Advanced Computer Networks Course Objectives


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Advanced Computer Networks Course Objectives

  1. 1. Introduction
  2. 2. Network Definitions and Classification <ul><li>Preliminary definitions and network terminology </li></ul><ul><li>Sample application paradigms </li></ul><ul><li>Classifying networks by transmission technology </li></ul><ul><li>Classifying networks by size (or scale) </li></ul><ul><li>Classifying networks by topology </li></ul>
  3. 3. Preliminary Definitions <ul><li>computer network :: [Tanenbaum] a collection of “autonomous” computers interconnected by a single technology. </li></ul><ul><li>[LG&W] communications network ::a set of equipment and facilities that provide a service. </li></ul><ul><li>[PD] {low level definition} A network can consist of two or more computers directly connected by some physical medium such as coaxial cable or an optical fiber. Wireless connectivity needs to be included in this definition. </li></ul>
  4. 4. Network Building Blocks <ul><li>Nodes and Hosts: computers, routers, switches </li></ul><ul><li>Links: coaxial cable, optical fiber, wireless communication </li></ul><ul><ul><li>point-to-point </li></ul></ul><ul><ul><li>multiple access </li></ul></ul>P&D slide (a) (b)
  5. 5. Preliminary Definitions <ul><li>In a distributed system the collection of independent computers appears to its users as a single coherent system. </li></ul><ul><li>Namely, the distinctions lie in the transparency in assigning tasks to computers. </li></ul>
  6. 6. Switched Networks P&D slide Figure 1.3
  7. 7. internet Figure 1.4 Interconnection of networks P&D slide
  8. 8. Network <ul><li>P&D recursive definition:: </li></ul><ul><li>two or more nodes connected by a link. </li></ul><ul><li>or </li></ul><ul><li>ii. two or more networks connected by a node {an internet}. </li></ul>
  9. 9. 12 1 11 8 4 7 2 6 9 10 14 5 13 15 3 Host B Host C Host L Host D Host E Host G Host J Host A Host H Host F Host M 16 17 W T X Y Z nodes AP W1 W2 W3 W4
  10. 10. Sample Application Paradigms
  11. 11. Client-Server Applications <ul><li>Figure 1.1 A network with two clients and one server. </li></ul>Tanenbaum slide
  12. 12. Client-Server Model <ul><li>Figure 1-2. The client-server model involves requests and replies. </li></ul>Tanenbaum slide
  13. 13. Peer-to-Peer Applications <ul><li>Figure 1.3 In a peer-to-peer system there are no fixed clients and servers. </li></ul>Tanenbaum slide
  14. 14. Mobile Network Users <ul><li>Figure 1-5. Combinations of wireless networks and mobile computing. </li></ul>Tanenbaum slide
  15. 15. Classifying Networks by Transmission Technology <ul><li>broadcast :: a single communications channel shared by all machines (addresses) on the network. </li></ul><ul><li>Broadcast can be either a logical or a physical concept </li></ul><ul><li>(e.g. Media Access Control (MAC) sublayer ) . </li></ul><ul><li>multicast :: communications to a specified group. </li></ul><ul><li>This requires a group address (e.g. – multimedia multicast). </li></ul><ul><li>point-to-point :: connections are made via links between pairs of nodes. </li></ul>
  16. 16. Network Classification by Size <ul><li>Figure 1-6. Classification of interconnected processors by scale. </li></ul>Tanenbaum slide
  17. 17. Network Classification by Size <ul><li>LANs {Local Area Networks} </li></ul><ul><ul><li>Wired LANs: typically physically broadcast at the MAC layer (e.g., Ethernet, Token Ring) </li></ul></ul><ul><ul><li>Wireless LANs </li></ul></ul><ul><li>MANs {Metropolitan Area Networks } </li></ul><ul><ul><li>campus networks connecting LANs logically or physically. </li></ul></ul><ul><ul><li>often have a backbone (e.g., FDDI and ATM) </li></ul></ul>
  18. 18. Ethernet bus Ethernet hub transceivers       Figure 1.17 Leon-Garcia & Widjaja: Communication Networks Copyright ©2000 The McGraw Hill Companies Wired LANs Tanenbaum slide
  19. 19. Wireless LANs <ul><li>Figure 1-35. (a) Wireless networking with a base station. (b) Ad hoc networking. </li></ul>Tanenbaum slide
  20. 20. Metropolitan Area Networks <ul><li>Figure 1-8. A metropolitan area network based on cable TV. </li></ul>Tanenbaum slide
  21. 21. Metropolitan network A consists of access subnetworks a, b, c, d. National network consists of regional subnetworks  . Metropolitan network A is part of regional subnetwork  . A Hierarchical Network Topology 1* a c b d  2 3 4   Figure 1.8 Copyright ©2000 The McGraw Hill Companies Leon-Garcia & Widjaja: Communication Networks MAN A
  22. 22. Network Classification by Size <ul><li>WANs {Wide Area Networks} </li></ul><ul><ul><li>also referred to as “point-to-point” networks. </li></ul></ul><ul><ul><li>ARPANET  Internet </li></ul></ul><ul><ul><li>usually hierarchical with a backbone. </li></ul></ul><ul><ul><li>Enterprise Networks, Autonomous Systems (ASs) </li></ul></ul><ul><ul><li>VPNs (Virtual Private Networks). </li></ul></ul>
  23. 23. UCLA RAND TINKER USC NBS UCSB HARV SCD BBN STAN AMES AMES McCLELLAN UTAH BOULDER GWC CASE CARN MITRE ETAC MIT ILL LINC RADC Figure 1.16 ARPAnet circa 1972 a point-to-point network Leon-Garcia & Widjaja: Communication Networks Copyright ©2000 The McGraw Hill Companies
  24. 24. Wide Area Networks (WANs) <ul><li>Figure 1-10.A stream of packets from sender to receiver. </li></ul>Tanenbaum slide
  25. 25. G G G G G net 1 net 2 net 3 net 4 net 5 G = gateway Figure 1.18 Leon-Garcia & Widjaja: Communication Networks Copyright ©2000 The McGraw Hill Companies internet - a network of networks G
  26. 26. Network Classification by Topology flow of data Repeater Bus Bidirectional flow assumes baseband cable
  27. 27. Network Classification by Topology Repeater Repeater Ring Note - a ring implies unidirectional flow
  28. 28. Network Classification by Topology <ul><li>Headend </li></ul>Tree
  29. 29. Network Classification by Topology Star hub, switch or repeater
  30. 30. Network Classification by Topology Star AP W1 W2 W3 W4 Wireless Infrastructure