A Call-Processing Traffic Study for Integrated Digital Loop Carrier Applications

This paper presents the results of a traffic study undertaken to determine if a 64 kbit/s common signaling channel is sufficiently fast to meet the present and future call-processing needs of integrated digital loop carrier (IDLC) systems. Bell Communications Research (Bellcore) has proposed the use of such a 64 kbit/s common signaling channel in a requirements document, technical reference TR-TSY-000303, to satisfy call-processing needs across the IDLC generic interface, whenever out-of-band signaling is used. This paper characterizes IDLC call-processing traffic on this message-oriented common signaling channel and examines associated design requirements in TR-303 under certain modeling assumptions (Poisson arrivals and exponential service time). Under worst case conditions, the study concluded that a critical message requiring a response within 100 ms would practically always meet that delay criterion. Critical messages requiring a response within 40 ms would fail once every 10 busy hours. Since no specific signaling response requirement of 40 ms has been found, the study concludes that a 64 kbit/s common-signaling-channel for IDLC systems is sufficiently fast to achieve required signaling response times.