An empirical evaluation of TCP performance in online games.
ABSTRACT A fundamental design question to ask in the development of a network game is—Which transport protocol should be used—TCP, UDP, or some other protocols? Seeking an ob- jective answer to the choice of communication protocol for MMORPGs, we assess whether TCP, a popular choice, is suitable for MMORPGs based on empirical evidence. To the best of our knowledge, this work is the first evaluation of transport protocol performance using real-life game traces. We analyze a 1, 356-million-packet trace from ShenZhou Online, a TCP-based, commercial, mid-sized MMORPG. Our analysis indicates that TCP is unwieldy and inappropri- ate for MMORPGs. This is due to four distinctive charac- teristics of MMORPG traffic: 1) tiny packets, 2) low packet rate, 3) application-limited traffic generation, and 4) bi- directional traffic. We show that because TCP was origi- nally designed for unidirectional and network-limited bulk data transfers, it cannot adapt well to MMORPG traffic. In particular, the window-based congestion control and the fast retransmit algorithm for loss recovery are ineffective. Fur- thermore, TCP is overkill, as not every game packet needs to be transmitted in a reliably and orderly manner. We also show that the degraded network performance did impact users' willingness to continue a game. Finally, we discuss guidelines in designing transport protocols for online games.
Full-textDOI: · Available from: Kuan-Ta Chen, May 28, 2015
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