ERROR MONITORING ISSUES FOR COMMON CHANNEL SIGNALING

Motivated by field data which showed a large number of link changeover s and incidences of link oscillations between in-service and out-of-se rvice states in common channel signaling (CCS) networks, a number of a nalyses of the link error monitoring procedures in the SS7 protocol we re performed by the authors. This paper summarizes the results obtaine d thus far and include the following: a) results of an exact analysis of the performance of the error monitoring procedures under both rando m and bursty errors; b) a demonstration that there exists a range of e rror rates within which the error monitoring procedures of SS7 may ind uce frequent changeovers and changebacks; c) an analysis of the perfor mance of the SS7 level-2 transmission protocol to determine the tolera ble error rates within which the delay requirements can be met; d) a d emonstration that the tolerable error rate depends strongly on various link and traffic characteristics, thereby implying that a single set of error monitor parameters will not work well in all situations; e) s ome recommendations on a customizable/adaptable scheme of error monito ring with a discussion on their implementability. These issues may be particularly relevant in the presence of anticipated increases in SS7 traffic due to widespread deployment of Advanced Intelligent Network ( AIN) and Personal Communications Service (PCS) as well as for developi ng procedures for high-speed SS7 links currently under consideration b y standards bodies.