Design and implementation of a network-link emulator

Network-link emulator is one of the key software utilities for network emulation. After a discussion of principles to emulating a specified network-link, this paper gives control models for bandwidth, transmission delay and packet loss rate emulation. After that, three implementing schemes for the emulator are presented and discussed, and the scheme based on Netfilter is chosen finally. Based on the scheme, the emulator is implemented, and its organization is presented. Finally, throughputs and accuracy of the emulator are tested and results are discussed.