%0 Journal Article
%T Analyzing the Effect of TCP and Server Population on Massively Multiplayer Games
%A Mirko Suznjevic
%A Jose Saldana
%A Maja Matijasevic
%A Juli¨¢n Fern¨¢ndez-Navajas
%A Jos¨¦ Ruiz-Mas
%J International Journal of Computer Games Technology
%D 2014
%I Hindawi Publishing Corporation
%R 10.1155/2014/602403
%X Many Massively Multiplayer Online Role-Playing Games (MMORPGs) use TCP flows for communication between the server and the game clients. The utilization of TCP, which was not initially designed for (soft) real-time services, has many implications for the competing traffic flows. In this paper we present a series of studies which explore the competition between MMORPG and other traffic flows. For that aim, we first extend a source-based traffic model, based on player¡¯s activities during the day, to also incorporate the impact of the number of players sharing a server (server population) on network traffic. Based on real traffic traces, we statistically model the influence of the variation of the server¡¯s player population on the network traffic, depending on the action categories (i.e., types of in-game player behaviour). Using the developed traffic model we prove that while server population only modifies specific action categories, this effect is significant enough to be observed on the overall traffic. We find that TCP Vegas is a good option for competing flows in order not to throttle the MMORPG flows and that TCP SACK is more respectful with game flows than other TCP variants, namely, Tahoe, Reno, and New Reno. Other tests show that MMORPG flows do not significantly reduce their sending window size when competing against UDP flows. Additionally, we study the effect of RTT unfairness between MMORPG flows, showing that it is less important than in the case of network-limited TCP flows. 1. Introduction Massively Multiplayer Online Role-Playing Games (MMORPGs) have become one of the most profitable genres in the gaming industry. The leading MMORPG in the market, namely, World of Warcraft (WoW) by Activision Blizzard, at its peak, had approximately 12 million players [1], and it reported around one billion US dollars of profit in 2010. MMORPG players demand interactive virtual worlds, so a good underlying network quality is needed. In other words, the traffic generated by virtual worlds of MMORPGs has very high quality of service demands in terms of delay and packet loss. While MMORPGs are real-time multiuser virtual worlds, many of them use TCP for communicating the actions of the player to the server and vice-versa. The use of TCP as a transport protocol is not very widespread in the area of networked games. Besides flash based web games, TCP is not that common. Most of the games which feature full real time 3D virtual worlds use UDP, including First Person Shooters (FPS), racing, Real Time Strategy (RTS), and Multiplayer Online Battle Arena (MOBA).
%U http://www.hindawi.com/journals/ijcgt/2014/602403/