A high speed access mechanism for a multiservice LAN at 144 Mbps

The design and implementation of a high-speed access control mechanism for a multiservice LAN (local area network) with a transmission medium speed of 140 Mb/s is presented. The implementation uses discrete components of the fast TTL (transistor-transistor logic) family because the operational speed of the system is 18 Mbytes/s. The experimental results show that the required time for a delimiter event recognition by the hybrid frame is 30 ns, which is well within the byte duration of 56 ns for a duty cycle of 66% and a data rated of 144 Mb/s. The control mechanism also provides continuous monitoring of the downstream activity of the network, providing alarm signals for abnormal situations. The system is totally independent of the structure of the packet and stream data as far as the processing of the communication protocols is concerned and implements the medium-access-control-layer functions in conformance with the ISO model for OSI. This hardware implementation is low in cost and the architecture of the system is well suited to an advanced technology implementation