Global use of information technology and the use of the internet across wide areas of the economy have resulted in world-wide cross-linking and massively increased demands on existing communication networks. Network availability and security must be considered as crucial factors for the entire economy. As a result of this process, this diploma thesis discusses the various options available for constructing networks with sufficient capacity for all foreseeable needs.

Part I describes different redundancy concepts for a rather large, fictitious company network according to the given tasks. The goal was to find different redundancy approaches and to include them in the subsequent work. Each subtask discusses possible solutions, their pros and cons in the form of a short quality assessment, a task that finally leads to the selected decision. Based on this particular solution, the work discusses possible realization strategies and the components needed to solve the task.

Based on part I, the achieved cognitions are verified in a test system. Different tests and analyses are carried out in a small router network, built up with four different routers. By using Cisco?s network operating system IOS, the documentation points out different implementations of redundancy methods. This practical part II is based primarily on the OSPF routing protocol, which is considered to be an emerging but near fail-safe, versatile and well proven protocol. The next step verifies the results of our tests in detail. In addition to the implementation with OSPF an HSRP installation was set up on two routers, in order to analyse the differences to OSPF.

As mentioned above, the dependence of the economy on efficient network connections is considerable. With the application of redundancy in connection with higher availability, the costs have to be taken into account too, as increased security can not be achieved without increased financial outlay.