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Computer Networks 2002/2003

This article explores the design principles of network architecture, focusing on scalability, robustness, and configurability. Topics include elements of network architecture, local area networks, wide area networks, and standardization efforts.

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Computer Networks 2002/2003

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  1. Computer Networks2002/2003 Network Architecture Johan Lukkien Johan J. Lukkien, j.j.lukkien@tue.nl TU/e Computer Science, System Architecture and Networking

  2. Network Architecture • Elements • Nodes (hosts) • Interconnect (wires + repeaters/hubs) • Topology • Software • stack Johan J. Lukkien, j.j.lukkien@tue.nl TU/e Computer Science, System Architecture and Networking

  3. Network architecture design • Generality: do not limit the scope unnecessarily • avoid use-specific designs • Robustness • node & link failure: local impact • limit effect of malfunctioning • e.g. domains • stability: left to itself the system converges to a defined & useful state • e.g. no global reboots • removing malfunctioning component is enough • fault resilience • detection: auto-diagnose • Byzantine behavior Johan J. Lukkien, j.j.lukkien@tue.nl TU/e Computer Science, System Architecture and Networking

  4. Network architecture design • Scalability • design works for small and large networks • e.g., performance, exploitation of locality • extensions possible • Configurability • automatic (cf. stability), local configuration • tweakable: optimizable for certain conditions • Determinism • Migration & evolution Johan J. Lukkien, j.j.lukkien@tue.nl TU/e Computer Science, System Architecture and Networking

  5. Architecture and distance home networks wireless networks long-distance wire-less Johan J. Lukkien, j.j.lukkien@tue.nl TU/e Computer Science, System Architecture and Networking

  6. Local area networks • Typically, based on shared medium • broadcasting at layer 1 or layer 2 • Relatively small distance (few kilometers, at most) • Simple topologies • 10Base2 ethernet • Star: 10(0)BaseT • Token ring • ownership (token) passed around • owner puts packets on an removes them from the ring • owner puts token on the ring again • medium can be shared as well as point-2-point Johan J. Lukkien, j.j.lukkien@tue.nl TU/e Computer Science, System Architecture and Networking

  7. Local Area Networks • High total bandwidth (the shared medium is fast) • Limited number of nodes • Low delay and error rate • Broadcast facility supported • i.e., part of the layer 2 service • All nodes equal • though some a bit more than others.... Johan J. Lukkien, j.j.lukkien@tue.nl TU/e Computer Science, System Architecture and Networking

  8. Standardizing LANs: IEEE 802 • Working Groups and Study Groups • 802.1 Higher Layer LAN Protocols Working Group • Try to unify some issues for all LANs: management, addressing, bridges • 802.2Logical Link Control working Group • Issues in connecting to the network layer • 802.3 Ethernet Working Group • 802.4 Token bus Working Group • 802.5 Token ring Working Group • 802.11 Wireless LAN Working Group • 11a, 11b, 11e, 11g • 802.15 Wireless Personal Area Network (WPAN) Working Group • e.g. BlueTooth, ... • 802.16 Broadband Wireless Access Working Group • wireless MAN • 802.17 Resilient Packet Ring Working Group • 802.18 Radio Regulatory TAG • 802.19 Coexistence TAG • 802.20 Mobile Broadband Wireless Access (MBWA) Working Group • Link Security Executive Committee Study Group    Johan J. Lukkien, j.j.lukkien@tue.nl TU/e Computer Science, System Architecture and Networking

  9. Metropolitan Area Networks • Three components • the access network for end-users • at the end-user you may find a LAN again... • connect to long-haul access points • specifically serve enterprises • e.g. file storage, disparate locations • Requirements • diverse access technology • xDSL, cable, telephony, fiber • diverse managerial domains • home/enterprise equipment, PTT, cable company, leased lines • locally: fast, reliable and fair • similar technologies as LAN, if possible Johan J. Lukkien, j.j.lukkien@tue.nl TU/e Computer Science, System Architecture and Networking

  10. MANs: examples • Regular, special purpose networks • cable TV: just broadcasting and multiplexing of signals across the same physical medium • telephony: full duplex, point to point, connection oriented • electricity • General data communication • re-use existing infrastructure Johan J. Lukkien, j.j.lukkien@tue.nl TU/e Computer Science, System Architecture and Networking

  11. Cable and telephony • Cable • need to add two-way communication • sharing of cable segments • Telephone • low bandwidth UTP Johan J. Lukkien, j.j.lukkien@tue.nl TU/e Computer Science, System Architecture and Networking

  12. Wide Area Networks • Long-range geographical distribution • Separation of local net and subnet • different management • subnet: just transport – wires, switches, routers (no hosts!) • Path-oriented transport through the subnet • Note: subnet properties will affect WAN services Johan J. Lukkien, j.j.lukkien@tue.nl TU/e Computer Science, System Architecture and Networking

  13. Routing (path oriented) Johan J. Lukkien, j.j.lukkien@tue.nl TU/e Computer Science, System Architecture and Networking

  14. Internetworks • Connecting distinct networks • add a subnet: WAN • connect using multi-ported devices in an existing network • e.g. WAN-connected LANs • No clear terminology for Internetworks but • must have different technologies • and different managerial domains • Note: • technicaldistinctions (WAN, LAN, MAN...) are vanishing • managerial distinctions are most relevant Johan J. Lukkien, j.j.lukkien@tue.nl TU/e Computer Science, System Architecture and Networking

  15. Wireless • Bandwidth sharing in cells • Two modes • point-to-point • base-station (star) • Overlap issues • Three distance scales • Wire-replacement • LAN technology • WAN technology Johan J. Lukkien, j.j.lukkien@tue.nl TU/e Computer Science, System Architecture and Networking

  16. Wireless (cnt’d) • Wire-replacement • relatively low bandwidth : main focus on system interconnect (BlueTooth, wireless USB); P2P • cells roughly 10m • LAN technology • include link layer technology • ‘high’ bandwidth (i.e., only a factor of 10-100 slower than wired); e.g. HiperLan, IEEE 802.11 (‘WiFi’) • cells up to 100m • P2P or base-stations • WAN technology • use long-haul connections, e.g. GSM, GPRS, UMTS • cells up to 3 km • base-stations Johan J. Lukkien, j.j.lukkien@tue.nl TU/e Computer Science, System Architecture and Networking

  17. Home networks • Special requirements • diverse hardware and interconnect • Information, Communication, Entertainment, Control • must work, reliable, foolproof • low cost • much streaming, rather than bursty traffic • high capacity • does not work well with ethernet • evolutionary path • equipment is there for years to stay • safe, secure, privacy protection Johan J. Lukkien, j.j.lukkien@tue.nl TU/e Computer Science, System Architecture and Networking

  18. Connecting everything: the Internet Johan J. Lukkien, j.j.lukkien@tue.nl TU/e Computer Science, System Architecture and Networking

  19. Exercises • Exercise 38 on page 84 Johan J. Lukkien, j.j.lukkien@tue.nl TU/e Computer Science, System Architecture and Networking

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