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Introduction to Multiplayer Network Technology

Introduction to Multiplayer Network Technology. Thomas Lidy. Introduction. Networking - used in ... e-commerce training & education distributed engineering & design entertainment multi player games  „networked virtual environments“. Networked Virtual Environment. software system

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Introduction to Multiplayer Network Technology

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  1. Introduction toMultiplayer Network Technology Thomas Lidy

  2. Introduction • Networking - used in ... • e-commerce • training & education • distributed engineering & design • entertainment • multi player games •  „networked virtual environments“ Introduction toMultiplayer Network Technology

  3. Networked Virtual Environment • software system • multiple users interact in real-time • shared sense of space and time • realistic 3D graphics and sound • a way to communicate • interaction with the virtual environment Introduction toMultiplayer Network Technology

  4. Networked Virtual Environment • components • graphics engines and displays • communication and control devices • processing systems • data network Introduction toMultiplayer Network Technology

  5. Origins of virtual environments • origins in military (and industry) • academic research in networked virtual environments • virtual worlds on PC class systems- 3D games Introduction toMultiplayer Network Technology

  6. Origins in military • SIMNET • started 1983 • developed for DARPA • DIS (protocol) • defined after 1989 • standardized packets (PDUs) • distributed & heterogeneous Introduction toMultiplayer Network Technology

  7. Origins in industry • SGI - Flight (1984) • SGI - Dogfight (1985) Academic origins Flight • NPSNET (1986) • PARADISE (1993) • BrickNet (1991) Introduction toMultiplayer Network Technology

  8. Origins on PC class machines • Doom (1993) • Macintosh: • Marathon (1994) • Bolo (tank game) Doom • ... and many others Bolo Introduction toMultiplayer Network Technology

  9. Network Technology • Issues for networking • Latency • time required from one host to another • Bandwidth • data rate: how many bits per second • Reliability • how much data is lost Introduction toMultiplayer Network Technology

  10. 0 65535 0 65535 0 65535 TCP UDP Other Prot. Sockets and Ports • allow multiple applications to use the network Applications ftp www netVEs games port #s protocols IP layer IP (Internet Protocol) Introduction toMultiplayer Network Technology

  11. Internet Protocol (IP) • low-level protocol • basic services • splits & reassembles packets • TTL field („time to live“) • other protocols lie on top of IP Introduction toMultiplayer Network Technology

  12. Transmission Control Protocol (TCP) • layered on top of IP ( TCP/IP) • simple point-to-point connection • automatic acknowledgments • error checking • correct packet order • reliability Introduction toMultiplayer Network Technology

  13. User Datagram Protocol (UDP) • also layered on top of IP • connectionless • packet-by-packet basis • best-efforts delivery (not reliable) • less processing time  faster • deal with packet loss and ordering! Introduction toMultiplayer Network Technology

  14. IP Broadcasting • instead of sending multiple copiesof a packet to all destinations • single transmission to all hosts in the network • broadcasting to address 255.255.255.255 • disadvantages: • expensive for hosts that are not interested • delivery only on LAN - not Internet-wide! Introduction toMultiplayer Network Technology

  15. IP Multicasting • receiver-controlled distribution • interested hosts subscribe to a list • packets are sent down distribution paths • no burdens for hosts not interested • less overhead than broadcasting • appropriate for Internet use Introduction toMultiplayer Network Technology

  16. Multicast routing New York Moscow Washington London Tokyo Denver Prague Munich Vienna Graz Introduction toMultiplayer Network Technology

  17. IP Multicasting • addressing • pseudo IP (class D address):range 224.0.0.0 - 239.255.255.255 • can be used temporarily or reserved by IANA • problems • routers must be multicast-capable • not yet available troughout the Internet • multicast routers communicate directly with each other through the MBONE Introduction toMultiplayer Network Technology

  18. Overview (1) Introduction toMultiplayer Network Technology

  19. Overview (2) Introduction toMultiplayer Network Technology

  20. Networking today - Conclusion • networking:essential part of multi player environments • designers must carefully selectprotocols and network archtitecture • multicasting: most efficient technique for large-scale netVEs • games today use client/server, peer-to-peer • multicasting probably becomes more globally available with IPv6 Introduction toMultiplayer Network Technology

  21. The End Thomas Lidy

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