Mesh Wdm Network Based On The Availability Of Connections

WITH the explosive increase in network traffic and the emergence of high performance optical network devices, such as optical cross-connect (OXC) and optical add/drop multiplexer (OADM), Wavelength Division Multiplexing (WDM) technology becomes the core technology of next generation backbone networks. WDM technology provides the tremendous bandwidth, while poses the survivability issue urgent. In WDM network, the failure of a network component can lead to tremendous loss than in other traditional networks. For example, a failed fiber link can lead to the failure of all the lightpaths that traverse the failed link, since each lightpath is expected to operate at a rate of several gigabytes per second, a failure can lead to a severe data loss. Research on the survivability in WDM networks has huge application value.At the same time, the requirements of network availability of different applications can be quite different too. Some applications, such as e-commerce and the inter-bank clearing operations, have very high requirements on network availability, and need the transmission to be very reliable, and are willing to pay more fees for high-quality services. Some other applications, such as the WWW service, FTP services, EMAIL services, etc, have much lower requirements on available quality of service. It is one of the trends in optical networks to provide users with services of differentiated availability. In the current context of diversification of services, how to provide users with services of differentiated availability while making the best use of network resources at the same time become the focus in research in recent years.This thesis focuses on the availability issues in WDM mesh networks, including the computation of connection availability, dynamic provisioning with availability guarantee, etc.In chapter 2, we propose two methods estimating connection availability against the disadvantages in previous references on availability computation with shared protection. The first method solves the connection availability computation where the fixed wavelength sharing technique is applied. We employ a simplified continues-time Markov chain and arrive at the analytic expression for connection availability by solving the steady-state probability. And we verify the accuracy of the method by solving its threshold. The second method solves the connection availability computation where the link vector technique is applied. We bring up an idea to solve the problem, and give a heuristic formula.In chapter 3, we analyze the dynamic provisioning with availability guarantee. We do the research and propose several algorithms for the provisioning separately according to whether the network has the ability of full wavelength-conversion. We apply the methods proposed in chapter 2 for availability computation in the algorithms. The research is aimed at making best use of the network resources for dynamic connection requests considering wavelength continuity and connection availability constraint.In chapter 4, we implement the simulation for one provisioning algorithm in last chapter where the network has the ability of full wavelength-conversion. Verification is done for this algorithm. And this algorithm can be used to do the routing and resource allocation for the connection requests with availability constraints in NSF network.