Unit Three Objectives        CSCI 361      Introduction to Computer Networks
Tobin Maginnis				   Updated: 30-Mar-09

Computer Networks, 4th ed - Chapter 3 - The Datalink Layer - A. S. Tanenbaum
 0)Define a "UART" and describe the six steps of character reception.
   a)Universal Asynchronous Receiver Transmitter
   b)When the line is in the space condition (logical zero), the receivers
     samples the line 16 times the data rate. (In other words, a data interval
     is equal to 16 clock ticks. In this way the receiver can determine the
     beginning of the start bit and "move over" to the center of the bit time
     for data sampling.
   c)When the line goes into the mark state, the receiver declares a "looking
     for start bit" condition and wait one half the bit interval or eight
     clock ticks.
   d)Sample the line again and if it has not remained in the mark condition,
     consider this to be a spurious voltage change and go back to step one.
   e)If the line was still in the mark state, then consider this a valid start
     bit. Shift the start bit into an eight-bit shift-register and wait one
     bit time or 16 clock ticks.
   f)After one bit time sample the line (the data should have been there for
     the last eight clock ticks, and should remain for eight more clock ticks).
     Now shift the sample into the shift-register.
   g)Continue steps four and five seven more times. After the eighth shift,
     the start bit will "migrate" into a flip-flop indicating character
     received. Go to step one.
   http://en.wikipedia.org/wiki/Uart
 1)Define framing as an error control strategy and give its design tradeoff.
 2)Explain why timing is too inefficient as an error control tool.
 3)Describe character count framing and give its design weakness.
 4)Define in-band signaling and describe two examples of frame stuffing.
 5)Describe three possible ways a data frame could be lost.
 6)Describe two type of error detection methods and give the tradeoff between
   two types of error correction methods.
 7)Give the four fields of a frame explaining what is missing and why.  
 8)Describe the four steps in the utopia sender1 or receiver1 procedures.  
 9)Contrast a "delayed" protocol versus an asynchronous (stop-and-wait)
   protocol.
10)Explain how simple frame retransmission based on an acknowledge character
   or time-out condition would still allow errors to occur.
11)Explain why a modulo 2 sequence number is adequate to remove the error in
   protocol 2, the stop-and-wait protocol.
12)Describe the three differences between protocol 2 (stop-and-wait) and
   protocol 3 (PAR) and explain the effect of premature time-outs on the PAR
   protocol.  
13)Give the four possible scenarios of PAR frame transmission and reception.  
14)Define "piggy-backing" and give three advantages & one disadvantage for
   its use.
15)Define "Sliding Window" and describe the wire-like "essence" of all sliding
   window protocols.
16)Describe the three differences between the PAR and sliding window protocols.
17)Describe how protocol four, the sliding window protocol, can survive 
   early-frame time-out problem and explain how it still has a weakness which
   can lead to doubling network traffic.
18)Explain how the combination of a long transit time, high bandwidth, and
   short frames create extreme inefficiency.
19)Define "pipelining" and give two ways of dealing with errors and give the
   design tradeoff.
20)Explain why sequence numbers must be two times the buffer size in sliding
   window protocols.
21)Contrast "SDLC," "ADCCP," "HDLC," "LAP," and "LAPB", and describe the
   contents of the six fields in a typical bit-oriented frame (11 parts). 
Omit)Describe the two ways the P/F is employed in a bit-oriented frame.  
Omit)Describe the three types of bit-oriented control fields.  
Omit)Describe the four types of bit-oriented supervisory sub-fields.  
Omit)Contrast "SNRM," "SABM," "SABME," and "SNRME."
26)Give an overview of PPP (five parts). 

Computer Networks, 4th ed - Chapter 4 - The Medium Access Sublayer
27)Define "Ethernet," describe the CSMA/CD protocol, and describe "binary
   exponential backoff."
Omit)Describe four types of Ethernet cabling, in terms of segment lengths,
   number of stations, and today's use.
Omit)In terms of Ethernet, define "reflection," "termination," and "connector
   configuration" and explain why these implementation issues are not found
   in fiber-optic Ethernet adapters.
Omit)Support or refute the idea that we should use high speed point-to-point
   connections among routers instead of wasting bandwidth simulating a
   broadcast network. (Consider 4/16 Mbs token ring for your answer.)
31)Give a strategy to run a LAN through a building. (wiring closets & repeaters)
32)Define "Manchester Encoding" and describe its role relative to Nyquist.
33)Describe an Ethernet frame format and explain how it may or may not
   interact with the length of the broadcast medium.
   http://en.wikipedia.org/wiki/Jumbo_Frame
Omit)Describe the operation of "collision domains" in an Ethernet switch.
35)Describe the modifications to allow 100 Mbs and 1 Gbs Ethernet (5 parts).
   http://en.wikipedia.org/wiki/IEEE_802.3
   http://en.wikipedia.org/wiki/Gigabit_ethernet
   http://en.wikipedia.org/wiki/10_Gigabit_Ethernet
   http://en.wikipedia.org/wiki/100_Gigabit_Ethernet
36)List five justifications for employing a LAN bridge.
Omit)List three incompatibilities among LANs and the resulting design
   constraints  for the bridge builder and LAN manager.
38)Define bridge, describe the three "routing" steps employed in a "transparent"
   LAN bridge, and explain why or why not this is really routing.
39)Explain why spanning trees are required in  LAN (three parts) and list the
   three steps a transparent bridge employs to construct a spanning tree.