Research On Key Technologies Of Active Networks And Its Applications

In recent years, there is an explosive growth of Internet. With the increase of various new services and the improvement of network technologies, the traditional packets network architecture can not meet the tremendous needs of network users. Timely and effective employment of various new services and applications is seriously limited by the lack support within network.Active networks represent a quantum step in the evolution of packet-switched network by providing a programmable network interface in network nodes. Active networks not only have the basic capability of forward packets toward their destination as of traditional packet network, but also have the capability to support dynamic modification of the network's behavior as seen by user. The "active" of active networks exhibit in two aspects: Firstly, the resources of active network node are highly abstracted to a programmable network application programming interface. With this interface, the functionality of network nodes can be dynamically constructed and refined, and it could provide the more rich process capability with the packets. On the other hand, some executable programs are carried in user packets, which can execute in network nodes and change the network's behaviors as seen by user. With this capability, users can program the network on the fly to construct and refine the special services that they need.So far, the research of active networks is just on their way of initial phase, many areas of active networks such as architecture and application are still need to be research in-depth. In this dissertation, the research emphasis is focus on the architecture of active networks and the applications that benefit from active networks1. At first, the current active networks architectures are investigated in-depth, and then a novel scalable architecture of active networks in network simulation environment is given and implemented. Secondly, the active networks technology is introduced into the design of two kinds of network services, TCP congestion control and reliable multicast transport protocol, in purpose of solving their problems which are inherence in traditional network individually. With active networks principle in mind, we present some new algorithms and schemes. Lastly, these new algorithms and schemes are evaluated on our novel active network architecture network simulation platform. Simulation results not only prove the effective and innovative of our active network architecture, but also show the obvious performance improvement of our new algorithms and schemes of TCP congestion control and reliable multicast transport protocol.In chapter 2, we investigate the current active networks architectures in-depth andthen present and implement a novel scalable architecture of active networks in network simulation environment. This platform is the base to evaluate the correctness and performance improvement of new algorithm and schemes present in following chapters.In chapter 3, a congestion control algorithm FACC based on Active Networks and its modified algorithm MFACC are proposed to solve the problem that congestion control in traditional network depends on the ambiguity implication to detect network congestion and then carry out the congestion control. By providing congestion detection and congestion control mechanism in network nodes, the FACC and MFACC algorithm can not only precisely detect the network congestion and timely notify the sources, but also provide more effectively congestion control.In chapter 4, we describe the problems of reliable multicast transport protocol that effective feedback implosion avoidance, loss recovery and scoped retransmission can not be achieved in traditional network without network support. A novel reliable multicast transport protocol ARMT based on active networks is presented firstly. By providing the Loss recovery, NACK suppression and aggregation, Scoped retransmission and retransmission load distribution schemes in the network nodes, ARMT protocol can resolve the above problems.