A multiple-session medium access control protocol for a ring topology local area network
Kam Chuen Lau · 1995
One potential disadvantage of contemporary local area network (LAN) designs is that only a single communication can be in progress in the network at any one time. The primary reason for this limitation is to avoid transmission medium contention. Conventional parallel transmission protocols such as the fiber distributed data interface (FDDI) protocol and the slotted ring protocol support a limited degree of concurrent transmission, and they may only be effective when the signal propagation delay around the network is relatively long, i.e., high data transfer rate and large network size. In contrast, the proposed multiple-session medium access control (MAC) protocol can create more than one communication path simultaneously among the entities in a ring topology network regardless of the transmission speed and the network size. The number of communications that can take place concurrently is limited only by the availability of the transmission medium. Thus, for an N-entity network, a potential N/2-fold improvement in the overall system throughput is obtainable (assuming that an entity can either transmit or receive but not do both at the same time). Furthermore, since the communication channel requests are initiated asynchronously, a shorter transmission delay can be expected compared to the token passing MAC protocol. However, a non-regulated random channel initiation request may result in a deadlock occurrence. To ensure a deadlock-free network operation, a technique used to avoid deadlock in the wormhole routing algorithm is applied. The hypothesis of this research was that the multiple-session medium access control (MSMAC) protocol could improve the network performance over a sequential medium access control protocol (e.g., token passing) under certain conditions. The objectives of this research were to design such a deadlock-free concurrent transmission MAC protocol, and to verify and investigate its effectiveness under various conditions through computer simulations. The simulations were performed by using the Block Oriented Network Simulator (BONeS) System. The details of designing the MSMAC protocol and its simulations are presented in this thesis. The performance characteristics of the protocol are inferred from the simulation results. The performance gained by employing the MSMAC protocol instead of the conventional ones is optimized by high locality, long transmission length, heavy traffic intensity and large network size. Since the degree of medium contention in a client-server network configuration is less than in a peer-to-peer network environment, consequently, higher degree of concurrent transmissions is expected. The MSMAC protocol will be more effective in a client-server network application than in a peer-to-peer network model.