Research On The Bandwidth Allocation In Modern Communication Network

The Internet, which is a huge and growing public network of linked computers and information, is changing the way we study, shop, share our culture and communicate with our friends and family. However,in modern communications network, in order to utilize precious bandwidth resource efficiently, static allocation policies, which usually distribute bandwidth in advance, can not meet the demand of fast-growing communications. Dynamic allocation policies, which are based on fluctuations in traffic, have now become the focus of researches.In traditional ATM networks, the most widely used dynamic bandwidth allocation algorithm is known as"Bisection Algorithm". A newly presented"Step Algorithm"possesses its advantage in allocation time over the previous one. However, recurrent Kaufman formula used to compute call blocking probabilities (CBPs) of virtual paths in"Step Algorithm"is time-consuming. Alternatively, too much time in dynamic allocation is spent on computing call blocking probabilities. In this paper, a fast approximate algorithm, which is based on quasi-independent and used to compute CBPs is generalized to the case of preserving bandwidth to replace Kaufman formula. Also, one step in"Step Algorithm", which takes off one unit of bandwidth away from the virtual path with lowest CBP in the whole network, is explained to be immoderate. And it is amended to be as subtracting one unit from the virtual path with lowest CBP in constrained links. Simulation results indicate that the speed of"Step Algorithm"is greatly increased which benefits from the two modifications. In addition, in reference document, a mathematic justification verifying the optimality of"Step Algorithm"is proposed. However, it seems a bit complex. In this dissertation, a simple deduction is given, which verifies the optimality of"Step Algorithm".The process of analyzing"Step Algorithm"gives us food for thought. That is, whether equal increase or decrease in the bandwidth of two virtual paths will result in rearrangement of the sequence of CBPs of these two. In this paper, a conclusion is drawn by reasoning and also confirmed by simulation.MPLS is a newly-emerging network absorbing merits both from IP network and ATM network. For the purpose of guaranteeing an expensive so-called"premium service"which is usually used by voice and video transmission, a new conception known as"pipe"is brought forward. At the same time, a threshold-based prediction...