The token ring has several advantages over other networks, especially under a heavy load. However, Bux and Grillo showed that all desirable characteristics of IEEE 802.2 and 802.5 protocols for a single token ring are severely degraded in an interconnected token ring network. In order to address the problem, Bux and Grillo suggested a method of dynamically adjusting the size of windows depending on the traffic of a network. In this thesis, a different method of addressing the problem was proposed. The proposed method is to add a secondary transmission link to the backbone ring of a network to form a double linked backbone ring network. Simulation results show that the most influential element contributing to the degradation of performance is congestion at the bridges in a network. The processing speed of bridges for the proposed double linked backbone ring network is essentially double that of the original network. The increased processing speed of the bridges enhances the performance of the network. Experimental results for the utilization, throughput and response time of the original network and the proposed double linked backbone ring are presented: / Master of Science

Ring networks are appropriate for the full range of network levels, including multiprocessor systems, local area computer networks and high speed backbones. The most well known and widely implemented examples are the IBM token ring and FDDI networks. Ring networks have the advantages of high channel utilisation and bounded delay if an n-limited service policy is used. The packet transfer delay, defined as the average time a packet spends in the network from the time it is generated until the time it is received at its destination node, improves with the number of rings on which a node is connected. However, many ring connections are not economically feasible since the cost of the ring interface increases with the number of rings. There has been an abundance of previous work on single token ring networks. A number of papers on slotted rings, register insertion rings and more complex ring architectures have also been published. However, there is very little existing literature on multiple ring networks as well as ring networks in clustered traffic environments, i.e. where nodes from the same cluster tend to communicate more with each other than with other nodes in the network. This thesis focuses on two network topologies that make use of multiple rings and are well suited to clustered traffic environments: the two-connected multiple ring (2-MR) and the destination removal double ring (DRDR). For the 2-MR network, three different practical token-based protocols are investigated in an attempt to optimise performance. It is further shown that significant performance improvements can be achieved by employing a slotted ring protocol rather than the token ring protocol. The DRDR network is also examined and its performance compared to the aforementioned architectures. For each of the six cases, both random and clustered traffic patterns are considered and compared. Analytical results are derived which are verified by results obtained from computer simulations. Furthermore, we look at exact methods of analysing ring networks. A mean value analysis of a single token ring network with a I-limited service discipline is performed, which clearly shows the complexity exact methods introduce. Finally, although it has been stated in the literature that an exact analysis of a multiple symmetrical token ring network is intractable, we present a novel Markov chain approach that gives exact results for near zero loads. / Thesis (M.Sc.-Electronic Engineering)-University of Natal, 1998.

Thesis (M. App. Sc.)--Carleton University, 2005. / Includes bibliographical references (p. 71-76). Also available in electronic format on the Internet.

Thesis (MTech(Electrical Engineering))--Cape Peninsula University of Technology, 2011 / In a situation, where there is a shortage of power generation or the power stations are operating with a very low reserve margin, as is typically the current position in South Africa, there is a need to operate distribution network at the highest possible efficiency by utilising network power loss reduction techniques. Such techniques are especially important when contingencies occur as they tend to increase loss, reduce efficiencies and cause power supplies to such networks to increase. This increase can cause the network or multiples of such networks to be load shed as the power stations do not have the reserve margins to meet this increased demand. The ideal situation would thus be to minimise network loss and in so doing decrease the amount of power needed and possibly avoid load shedding. Thus, there is a need to study efficiency, network loss reduction under contingency conditions and this is the focus of the research. Most large urban distribution networks are operated as ring main networks. Ring networks are considered to have less power loss. However, a major component in a ring network can cause the loss to substantially increase; resulting in power shortage in the network. There is an urgency to eliminate high network loss. An efficiency plan was developed for a large ring network that reduces the loss so that its input power can be decreased. In this way, the available power existing due to the contingency can be more evenly spread, and the number of ring main networks to be load shed could be reduced.

Thesis (M.App.Sc.) - Carleton University, 2002. / Includes bibliographical references (p. 59-63). Also available in electronic format on the Internet.