Computer Science 825
                         Quiz 9           Name _______________________

1. a. In SDLC do supervisory frames carry a frame sequence number xor
      an ack number?  (Yes is not a correct answer)





   b. In SDLC unnumbered frames carry no sequence number or ack number
      at all.  This would appear to make it impossible to construct
      a reliable protocol (one in which exactly one copy of each frame
      transmitted is accepted by the receiver).  Is such the case? If
      not why not? If so, why doesn't this cause problems.







   c. Explain the meaning of the P/F bit found in the control byte
      of all SDLC frames.







2. Assume a new virtual circuit is added to the network shown on the
   screen. Its route is ABCD. What are the new entries in each nodes
   routing tables:

   A      ->        E      ->         F       ->         B




3. a. What is one good reason why virtual circuit service at the network
      layer is viewed as superior to datagram service.



   b. What is one good reason why datagram service at the network
      layer is viewed as superior to virtual circuit service.





4. a. Name one nonadaptive routing algorithm and cite the principal
      disadvantage associated with its use.






   b. Name one isolated adaptive routing algorithm and cite the principal
      disadvantage associated with its use.