  This paper studies the use of a traffic optimization technique named TCM
(Tunneling, Compressing and Multiplexing) to reduce the bandwidth of MMORPGs
(Massively Multiplayer Online Role-Playing Games), which employ TCP to provide
a soft real-time service. In order to optimize the traffic and to improve
bandwidth efficiency, TCM can be applied when the packets of a number of
players share the same link, which occurs in some scenarios, as e.g. the
traffic between proxies and servers of game-supporting infrastructures. First,
TCP/IP headers are compressed using standard algorithms that avoid sending
repeated fields; next, a number of packets are blended into a bigger one and
finally, they are sent using a tunnel. The expected compressed header size has
been obtained using traffic traces of a real game. Next, simulations using a
traffic model of a popular MMORPG have been performed in order to estimate the
expected bandwidth savings and the reduction in packets per second. The
obtained bandwidth saving is about 60 percent. Packets per second are also
significantly reduced. In addition, the added delays are shown to be small
enough so as not to impair layers' experienced quality.
