The goal of traffic engineering is to facilitate efficient and reliable network operation and at the same time optimize the utilization of network resources. Multi-path routing and load balancing among multiple paths are two mechanisms used for traffic engineering. From the other point of view the increase of customers’ requirements, requires the network operators to provide more variety of service classes with end-to-end guaranteed quality of service. Therefore finding a mechanism which is able to provide a high end-to-end service granularity is essential. Such a mechanism can lead to prompt creation of the next generation network. Among all quality of service mechanisms, DiffServ architecture with the help of a call admission control algorithm provides a variety of end-to-end service classes that does not suffer from scalability problem. In this thesis by combining a proper end-point admission control algorithm with a new load balancing mechanism among multiple paths, better network utilization and higher network throughput is achieved. Also by reducing hot spots of the network, lower end-to-end delay was obtained compared to single path routing. The applied call admission control mechanism consists of two phases: probing phase and data transfer phase. The advantage of proposed load balancing algorithm is to use information which is gathered by routers along the path in the probing phase. MPA is used as the multipath routing protocol to find available multiple paths in the network. In the probing phase, each user sends one probing packet into each path to gather required information for both admission control decision and load balancing algorithm. As probing packets pass the routers, each router considers its classes of service and will report the available class of service in probing packets even if it is lower than the requested service class and service vectors will be performed. QoS degradation in each of routers along the path is acceptable since it may not affect the end-to-end QoS or users prefer to have QoS degradation than being blocked. So the decision of load balancing is made with respect to network congestion. By using the buffer length of the routers as a load balancing criteria a good estimation of end-to-end delay and packet loss probability is obtained. The result is a proper load balancing according to network resources in every path. Additionally end-to-end delay was used as a quality of service parameter to choose proper paths at the destination. The proposed network was implemented in OPNET. Simulation results show the improvement which is made by the proposed algorithm in the area of traffic engineering. Keywords Multi-Path Routing, Load Balancing, End-point Admission Control, QoS