The service specific connection oriented protocol is now being studied for use as the ATM adaptation layer protocol for connection oriented data communication and UNI/NNI signaling in the B-ISDN. The key feature of this protocol is a numbered poll mechanism that enables status information to be exchanged frequently and that is helpful for selective retransmission for frame loss. This paper examines this mechanism from the viewpoints of polling interval and frame length. Because this protocol was designed to perform selective retransmission for error recovery, some requirements, such as saving buffer, are not met. Two enhancements are therefore proposed: one consists of a Go-back-N-like procedure and nonassured credit, and the other is an SD PDU with a P bit. Guidelines to determine the POLL PDU interval are given.>

A protocol control system architecture that provides very high processing performance for gigabit-per-second data communication in a broadband network is described. The architecture connects protocol controllers in parallel and uses a distributed multilink method that features a distributed algorithm for allocating transmission on the transmitting side and a resequencing algorithm on the receiving side. The system performance and the influence of transmission errors caused by cell loss in an asynchronous transfer mode network are evaluated. It is shown that by reducing each controller's distributing overhead, the system increases throughput up to 90 times that achieved when using a single controller.>