Advertisement

Multimedia Tools and Applications

, Volume 45, Issue 1–3, pp 7–32 | Cite as

On the challenge and design of transport protocols for MMORPGs

  • Chen-Chi Wu
  • Kuan-Ta ChenEmail author
  • Chih-Ming Chen
  • Polly Huang
  • Chin-Laung Lei
Article

Abstract

Although MMORPGs are becoming increasingly popular as well as a highly profitable Internet business, there is still a fundamental design question: Which transport protocol should be used—TCP, UDP, or some other protocol? In this paper, we first evaluate whether TCP is suitable for MMORPGs, and then propose some novel transport strategies for this genre of games. Our analysis of a trace collected from a TCP-based MMORPG called ShenZhou Online indicates that TCP is unwieldy and inappropriate for MMORPGs. We find that the degraded network performance problems are due to the following characteristics of MMORPG traffic: 1) tiny packets, 2) a low packet rate, 3) application-limited traffic generation, and 4) bi-directional traffic. Since not all game packets require reliable transmission or in-order delivery, transmitting all packets with a strict delivery guarantee causes high delays and delay jitters. Therefore, our proposed transport strategies assign game packets with appropriate levels of transmission guarantee depending on the requirements of the packets’ contents. To compare the performance of our approach with that of existing transport protocols, we conduct network simulations with a real-life game trace from Angel’s Love. The results demonstrate that our strategies significantly reduce the end-to-end delay and delay jitter of packet delivery. Finally, we show that our strategies effectively raise satisfaction levels of the game players.

Keywords

Content-based transport protocol Game traffic Network performance Online games Packet delivery User satisfaction 

Notes

Acknowledgements

The authors would like to thank the anonymous reviewers for their helpful comments. This work was supported in part by Taiwan Information Security Center (TWISC), National Science Council under the grants NSC97-2219-E-001-001 and NSC97-2219-E-011-006. It was also supported in part by the National Science Council of Taiwan under the grants NSC96-2628-E-001-027-MY3 and NSC97-2221-E-001-009.

References

  1. 1.
    Allman M, Paxson V, Stevens W (1999) TCP congestion control. RFC 2581Google Scholar
  2. 2.
    Braden R (1989) Requirements for internet hosts—communication layers. RFC 1122Google Scholar
  3. 3.
    Chen K-T, Huang P, Lei C-L (2006) Game traffic analysis: an MMORPG perspective. Comput Networks 50(16):3002–3023CrossRefGoogle Scholar
  4. 4.
    Chen K-T, Huang P, Lei C-L (2006) How sensitive are online gamers to network quality? Commun ACM 49(11):34–38CrossRefGoogle Scholar
  5. 5.
    Chen K-T, Huang P, Lei C-L (2009) Effect of network quality on player departure behavior in online games. IEEE Trans Parallel Distrib Syst 20(5):593–606CrossRefGoogle Scholar
  6. 6.
    Claypool M (2005) The effect of latency on user performance in real-time strategy games. Comput Networks 49(1):52–70 (special issue on Networking Issues in Entertainment Computing)CrossRefGoogle Scholar
  7. 7.
    Claypool M, Claypool K (2006) Latency and player actions in online games. Commun ACM 49(11):40–45CrossRefGoogle Scholar
  8. 8.
    ENet (2008) ENet: an UDP networking layer for the multiplayer first person shooter cube. http://enet.cubik.org/
  9. 9.
    Floyd S, Kohler E (2006) Profile for datagram congestion control protocol (DCCP) congestion control ID 2: TCP-like congestion control. RFC 4341Google Scholar
  10. 10.
    Floyd S, Kohler E, Padhye J (2006) Profile for datagram congestion control protocol (DCCP) congestion control ID 3: Tcp-friendly rate control (TFRC). RFC 4342Google Scholar
  11. 11.
    GameDev.Net (2004) FAQ—multiplayer and network programming. http://www.gamedev.net/
  12. 12.
    Griwodz C, Halvorsen P (2006) The fun of using TCP for an MMORPG. In: NOSSDAV ’06: proceedings of the 2006 international workshop on Network and operating systems support for digital audio and video, pp 1–7Google Scholar
  13. 13.
    Harcsik S, Petlund A, Griwodz C, Halvorsen P (2007) Latency evaluation of networking mechanisms for game traffic. In: NetGames ’07: proceedings of the 6th ACM SIGCOMM workshop on network and system support for games, pp 129–134Google Scholar
  14. 14.
    Kohler E, Handley M, Floyd S (2006) Datagram congestion control protocol (DCCP). RFC 4340Google Scholar
  15. 15.
    Mathis M, Mahdavi J, Floyd S, Romanow A (1996) TCP selective acknowledgement options. RFC 2018Google Scholar
  16. 16.
    OpenTNL (2004) The Torque network library. GarageGames. http://www.opentnl.org/
  17. 17.
    Pack S, Hong E, Choi Y, Park I, Kim J-S, Ko D (2002) Game transport protocol: lightweight reliable transport protocol for massive interactive on-line game. In: Proceedings of the SPIE, vol. 4861. pp 83–94Google Scholar
  18. 18.
    Shirmohammadi S, Georganas ND (2001) An end-to-end communication architecture for collaborative virtual environments. Comput Networks 35(2–3):351–367CrossRefGoogle Scholar
  19. 19.
    Stevens RW (1995) TCP/IP Illustrated, vol 2: the implementation. Addison-Wesley, ReadingGoogle Scholar
  20. 20.
    Stewart R (2007) Stream control transmission protocol. RFC 4960Google Scholar
  21. 21.
    UserJoy Technology (2007) ShenZhou Online. http://www.ewsoft.com.tw/
  22. 22.
    Woodcock BS (2008) An analysis of MMOG subscription growth—version 23.0. http://www.mmogchart.com/

Copyright information

© Springer Science+Business Media, LLC 2009

Authors and Affiliations

  • Chen-Chi Wu
    • 1
  • Kuan-Ta Chen
    • 2
    Email author
  • Chih-Ming Chen
    • 1
  • Polly Huang
    • 1
  • Chin-Laung Lei
    • 1
  1. 1.Department of Electrical EngineeringNational Taiwan UniversityTaipeiTaiwan
  2. 2.Institute of Information ScienceAcademia SinicaTaipeiTaiwan

Personalised recommendations