Monitoring Protocol Traffic with a MAGNeT

Network researchers have traditionally focused on monitoring, measuring, and characterizing traffic in the network to gain insight into building critical network components (e.g., protocol stacks, routers, switches, and network interface cards). Recent research suggests that additional insight can be obtained by monitoring traffic at the application level (i.e., before traffic is modulated by the protocol stack) rather than in the network (i.e., after traffic is modulated by the protocol stack). Thus, we present MAGNeT: Monitor for Application-Generated Network Traffic, a toolkit that captures traffic generated by the application (as it traverses the protocol stack) rather than traffic in the network. MAGNeT provides the capability to monitor protocolstack behavior, construct a library of traces of applicationgenerated traffic, verify the correct operation of protocol enhancements, troubleshoot and tune protocol implementations, and perhaps even replace tcpdump. In addition, we have extended MAGNeT to instrument CPU context switches as an example of how the general kernel monitoring mechanisms of MAGNeT can be used to monitor any kernel event in the operating system.