Research On QoS Guarantee Based On Multi Nexthop Routing Mechanisms

Over the past decade, the study of guarantee IP QoS never stops, but has been staying in the model level. The relevant protocols and algorithms are still discussed in theory and never have engineering research. InterServ, DiffServ and QoS routing model are not into the mature phase of business operations. Go into the reasons, one of the key problems is that the network nodes responsible for routing for a given IP addresses has only one path to available in the existing system, namely the traditional QoS guarantee techniques are studied based on the single nexthop routing mechanism. How to achieve QoS assurance techniques based on multi-nexthop routing mechanism? This study is focus on the issue.Relying on the Nation 863 Program "A multi-nexthop routing scheme based on node potential-oriented", the author study QoS assurance techniques based on multi-nexthop routing scheme. The research is based on multi-routing mechanism of node potential-oriented, makes the differentiated services concept of DiffServ model as a reference and lets effective use of network transmission resources as the guidelines, focuses on the technology system and project implementation of multi-nexthop routing QoS guarantee. Paper is in accordance with the idea "routing: the generating multi-nexthop route, using: choosing the next hop, and the key technologies" to elaborate.The main contents are as follows:1) The breadth-first search sequence potential multi-nexthop routing algorithm is proposed. It determines potential value of the node with the order joined the search tree and according to certain rules generate routing table. The effectiveness of path generated by proposed routing algorithm is proved in theory. Comparing with existing multi-nexthop routing algorithm based on extended shortest path, it produces more available nexthops, has low complexity, and is good at balancing the network traffic.2) Proposes a mechanism matching capability of hierarchical nexthops to forward packets for QoS with the multiple nexthops. Packets belonging different service level are transported by nexthops which are appropriate to this service level and the network layer implements differentiated services. So the service with different levels competing for limited single nexthop link resources is avoided. And then the average packet delay exceeds the one of DiffServ. At the same time, this method has properties of connectionless, differentiation service in the network layer and low complexity.3) Proposed a QoS assurance technique based on selecting optimal nexthop. It selects a best nexthop from multiple nexthop links for transporting packets to ensure a certain degree of QoS. For applying this technique a path selection algorithm is proposed. The algorithm overcomes the shortage that path selection parameter used by current path selection algorithm is too single and then route decision is based on local information. As a result, path selection performance of proposed algorithm is significantly better than before and the computational complexity is same.4) The algorithm adjusting traffic between subsets with different performance are discussed. It is based on the idea "careful use of good resources, good resources for the business" to adjust traffic. So the average packet delay is still within a certain range and still better than DiffServ. For balancing load within same subset, a classification algorithm for adjusting traffic is presented. It is composed with two parts: initial traffic segmentation and local adjustment. Simulation results show that the algorithm can balance network traffic well.5) Proposed a multi-grade failure recovery mechanism using local information to complete re-routing options. Multi-nexthop failure recovery mechanism is combined with above two technologies respectively and let them to support a certain degree of network survivability. The analysis of failure recovery time shows that the multi-grade failure recovery mechanism is better than the existing survival mechanism in the failure recovery time. At the same time, it has better resource utilization performance.The study of QoS guarantee technology based on multi-nexthop routing mechanism is in the initial stage. We can summarize initial experience that: the proposed QoS guarantee technologies can use local technology to improve global network resource utilization, be easy to project implementation and algorithm is adjustment flexible and scalable. However, traffic flow, especially the traffic flow aggregation model describes traffic uncertainty that is still the nature factor to affect the performance of QoS guarantee technology. Therefore, with the conditions of fuzzy characteristics and violent change of traffic, robust path selection algorithm is a breakthrough in the direction of future research.