The unfairness of UDP traffic in routers with different buffer units

Abstract

In recent years, router buffer sizing becomes one of hot research topics. There were a variety of different views of buffer sizing presented in the literature. However, all the previous studies ignored whether buffer unit was structured in terms of packet or byte. In this paper, we find that the loss performance of routers with very small buffers is impacted by the buffer unit structure. When buffer unit is structured in terms of byte, the UDP packet loss rate is lower than the TCP packet loss rate. However, when buffer unit is structured in terms of packet, the UDP packet loss rate is higher than the TCP packet loss rate. We draw the conclusion that the different buffer units would create an unfair impact on UDP traffic. We further analyze this unexpected unfairness for UDP traffic, and present two models to explain the unfairness created by different buffer units in routers. The simulation results reveal that a smaller proportion of UDP traffic ensures low packet loss rate for TCP traffic when buffer unit is byte. When buffer unit is packet, a smaller proportion of UDP traffic ensures low packet loss rate for both TCP traffic and UDP traffic.