network game research – introduction and counter- strike analysis mark claypool
TRANSCRIPT
Network Game Research –Introduction and Counter-
strike Analysis
Mark Claypool
Outline● Overview of Network Games● Net Games Conference● Research Issues● Analysis Counter-strike● Our Results
Why Study Games?● Rapidly increasing in popularity
– Forrester Research: 18 million on-line in 2001– Consoles on-line
● Playstation 2 on-line (9/2002)● Xbox Live (12/2002)
– Cell phones● Doom port (Nokia)
● Design networks to better accommodate traffic
Game Types● First Person Shooters
– Doom, Quake, Counter-strike, …● Massive Multi-Player Online Role Playing
– Everquest, Earth and Beyond, …● Real-Time Strategy
– Warcraft, Starcraft …● Other
– Misc – not any genre above● Example: Diablo2, Racing, …
– Non-networked● Example: Thief
– Multiplayer, but relaxed real time ● Example: Chess, Bridge
Net-Games - Workshop on Network and System Support for
Games● First was 2002 in Braunschweig, Germany
– http://wwwmc.tm.uni-karlsruhe.de/netgames2002/
● Second is in Redwood City, California– http://confman.eecs.umich.edu/netgames2003/
● Sponsored by:– ACM– Electronic Arts– Microsoft
Net-Games Program Committee– Sugih Jamin, University of Michigan (Chair)– Mostafa Ammar, Georgia Institute of Technology– Grenville Armitage, Swinburne University of Technology– John Buchanan, Electronic Arts– Jon Crowcroft, University of Cambridge– Christophe Diot, Sprintlabs– Wu-chang Feng, Oregon Health and Science University– Carsten Griwodz, University of Oslo– Jim Kurose, UMass at Amherst– John Laird, University of Michigan– Brian Neil Levine, UMass at Amherst– Martin Mauve, University of Mannheim– Hiroyuki Morikawa, University of Tokyo– Dan Rubenstein, Columbia University– Srinivasan Seshan, Carnegie Mellon University– Wilson Yuen, City University of Hong Kong– Lars Wolf, TU Braunschweig
Net-Games Topics● Multi-player game architectures and platforms ● Prevention and detection of cheating ● Games on mobile and resource-scarce devices ● AI and techniques for latency hiding ● Modeling, usage studies, and characterization ● Enabling protocols for networked games ● Systems support for authentication and
accounting ● Put research issues here
Provisioning On-line Games: A Traffic Analysis of a Busy
Counter-Strike Server
Wu-chang Feng, Francis Chang, Wu-chi Feng, Jonathan Walpole
Goal● Understand the resource requirements of
a popular on-line FPS (first-person shooter) game
Why FPS?● While there are other game types …● Gaming traffic dominated by first-person
shooter genre (FPS) [McCreary00]
Networked FPS lineage
Doom
Doom II Quake + QuakeWorld variants + Team Fortress + Capture the Flag
Quake II + Soldier of Fortune + Heretic II
Quake III Arena + Medal of Honor Allied Assault + Return to Castle Wolfenstein + Soldier of Fortune 2 + Jedi Knight II
Doom III
Half-Life + Counter-Strike + Day of Defeat + Urban Terror + Team Fortress Classic + Team Fortress 2
Unreal
Unreal Tournament
Unreal Tournament 2003 + America's Army: Operations
8 of top 10 games derivedfrom one of two lineages
About the game...● Half-Life modification● Two squads of players competing in
rounds lasting several minutes● Rounds played on maps that are rotated
over time● Each server supports up to 32 players
What is Counter-strike (CS)?
What is Counter-strike (CS)?
What is Counter-strike (CS)?
About the game...● Centralized server implementation
– Clients update server with actions from players– Server maintains global information and
determines game state– Server broadcasts results to each client
● Sources of network traffic– Real-time action and coordinate information– Broadcast in-game text messaging– Broadcast in-game voice messaging– Customized spray images from players– Customized sounds and entire maps from
server
Why CS?
Neverwinter Nights
America's Army: Operations
Soldier of Fortune 2: Double Helix
Unreal Tournament 2003
Return to Castle Wolfenstein
Unreal Tournament
Battlefield 1942
Quake III Arena
MedalOfHonor: Allied Assault
Half-Life
0 20000 40000 60000 80000 100000
Serverspy FPS rankings (10/31/2002)
# of players
Why CS?
Action Half-Life
Front Line Force
Vampire Slayer
SvenCo-op
Firearms
The Specialists
Deathmatch
Team Fortress Classic
Day of Defeat
Counter-Strike
0 10000 20000 30000 40000 50000 60000 70000 80000
Serverspy HL mod rankings (10/31/2002)
# of players
The Trace● cs.mshmro.com (129.95.50.147)
– Dedicated 1.8GHz Pentium 4 Linux server– OC-3– 70,000+ unique players (WonIDs) over last 4
months ● One week in duration 4/11 – 4/18● 500 million packets● 16,000+ sessions from 5800+ different
players
A week in the life...
Variance time plot
(Normalized to base interval of 10ms)
Less variance < 50msRemains to 30 minDecreases above 30 min
Digging deeper
Interval size=10ms Interval size=50ms
● Periodic server bursts every 50ms– Game must support high interactivity– Game logic requires predictable updates to
perform lag compensation
Digging deeper● Low utilization every 30 minutes
– Server configured to change maps every 30 minutes
– Traffic evenly pegged otherwise....
Interval size=1sec Interval size=30min
Finding the source of predictability● Games must be fair across all mediums
(i.e. 56kers)– Aggregate predictability due to “saturation of
the narrowest last-mile link”
Packet sizes● Supporting narrow last-mile links with a high
degree of interactivity requires small packets– Clients send small single updates– Servers aggregate and broadcast larger global
updates
Implications● Routers, firewalls, etc. must be designed
to handle large bursts at millisecond levels– Game requirements do not allow for loss or
delay (lag)– Should not be provisioned assuming a large
average packet size [Partridge98]– If there are buffers anywhere, they must...
● Use ECN (no, doesn’t use TCP)● Be short (i.e. not have a bandwidth-delay product
of buffering)● Employ an AQM that works with short queues
– Rate-based not Queue-based
Implications● ISPs, game services
– Must examine “lookup” utilization in addition to link utilization
– Concentrated deployments of game servers may be problematic
● Large server farms in a single co-lo● America's Army, UT2K3, Xbox
On-going work● Other pieces in the provisioning puzzle
– Aggregate player populations– Geographic distributions of players over time
(IP2Geo)
● Impact on route and packet classification caching
● Other FPS games– HL-based: Day of Defeat– UT-based: Unreal Tournament 2003, America's Army– Quake-based: Medal of Honor: Allied Assault– Results apply across other FPS games and
corroborated by other studies
Future work● Games as passive measurement infrastructure
– Only widespread application with continuous in-band ping information being delivered (measurement for free)
– “Ping times” of all clients broadcast to all other clients every 2-3 seconds
– 20,000+ servers, millions of clients
● Games as active measurement infrastructure– Thriving FPS mod community and tools– Server modifications [Armitage01]
● Other game types
Some Net-Games Research at WPI
● Mark Claypool, David LaPoint, and Josh Winslow. “Network Analysis of Counter-strike and Starcraft”, In Proceedings of the 22nd IEEE International Performance, Computing, and Communications Conference (IPCCC), Phoenix, Arizona, USA, April 2003. Online at: http://www.cs.wpi.edu/~claypool/papers/net-game/
● Compared FPS (Counter-strike) with RTS (Starcraft)
● Smaller number of traces● Controlled set of users
Our Results● Confirms packet sizes for Counter-strike● Starcraft results:
– Packets smaller– Linear increase with number of players
● Starcraft traffic much smoother (bandwidth usage) than Counter-strike– Counter-strike bursty during ‘fire-fights’
● (PEDS talk later)
Network Game Research –Introduction and Counter-
strike Analaysis
Mark Claypool