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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 toMultiplayer Network Technology Thomas Lidy
Introduction • Networking - used in ... • e-commerce • training & education • distributed engineering & design • entertainment • multi player games • „networked virtual environments“ Introduction toMultiplayer Network Technology
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
Networked Virtual Environment • components • graphics engines and displays • communication and control devices • processing systems • data network Introduction toMultiplayer Network Technology
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
Origins in military • SIMNET • started 1983 • developed for DARPA • DIS (protocol) • defined after 1989 • standardized packets (PDUs) • distributed & heterogeneous Introduction toMultiplayer Network Technology
Origins in industry • SGI - Flight (1984) • SGI - Dogfight (1985) Academic origins Flight • NPSNET (1986) • PARADISE (1993) • BrickNet (1991) Introduction toMultiplayer Network Technology
Origins on PC class machines • Doom (1993) • Macintosh: • Marathon (1994) • Bolo (tank game) Doom • ... and many others Bolo Introduction toMultiplayer Network Technology
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
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
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
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
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
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
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
Multicast routing New York Moscow Washington London Tokyo Denver Prague Munich Vienna Graz Introduction toMultiplayer Network Technology
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
Overview (1) Introduction toMultiplayer Network Technology
Overview (2) Introduction toMultiplayer Network Technology
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
The End Thomas Lidy