Duo to the high cost of network entity equipment environment, network laboratory is not established completely in colleges and universities in china, students find that it is difficult to grasp the complex and abstract network concepts. Virtual learning tool software named Cisco Packet Tracer is free for students in anytime, which provides the same configuration environment as true network entity equipment. This paper presents the example of Dynamic Routing Protocol (RIP), and offers experimental design topology of RIP. This teaching mode not only reduces the dependence on the real environment, but also helps students to master the abstract network concepts and enhance theirs practical operation skills. This can cultivate student's innovative spirit.

There are two protocols, which are widely used in NGN network, namely the SIP protocol and H.248 protocol. According to different application scenarios and actual need, this paper fuse two different protocol characteristics, and network model is established, these can provide suggestions for the modification of the existing network of China.

Computer network is one of the compulsory course for computer professional students, but students are boring for abstract network concepts, in order to improve the innovation of students, a virtual simulation tools named Packet Tracer is introduced into the classroom teaching, which can provide network simulation environment as real life with enough network equipment. This paper presents the configuration example of Open Shortest Path Firs Protocol, and proves the network connectivity simulation results, this is an efficient method for teaching and learning by visual emulator.

TCP Veno [1] was recently proposed to eliminate TCP performance suffering from wireless links. Real network measurements and live Internet results have validated Veno's significant throughput improvement in wireless networks and its harmonious co-existent behavior with TCP Reno connections in wired networks. In this paper, we study Veno's performance in asymmetric networks such as ADSL, HFC, where network congestion occurs on the reverse path of acks rather than on the forward path of data sending. Our real experiments demonstrate that Veno continues to reach higher throughput in these asymmetric networks, regardless of wireless or wire links being embedded. Throughput improvement up to 88% over Reno is reached

As network environment is becoming more and more complex, it is difficult for students to understand and master the complex and abstract network concepts. A virtual learning tool named Cisco Packet Tracer has been introduced into the classroom teaching, which provides the virtual configuration environment as real one. This article presents the features of the virtual simulation tool, and the configuration example for mini practice project, which can inspire students creativity. It makes teaching and learning computer network much easier than traditional teaching method.