, and effectiveness of, automatic congestion control (ACC), a CCS mechanism which allows switching systems to inform originating exchanges of overloaded processing resources and thereby control call rates to congested nodes. We demonstrate the critical need for end-offices and tandem switching systems to implement some form of ACC if network performance is to be maintained during congestion in tandem exchanges. In addition, we find that the presently defined ACC should be expanded to allow more levels of congestion to be reported to originating nodes, so that a more effective, finer grained control is produced