Research On The Key Technology Of The Optimization For Routing Delay In Content Centric Networks

The content of the network become more and more important in the future Internet. However, the content-based transmission technique of currently TCP/IP network and the entire model confront a great challenge under the rapidly growth of the content traffic and the improvement of the users’ QoS requirement. The research of new network architecture, such as the Content Centric Networks, has achieved much fruit and more and more attention. The main ideas of the Content Centric Networks are node cache and the routing mechanism of network directly facing the data content. As a new content routing model, naming mechanism, forwarding strategy and content query is not perfect, which therefore cause the routing delay more and more huge. Routing delay in the content centric networking is mainly reflected on two aspects :(1)The problem in network transmission delay: CCN routing still use the traditional network model and route the request to the source server content providers to get content and the data transmission path is too long which increase the content acquisition delay.(2) The problem in node dealing delay: The name of the CCN network is unique and variable- length. The routing scale become more and more huge without che cking and identifying the repetitive elements when query the routing table. And also, the traditional matching algorithm is related with the length of the name which are not suit with the CCN networks and low efficiency.This study focused on the research on the key technology of CCN routing delay optimization. First of all, we propose a leading routing mechanism for neighbor content store to get the content rapidly which decrease the length and the delay of content request. Then according to the scale of p roblems existing in the aspect of content routing node, we propose a multi-path routing aggregation algorithm and a query algorithm based on hash code content, realize the routing table size compression and fast matching purposes. The researches in the dissertation are as follows:1. A leading routing mechanism for neighbor content storeFirstly, through building the fast routing table, the nodes announce the information of content store to the neighbors and get the content from the best nodes. Secondly, the mechanism can get the caches of the nodes around quickly and decrease the length of the request transmission path, optimize the request forwarding time. The theoretical analysis and the simulation results show that, this mechanism adequately uses the neighbor content and effectively decreases the average network delay by 5ms. The server load is reduced by 30%.2. Nexthop-Selectable Aggregation Based on Suffix Digest for Forwarding Information BaseThis paper proposes a Nexthop-Selectable Aggregation method based on suffix digest for FIB and adopt the multi-path routing method to select the best path to aggregate the prefix which has the public path. The method can reduce the number of table size and compress the routeing table under the filter of Bloom.Theoretical analysis and results show that Nexthop-Selectable FIB aggregation method based on suffix digest can reduce the FIB sizes to below 20% and the success probability can be close to 100% with the growing number of hash functions of Bloom Filter.3. Content routing lookup mechanism based on Hash codingThis paper presents an effective component hash encoding mechanism.Firstly, data names are compressed using hash function. Secondly, a rapid longest prefix matching of names is realized by adopting improved state transition array. Finally, a fast incremental upadate mechanism is proposed to meet the modify and delete operations in NDN forwarding process. Simulation results show that, the routing entries compression ratio achieves 40% and matching rate increases by 10%.