| With the rapid development of Internet applications, the network environment is becoming more and more complex. Peer-to-peer files sharing and video streaming services are increasing and these applications will consume a large part of the available bandwidth resources. In addition, the problem becomes increasingly critical as more and more inelastic traffic emerges. To solve this problem, more and more network providers use e. g. Deep Packet Inspection in combination with traffic shapers to penalize bulk data applications and users that cause large traffic volumes. But these approaches do not consider the actual congestion situation on the path, nor do they provide incentives for users to react appropriately. Fortunately, a congestion exposure mechanism (conex) proposed by IETF ConEx Working Group can solve this problem effectively.Firstly, this thesis introduces some congestion exposure mechanism related standardization organizations. Then, it describes three main congestion exposure mechanisms:ECN, Re-ECN and conex. In this thesis, the modifications of TCP/IP toward to the three mechanisms are described respectively. Especially, modifications of TCP/IP, accurate feedback solutions and related parts for conex mechanism are analysed in details.Secondly, this thesis presents two solutions based on the basic idea of the congestion exposure mechanism. One is for notifying the congestion information in a mobile communication network. The other is for exposing congestion in a tunnel scenario. Why to do them and how to do them are elaborated in these two solutions.Thirdly, this thesis also describes the simulation of Re-ECN protocol which is considered a solution of the conex mechanism. At the same time the functional test is done and the verification results are in line with expectations.Finally, this thesis summarizes the work that needs to be further improved and perfected for the two solutions and points out the further research of the conex mechanisms. |
