Fast Re-routing Based On Mpls Traffic Engineering Tunnel Of Multi-level Study

Due to the increasing complexity of network topology caused by the extensive application of Internet technology, the traditional route search modes based on the destination can easily lead to the imbalance of network load and the reduction of effective resources utilization. With the approach of MPLS (Multi-protocol Label Switching) which combines the high-speed exchange of the second layer and the flexible route search of the third layer, network has had such performance as high-speed exchange, flow control and so on.On the basis of the existing single-layer MPLS-TE, a new model of MPLS-TE, fast reroute on multi-layer MPLS-TE tunnel, is put forward in this paper.Single-layer MPLS-TE means all routers are in the same route transmitting level. SPF (the shortest path first) is adopted in the process of routing. So when a sudden flow raise happens, the shortest path in IP network becomes so congested that other longer paths in this domain cannot be fully utilized and the flow can only be controlled in a small range. Therefore, when the users in the domain get access to resources outside, congestion still exists. However, multi-layer MPLS-TE means routers can be divided into several levels and LERs (label edge routers) are set up on the edge of each level. The management router locating at the intersection of two levels controls the other routers on the same level by managing the MPLS labels within a certain range. The connection of routers on the same level or between high and low levels must find the way through the management router. So, network becomes a three-dimensional one. It is better to adopt multi-layer MPLS-TE in the intensive information technology area.Backup tunnel between two routers on the same level, which ensures free link when it fails, sets up a model called fast reroute on multi-layer MPLS-TE tunnel. When a new path is built, the old one breaks down. By that, as fast rerouting a node cannot distribute two bandwidth at the same time, some relaxation of the one-time disorder of data packets can also be brought about, and the time used to reroute can be greatly reduced to make it faster. The intersection of new path and old one is the node of tunnel. Moreover, different routers belong to different levels respectively, then when rerouting, their respective levels have no changes. The full use of the backup tunnel--the bridge between routers on the same level, minimizes the reverse flow of data transmission, so that data packets can quickly re-route along a relatively shorter path. The model has been verified by NS2.