Dynamic Right-Sizing: a Simulation Study

Virtually all network applications requiring reliable end-to-end communication depend on TCP. Unfortunately, the performance of any stock TCP is abysmal over wide-area networks (WANs) and even over local-area networks (LANs) with very high-bandwidth links. Currently, network researchers manually optimize TCP buffer sizes to achieve acceptable performance over a given connection. Unfortunately, this manual optimization requires changes to the kernel on both end hosts involved in the network connection (changes that are only effective for connections between these two hosts). Furthermore, because two administrative domains must be coordinated to perform this optimization, this process can be tedious and time consuming. To address these problems, this paper illustrates the benefits of a new technique called dynamic right-sizing. This technique dynamically and automatically determines the best buffer size, and hence flow-control window size in TCP. Our simulation study shows that dynamic right-sizing can improve the performance of flows by two orders of magnitude over stock TCP implementations that have static flow-control windows.