The problem of using a best-effort network for online games
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The document discusses the challenges of utilizing besteffort networks for online gaming, specifically addressing efficiency and quality issues due to the real-time requirements of these services. Various optimization strategies, such as traffic prioritization and multiplexing, are suggested to combat problems like latency and packet loss while enhancing user experience. The presentation highlights the impacts of user context and system differences on gaming quality of experience (QoE) and emphasizes the need for adaptive solutions in network support for online games.
![System impact - genres
Difference between game genres
250
Tollerated one way delay [ms]
-
200
150
100
50
0
FPS
RPG
Game genre
RTS](https://image.slidesharecdn.com/nimev6-140115100046-phpapp01/85/The-problem-of-using-a-best-effort-network-for-online-games-16-320.jpg)
![MMORPG optimization
Can this be adapted to MMORPGs?
- Higher savings, due to the use of TCP (with
a lot of ACKs)
TCP ACKs without payload
Seven IPv4/TCP client-to-server packets of World of Warcraft. E[P]=20bytes
η=80/360=22%
One IPv4/TCMTF packet multiplexing seven client-to-server WoW packets
η=80/175=45%
saving](https://image.slidesharecdn.com/nimev6-140115100046-phpapp01/85/The-problem-of-using-a-best-effort-network-for-online-games-32-320.jpg)
The problem of using a best-effort network for online games
- 1. THE PROBLEM OF USING A BESTEFFORT NETWORK FOR ONLINE GAMES NIME WORKSHOP. IEEE CCNC 2014
- 2. Index I. Real-time services on the Internet II. The two problems III. Adapting the network
- 3. Real-time services - Real-time services are being widely used: VoIP, video conference, online gaming
- 4. Real-time services In this presentation, we will focus on online gaming. Why?
- 5. Popularity of online games
- 6. Popularity of online games
- 7. The approach Client-server architecture - Consistency of the game - Cheating avoidance - Billing
- 8. How does it look? (On the packet level) 40 50 60 70 80 90 100 110 bytes 0 10 20 30 40 50 60 70 ms Unreal Tournament 40 50 60 70 80 90 100 110 bytes 0 10 20 30 40 50 60 70 ms Counter Strike I 40 50 60 70 80 90 100 110 bytes 0 10 20 30 40 50 60 70 ms Quake III
- 9. Index I. Real-time services on the Internet II. The two problems III. Adapting the network
- 10. - Still there are problem(s) Efficiency problem: Sending very frequent updates containing small volume of information is not efficient - - Not everybody has fast connections with excess bandwidth Quality problem: Using a best effort network for a real-time service - Online games present very stringent realtime requirements: players are really difficult to satisfy We need to measure quality, in terms of network parameters.
- 11. Efficiency problem If I have to send a big file, I divide it in chunks of 1500 bytes, and I may have an efficiency of 97% One IPv4/TCP packet 1500 bytes η=1460/1500=97% IPv4 TCP
- 12. Efficiency problem But real-time services cannot wait. They need information every (e.g.) 20 ms, so efficiency gets really bad (33%): One IPv4/UDP/RTP VoIP packet with two samples of 10 bytes η=20/60=33% IPv4 UDP RTP codec G.729a, 2 samples
- 13. Quality problem: QoE for games S. Möller, S. Schmidt, and J. Beyer, “Gaming Taxonomy: An Overview of Concepts and Evaluation Methods for Computer Gaming QoE,” in International Workshop on Quality of Multimedia Experience, QoMEX, 2013, pp. 1–6.
- 14. User impact - More experienced players demand more! M. Suznjevic, L. Skorin-Kapov, and M. Matijasevic, “The Impact of User, System, and Context factors on Gaming QoE a Case Study Involving MMORPGs”, The 12th Annual Workshop on Network and Systems Support for Games, 2013., p. 6
- 15. Context impact - Player’s surrounding s (other players) have an impact on QoE scores! M. Suznjevic, L. Skorin-Kapov, and M. Matijasevic, “The Impact of User, System, and Context factors on Gaming QoE a Case Study Involving MMORPGs”, The 12th Annual Workshop on Network and Systems Support for Games, 2013., p. 6
- 16. System impact - genres Difference between game genres 250 Tollerated one way delay [ms] - 200 150 100 50 0 FPS RPG Game genre RTS
- 17. Network side - Major parameters: Delay, jitter, packet loss - Fixed networks - Stable Very low packet loss and jitter Delay is still an issue - Mobile networks - Huge growing market Worse network conditions Variation of network parameters
- 18. How do we fight network delay? - Client side prediction - QoS-enabled home devices (traffic prioritization) - Traffic shaping - Dedicated networks - Geographical server distribution - Optimization of server locations - Lag compensation mechanisms (moving server time into the past)
- 19. Index I. Real-time services on the Internet II. The two problems III. Adapting the network
- 20. Adapting the network - Different solutions in order to enhance the network support for online games - Traffic optimization - Traffic prioritization - Latency reduction methods
- 21. Adapting the network - Different solutions in order to enhance the network support for online games - Traffic optimization - Traffic prioritization - Latency reduction methods
- 22. VoIP optimization - Voice trunking between two offices:
- 23. VoIP optimization - Savings of 50% are achievable . . . Context . . . Context IP Network . . . MUX+COMP Real-Time DEMUX+DECOMP Tunneling-Compressing-Multiplexing Real-Time . . .
- 24. VoIP optimization - RFC 4170 (2005) deploys this, also compressing the header payload payload ECRTP ... ECRTP RTP UDP IP PPP Mux PPP L2TP VoIP IP One IPv4/UDP/RTP VoIP packet with two samples of 10 bytes η=20/60=33% 40 to 6-8 bytes compression Five IPv4/UDP/RTP VoIP packets with two samples of 10 bytes η=20/60=33% One IPv4 TCMTF Packet multiplexing five two sample packets η=100/161=62% saving
- 25. Optimization - A trade-off appears: - Efficiency problem: we are improving it, since we are saving bandwidth and reducing pps - Quality problem: We are adding an additional delay
- 26. Game traffic optimization - Can we do the same with games? - Is there any scenario where a number of game traffic flows share the same path?
- 27. Game optimization scenarios - Between the network provider and the game company Home network with a number of users (e.g. Internet Café, access shared by neighbours) Individual DSL xDSL router DSLAM ISP aggregation network Network of the service provider xDSL router ISP network DSLAM 2 LTE access network Application server BRAS Serving Gateway Evolved NodeB eNB Internet ISP aggregation network Internet Router (ISP) Internet Router (Service provider) MUX/DEMUX
- 28. Game optimization scenarios - The end user (e.g. internet café) deploys the multiplexing Home network with a number of users (e.g. Internet Café, access shared by neighbours) xDSL router With multiplexer embedded DSLAM Individual DSL xDSL router Without multiplexer ISP network Transport network BRAS Internet Router Internet
- 29. IETF proposal: TCM-TF Tunneling, Compressing and Multiplexing Traffic Flows draft-saldana-tsvwg-tcmtf-05 draft-suznjevic-tsvwg-mtd-tcmtf-02 payload payload RTP payload payload RTP UDP TCP UDP UDP IP IP IP IP ECRTP Compression layer No compr. / ROHC / IPHC / ECRTP PPPMux Multiplexing layer PPPMux / Other L2TP Tunneling layer GRE / L2TP MPLS IP a) TCRTP Network Protocol IP b) TCMTF
- 30. One IPv4/TCP packet 1500 bytes η=1460/1500=97% FPS optimization Efficiency improvement IPv4, IPv6 One IPv4/UDP/RTP packet of VoIP with two samples of 10 bytes η=20/60=33% One IPv4/UDP server-to-client packet of Counter Strike with 9 players One IPv6/TCP packet 1500 bytes η=160/188=85% η=1440/1500=96% Four IPv4/UDP client-to-server packets of Counter Strike η=61/89=68% One IPv4/TCM packet multiplexing four client-to-server Counter Strike packets saving η=244/293=83% One IPv6/UDP/RTP packet of VoIP with two samples of 10 bytes η=20/80=25% One IPv6/UDP server-to-client packet of Counter Strike with 9 players η=160/208=77% Three IPv6/UDP client-to-server packets of Counter Strike η=61/109=56% One IPv6/TCM packet multiplexing three client-to-server Counter Strike packets η=183/246=74% saving
- 31. FPS optimization Bandwidth saving IPv4 IPv4 10 ms 5 players IPv4 10 ms 20 players 60% IPv4 reached IPv4 theoretical 50% 40% 30% 20% 10% 0% Quake 2 Unreal Tournament Counter Strike 1 Quake 3 Enemy Territory Counter Strike 2 Halo 2 Quake 4
- 32. MMORPG optimization Can this be adapted to MMORPGs? - Higher savings, due to the use of TCP (with a lot of ACKs) TCP ACKs without payload Seven IPv4/TCP client-to-server packets of World of Warcraft. E[P]=20bytes η=80/360=22% One IPv4/TCMTF packet multiplexing seven client-to-server WoW packets η=80/175=45% saving
- 33. MMORPG optimization TCMTF Bandwidth Saving, TCP/IPv4, World of Warcraft tm 50% 45% 40% 35% BS 30% 25% 20% 100 players 15% 50 players 10% 20 players 5% 10 players 0% 10 20 30 40 50 60 period (ms) 70 80 90 100
- 35. Extra slides
- 36. The approach The network is the part that I do not control - Big amount of data in my hard disk (size of WoW folder) - Small packets (interactivity requires frequent updates)
- 37. The two problems - Efficiency problem - If I use IPv6 (the next version of the protocol, with a huge number of different addresses), the efficiency only drops to 96% One IPv6/TCP packet 1500 bytes η=1440/1500=96% IPv6 TCP
- 38. The two problems - Efficiency problem - But for real-time services it becomes even worse: only one byte out of four is useful information! One IPv6/UDP/RTP packet of VoIP with two samples of 10 bytes η=20/80=25% IPv6 UDP RTP codec G.729a, 2 samples
- 39. System impact - protocols - TCP is sometimes used for games (usually MMORPGs) - Delayed acknowledgments Nagle algorithm A lot of “pure” ACK packets Protocol MMORPGs TCP World of Warcraft, Lineage I/II, Guild Wars, Ragnarok Online, Anarchy Online, Mabinogi UDP EverQuest, City of Heroes, Star Wars Galaxies, Ultima Online, Asherons Call, Final Fantasy XI TCP/UDP Dark Age of Camelot
- 40. VoIP optimization - We merge the packets and make them share the header: 1 flow 2 flows 3 flows
- 41. Game optimization scenarios - The game company places a multiplexer in the ISP network Home network with a number of users (e.g. Internet Café, access shared by neighbours) DSLAM Individual DSL Network of the service provider ISP aggregation network xDSL router ISP network Application 1 server Internet xDSL router BRAS Internet Router (ISP) LTE access network Serving ISP Gateway Evolved NodeB aggregation network MUX/DEMUX of the Service eNB Provider, hosted by the ISP Application 2 server Internet Router (Service provider) MUX/DEMUX
- 42. VoIP optimization - RFC 4170 savings (50%): TCMTF Bandwidth Saving, RTP/UDP/IPv4 voice G.729a, 2 samples per packet 60% 50% 40% 30% 20% 10% 0% 20 19 18 17 16 15 14 13 12 11 10 Number of calls 70% 9 8 7 6 5 85% prob. of reduced header 4 3 2 100% 1
- 43. FPS optimization Significant savings (Counter Strike) Bandwidth Saving 35% 30% 25% BS 20% 15% 20 players 10% 15 players 10 players 5% 5 players 0% 5 10 15 20 25 30 period (ms) 35 40 45 50
- 44. Shooting around the corner - The same problems we can find in VoIP. - Instead of having two users talking at the same time, we have the “shooting around the corner” problem.
- 45. VoIP Jack Wang Question Are you there? time Network delay scheme Answer
- 46. Online games “Shooting around the corner” Jack Wang Wang
- 47. Online games “Shooting around the corner” Wang: Dead Jack Wang Wang
- 48. Online games “Shooting around the corner” Wang: Dead Jack ¡¡¡ #%$& !!! Wang
- 49. Online games “Shooting around the corner” Jack Game server Wang Position 1 Position 2 time Shot Wang DEAD Network delay scheme
- 50. Game traffic optimization A period is defined, and all the packets arrived are compressed and multiplexed Native traffic ... Multiplexed traffic . . . PE PE PE PE ... ...
- 51. Multiplexing Bandwidth saving IPv6 IPv6 10 ms 5 players IPv6 10 ms 20 players 60% IPv6 reached IPv6 theoretical 50% 40% 30% 20% 10% 0% Quake 2 Unreal Tournament Counter Strike 1 Quake 3 Enemy Territory Counter Strike 2 Halo 2 Quake 4