On characteristic features of the application level delay distribution of TCP congestion avoidance
Ralf Lübben, Markus Fidler · 2016
TCP is widely used for delay-sensitive applications including video streaming, voice, and instant messaging. Therefore, a performance parameter of interest is the end-to-end delay at the application level. In the past, much research was performed in the optimization of TCP's throughput. Besides throughput, delay is an important issue in todays networks. However, it was often disregarded. Amongst others, extensive queueing inside the network induces large delays that account for a significant share of the end-to-end delay. This phenomenon is termed bufferbloat. We show that another reason for extensive delays is queueing in the TCP stack that originates primarily from TCP's congestion control. We analyze this using the analogy of a queueing model for end-to-end delays from simulating TCP's congestion control mechanism. The causes of these delays could be identified and the connection between basic TCP mechanisms and network dimensioning and configuration is presented.