Linux Bandwidth Management Technology Research And Applications

With the development of Internet, new applications were increased quickly, more and more people want to enjoy high-speed network service. So far, network capacity is beyond people's demands. In fact, a majority of bandwidth is occupied by some applications with low priority, which leads to no guarantee for many critical applications. In order to ensure the limited network resources are used fairly and efficiently, finally increase the quality of service, a strategy which can limit the bandwidth of every user and each application is required to allocate the finite bandwidth, the strategy is called bandwidth management.As an operating system being widely adopted in network equipment, Linux has supported Qos long before. After constantly kernel optimization and support form open source software, nowadays, Linux provides extremely strong and integrated bandwidth management mechanism.This thesis deeply studies the two major module of Linux's bandwidth management--Netfilter and Traffic Control (TC). Netfilter is a packet filtering framework in Linux kernel; it implements much functionality, such as packet filtering, connection tracking, packet marking, etc. TC manages the data flow, its numerous and powerful queuing discipline algorithms and classifiers can make complicated traffic control. In this thesis, token bucket filter and hierarchical token bucket are specially discussed. A bandwidth management system based on Linux is designed. The system consists of 3 modules: user bandwidth management, traffic differentiating and traffic control. the first module limits every user's possession of bandwidth; the main functionality of traffic differentiating module is to differentiate the data flow and mark them for the use of next module, Aho-Corasick algorithm is employed to implement a simple protocol analysis scheme, also discusses the future of traffic differentiating based on the implementation of some open source software and commercial equipment; traffic control module uses different policies to different applications according to the mark traffic differentiating module provides, carries out the Qos tragedy ultimately.