Interconnection of token rings by IEEE 802.6 metropolitan area networks

A performance study is presented of the proposed IEEE 802.6 standard (DQDB MAN) used as a backbone loop network in packet-switching mode to interconnect token rings that operate as specified in the ANSI/IEEE 802.5 standard. Interconnection between DQDB and token rings is provided by gateways that use assembly and segmentation processors and limited buffer sizes. The authors consider a network architecture in which Type 2 of the IEEE 802.2 logical-link-control (LLC) standard is used as end-to-end protocol between stations on the token rings. The use of the former and current DQDB slot formats are compared. Several window sizes, different policy schemes, and various traffic intensities and bit rates in token rings are also considered. Using the current DQDB slot size, results show that higher access priority should be allocated to the gateways in the token rings and also show the importance of reducing the time caused by the segmentation of packets in the gateways