Advances in Network Emulation

摘要

When developing network protocols and applications it is important to be able to test them under realistic large scale wide area network conditions. One approach for performing this work is to use network emulation tools. Network emulation enables interaction between real hosts running actual network protocol implementations and applications in a controlled and repeatable environment in which a virtual network is modeled. This paper provides a survey of network emulation tools and examines advances that have been made to improve the scalability of these tools. Some emulators insert an emulation layer into the protocol stack that intercepts packets and models network characteristics such as delay and packet loss. Improved scalability has been achieved by modeling more than one virtual network node on each physical network node and by increasing the number of physical network nodes used to model the virtual network. Other emulators incorporate a real-time network simulator to model the virtual network. Improved scalability for this type of emulator has been achieved by using parallel discrete event simulation and through a hybrid flow abstraction technique where detailed packet flows can interact with fluid flows.