Data Communications I


      Exam questions  19.6.2003

      1. When  you surf the Internet and click open an URL-link, you get, presented on the screen of your PC,
      a page from a remote computer.
      a) What is happening in the application layer? What application layer functions and protocols are needed?
         What messages and in what order are sent in the application alayer? (8 p)
      b) What is happening in the transport layer? What transport layer functions and protocols are used?
         What messages and in what order are sent in the transport layer? (12 p)

      2. Ethernet
      a) Explain how the Ethernet MAC (medium access layer) layer functions when sending  a frame to the Ethernet. (8 p)
      b) Why does the Ethernet frame have a minimun length? Why does the Ethernet frame have a maximum length? (4 p)
      c) In what different ways Ethernet LANs can be interconnected to form bigger networks?
         What are the pros and cons for each way? (8 p)


      3. Distance vector routing
      a) What information is kept in the routing tables when distance vector is used? How do the routers update
         their routing information? (8 p)
      b) Show, by using examples, how 'good news are speading fast'  and 'bad news are speading slowly' when distance
         vector routing is used. What solutions have been provided for this problem? (8 p)
      c) What other problems there are for distance vector routing? (4 p)