Design And Implementation Of A Border Router Emulation System

The Border Gateway Protocol is the only inter-domain routing protocol on the Internet. It implements routing among autonomous systems and guarantees the communication between devices connected to Internet by maintaining the reachability of IP prefixes. Due to the significance of BGP protocol, tests and experimentation can not be conducted on the Internet in order to prevent large scale network problems in case of misconfiguration. The researchers have applied simulation and emulation technologies to network protocol research and there has been a variety of BGP simulators and emulators being developed so far. However, traditional BGP emulators are not able to meet the requirement of network research due to the explosive increasing size of network and complicated network structure recently.The current BGP virtualization techniques, including BGP simulation and emulation, have issues as follows:1. Emualtion and simulation are isolated. The majority of researches divide them into two separated areas, and the limitation of this kind of isolated view makes existing tools not fully reflect features of BGP protocol.2. The amount of research on BGP simulation overweighs that on BGP emulation very much. For the moment, a lot more focus is cast on BGP simulation than emulation which leads to a relatively large gap on BGP emulation field.3. The scale of BGP simulator is limited. Since the restricted hardware resources, generally a small scale of BGP simulators can not increase with that in real Internet. There is a lack of simulation experimenting environment. Existing large scale network testbed is very hard for normal researchers, for example, college students, to access, while the small-scale experiments can not meet the requirement which makes it a dilemma.Aim at above questions, our contribution mainly includes the following four aspects.1. We design and implement a compound AS-level topology discovery method. This method can extract AS relationships from BGP routing tables and BGP update messages simultaneously and infer the topology structure of the whole network, thus providing a virtual topology basis for network emulation experiments.2. We leverage a distributed parallel architecture to implement a large-scale simulation of BGP networks. BGP simulation is deployed on multiple servers, and we try to exploit more hardware resources to expand the scale of network topology in order to keep the pace of the increasment on real Internet.3. We build a BGP emulation tool based on BGP simulation technique, and make distributed BGP emulation possible with a distributed BGP simulation basis.4. We establish a network emulation testbed with multiple access points. This system provideds more than one user-defined access points and allows multiple BGP devices exchange routing information by connecting to the testbed just like in the real Internet. Finally, experiment results show that the proposed border router emulation system can emulate a large-scale AS-level topology and provide a reliable network experiment environment.