Research On Recovery Scheme Of MPLS-Based Network

Multiprotocol Label Switching (MPLS) is the key technology of backbone IP network, with good prospect. In MPLS network, forwarding of IP packet is driven by the fixed-length labels. Compared with conventional IP forwarding, MPLS has more flexible control and management for the traffic service. As the key switch technology of backbone network, MPLS has to response as fast as possible, otherwise, it will result in degradation of QoS level.IETF(Internet Engineering Task force)divides the MPLS-based recovery into two models:. reroute and protection switching(fast rerouting). Recovery by rerouting model is defined as establishing new paths on demand for restoring traffic after the occurrence of a fault. But protection switching mechanism need pre-establish a recovery path or path segment to switch working traffic. That is the just chief difference between the two models. The thesis expatiates the research aiming at the two models respectively, and the central achievements is shown as follows:Under the Diff-Serv environment, this thesis described an algorithm for rerouting which is based on Multi-failures model and centralized implementation model. Dividing the LSPs according to the set-up priority and holding priority of LSP, the algorithm focuses on the bandwidth requirements for each LSPs in order to meet the different QoS requirements of LSPs. Furthermore, it is carried out by a optimization equation based constraint route of MPLS TE. after the occurrence of failure, LSPs with high-priority will possess the network resource with precedence, as well as preempt the LSPs with low-priority while there is lack of network resource .It can ensure the QoS level of the critical service traffic. At last, the case study has validated the feasibility and the advantage.In the case of that backup path has been pre-established, a scheme named EB for MPLS-based recovery is present, which introduces the modified Backpressure signaling mechanism to Bridge model in order to eliminate the packet disordering. In addition, combining the two existed classical scheme (Haskin, Makam), the thesis launch both theoretical analyses and simulation experiment to prove out the recovery performance. General indicating, EB not only preserves advantages of Bridge but also solves the packet disordering. Comprehensively evaluating, comparing with existed scheme, better performance is shown by EB.Besides, the thesis proposes an enhanced scheme based QoS protection, which adopts a hybrid approach of segment protection and path protection. In detail, Introducing the combination way of Haskin and Makam, locally returning in SPD(Segment Protection Domain)is implemented in order to minimize the restoration time of Haskin and Makam, as well as the average delay of existed scheme Local Reverse. Meanwhile, the evaluating function of QoS protection for MPLS recovery is enhanced to evaluate Haskin, Makam, Local Reverse, and proposed model. The experiment results indicate that better performance is shown by the proposal. The experiment results that better performance is kept up by the proposal, for the four different traffic classes under Diff-Serv.