Fault recovery in data networks

The purpose of the bachelor’s thesis was to explain the basic principles and technologies for ensuring reliable and effective routing within networks when a link failure. This is with minimal effect to the quality of service. The focus was on mechanisms ensuring the quality of services within the network, especially differentiated services and the both groups of dynamic routing protocols – distance vectors and link state protocols. On the basis of obtained knowledge, the simulation has been designed in OPNET Modeler. It simulated routing of routing protocols RIP and OSPF of networks without any failure. The next simulations containted the link failure and the link recovery. Then the network with DiffServ was designed. It filtered data packets according to used ports and protocol and it added a label to packet with a priority for the certain service. The attention in the network was focused on the VoIP service and its parameters, such as jitter and end-to-end delay. It has also monitored the value of dropped traffic. It simulated the networks with the link failure and the link recovery. The results were compared to the network with no QoS and network with QoS but no failure