BA 471 – Telecommunications and Networking


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  • TCP Header – Source/Dest. Port Addresses specified. Port addresses refers to what software needs to be used at source and destination.
  • At the DOS prompt, type Tracert This would provide you the routers involved in passing the packets to ebay’s web server.
  • Guided media: Message flows through a physical media such as twisted-pair (telephone wires), coax (TV cables), or fiber optic (Backbone network cables). Microwave – High frequency radio waves; Need radio towers to boost signal every 30 miles or so. All signals suffer attenuation – weakening of signal as distance traversed by signal increases. Need devices to amplify signals. Satellites – Geosynchronous Earth Orbiting Satellites (GEOS) versus Low Earth Orbiting Satellites (LEOS) GEOS: Orbit – 22,300 miles above earth’s surface; Few satellites needed for global coverage; Propagation delay (time taken for signals to travel to space and back to earth) is about 0.25 seconds; Orbital life – typically is 15+ years; Cost is about 3 billion dollars. LEOS: Orbit – 200 – 800 miles above earth’s surface; Large number of satellites needed for global coverage; Require only low power transmitters due to their proximity to earth’s surface; Negligible transmission (propagation) delay; Orbit life typically is about 5 to 9+ years. Costs less (compared to GEOS) per satellite. But you would need several LEOS to span the globe. McCaw Cellular Communication, Microsoft, Motorola, Lockheed have invested heavily in LEOS. LEOS need to travel fast to stay afloat and not fall down soon after launching (due to gravitational pull and proximity to earth’s surface). Typical speed of LEOS is about 17,000 miles per hour. At that speed they can circle earth in about 90 minutes.
  • Example of bus topology
  • Example of Ring topology The older rings supported simplex transmission (data flow only in 1 direction – clockwise or counterclockwise). The newer ring technologies (e.g. SONET) support full-duplex transmission (data can flow in both directions simultaneously)
  • Example of Star and Tree topologies
  • Example of Star and Ring topologies
  • Example of star topology
  • BA 471 – Telecommunications and Networking

    1. 1. BA 471 – Telecommunications and Networking Dr. V.T. Raja Oregon State University [email_address]
    2. 2. Outline <ul><li>Introduction </li></ul><ul><ul><li>Analogy with effective human communication </li></ul></ul><ul><li>5-layer Network Model </li></ul><ul><ul><li>A theoretical framework for our day-to-day interactions on the Internet </li></ul></ul><ul><li>Some Network Design/Topology Issues </li></ul>
    3. 3. Some Basic Characteristics of Effective Human Communication <ul><li>Sender/Receiver </li></ul><ul><li>Messages (Words) </li></ul><ul><li>Transmission Media </li></ul><ul><ul><li>Air/Printed Page </li></ul></ul><ul><li>Speak same language or have an Interpreter </li></ul><ul><li>Less noisy room (or) talk loud enough </li></ul>
    4. 4. Some Basic Characteristics of Telecommunication Networks
    5. 5. Theoretical Framework: 5-layer network model <ul><li>Application Layer (Layer-5) </li></ul><ul><li>Transport Layer </li></ul><ul><li>Network Layer </li></ul><ul><li>Data Link Layer </li></ul><ul><li>Physical Layer (Layer-1) </li></ul>
    6. 6. Protocols and addresses used at different layers of the 5-layer network model <ul><li>HTTP (Hyper Text Transfer Protocol) operates at the Application Layer. </li></ul><ul><ul><li>Example of an application layer address: </li></ul></ul><ul><li>TCP (Transmission Control Protocol) operates at the Transport Layer. </li></ul><ul><ul><li>Example of a transport layer default port address/port ID: 80 (Web); 25(E-mail) </li></ul></ul>
    7. 7. Protocols and addresses used at different layers of the 5-layer network model <ul><li>IP (Internet Protocol) operates at the Network Layer. </li></ul><ul><ul><li>Example of an IP address: </li></ul></ul><ul><li>Ethernet operates at the data link layer. </li></ul><ul><ul><li>Example of a DLL address: 00-B0-D0-B4-54-13 </li></ul></ul>
    8. 8. Application and Transport Layers <ul><li>User interfaces with application software using: </li></ul><ul><ul><li>Application layer (e.g., web/e-mail) address </li></ul></ul><ul><li>Transport layer’s major function is: </li></ul><ul><ul><li>Packetizing </li></ul></ul><ul><ul><ul><li>Breaking large messages into smaller packets at source </li></ul></ul></ul><ul><ul><ul><li>Reassembling packets at final destination </li></ul></ul></ul><ul><ul><ul><li>Creates/appends TCP header </li></ul></ul></ul><ul><ul><ul><ul><li>Packet # </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Source/Destination Port ID </li></ul></ul></ul></ul>
    9. 9. Network Layer <ul><li>Major functions of IP at network layer are </li></ul><ul><ul><li>Addressing and </li></ul></ul><ul><ul><li>Routing </li></ul></ul><ul><li>IP prepares IP header which contains: </li></ul><ul><ul><li>Source/Destination IP Address and </li></ul></ul><ul><ul><li>Routing Information </li></ul></ul>
    10. 10. Network Layer (Continued) <ul><li>Addressing </li></ul><ul><ul><li>DHCP (Dynamic Host Control Protocol) Server </li></ul></ul><ul><ul><ul><li>Assigns IP addresses to client machines requesting an IP address </li></ul></ul></ul><ul><ul><li>DNS (Domain Name Service) Server </li></ul></ul><ul><ul><ul><li>Similar to directory assistance – used for finding destination IP addresses. </li></ul></ul></ul><ul><li>Routing </li></ul><ul><ul><li>Routing tables; Routers (Tracert); Routing Protocols </li></ul></ul>
    11. 11. Data Link Layer <ul><li>Major functions of Data Link Layer are: </li></ul><ul><ul><li>Media Access Control </li></ul></ul><ul><ul><ul><li>Handling message collisions </li></ul></ul></ul><ul><ul><li>Error Detection </li></ul></ul><ul><ul><li>Error Correction </li></ul></ul><ul><ul><li>Message Delineation </li></ul></ul><ul><ul><ul><li>Identifying beginning and ending of packets – since all computer transmissions go out as 0s and 1s over the physical layer </li></ul></ul></ul><ul><li>DL layer appends a DL header and DL Trailer </li></ul>
    12. 12. Physical Layer <ul><li>Wired Media/Wireless Media: Examples </li></ul><ul><ul><li>Twisted pair; Coaxial; Fiber Optic Cables </li></ul></ul><ul><ul><li>Microwave; Satellites and Cell phones </li></ul></ul><ul><li>Internetworking Devices: Examples </li></ul><ul><ul><li>Hubs; Multiplexers </li></ul></ul><ul><ul><li>DSL/Cable Modems </li></ul></ul><ul><ul><li>Switches; Routers </li></ul></ul>
    13. 13. Network Design How to support full connectivity? <ul><li>Design the most economic internetwork between “end-user nodes” and an existing WAN </li></ul>Usernode Usernode Usernode Usernode Usernode Usernode Usernode Usernode Usernode Usernode WAN
    14. 14. Network Design Find an economic internetworking solution Usernode Usernode Usernode Usernode Usernode Usernode A direct connection to a WAN backbone node Usernode Usernode Usernode Usernode Usernode Usernode Connection via multiplexers
    15. 15. Some Network Design Issues Major Cost Components <ul><li>Acquisition and installation costs of a MUX </li></ul><ul><li>Cost of high bandwidth link between MUX and WAN (Internet) </li></ul><ul><li>Cost of low bandwidth link between end-user node and MUX </li></ul>
    16. 16. Network Design Management How to design a feasible and economical internetwork? <ul><li>Find an optimal number of MUXs to interconnect all given user nodes to some existing WAN such that ... </li></ul><ul><li>All user nodes are connected </li></ul><ul><li>User communication requirements are satisfied </li></ul><ul><li>Capacity constraints on each MUX is not violated </li></ul><ul><li>Total internetworking costs are minimized </li></ul><ul><li>Topology issues are considered </li></ul>
    17. 17. Some Network Topologies <ul><li>Star topology </li></ul><ul><li>Mesh topology </li></ul><ul><li>Bus topology </li></ul><ul><li>Ring topology </li></ul><ul><li>Physical versus logical topology </li></ul>
    18. 20. Example 1
    19. 21. Example 2
    20. 22. Example 3