Transport Protocol Dependent Communications in Different Packet Switch Architectures

Abstract

We investigated the joint influence of different packet switch architectures, controlled and uncontrolled transport layer protocols and transport flow characteristics on the packet switching performance. In network simulator ns2, three packet switch architectures were implemented and combined with UDP and TCP transport. This multilayer model thus combines mechanisms of L1-2 and L4. Additionally, flows with different mean flow size and flow size distribution were applied and the impact transport flow characteristic was analyzed. In particular, the heavy-tail distributed flows were compared to constant flow size. The switching performance measured in terms of packet loss probability and packet delay were analyzed under different traffic loads and buffer sizes. The purpose of the research was thus to understand in more detail a possible impact of new IP traffic patterns (e.g. caused by predominant share of peer-to-peer traffic and corresponding applications) on packet switching systems. The results indicate that the intrinsic characteristics of packet switch architectures reflect in the performance under different transport protocols and flows. The influence of the load or buffer space change is more manageable or predictable, even if we consider the differences among architectures. On the other hand, keeping the same overall load and just replacing the TCP transport with UDP or loading the network with heavy-tail distributed flow sizes or increasing the mean flow size results in more aggressive traffic patterns that may result in a severe deterioration of switching performance.