Section 3.2: Physical and Logical Topologies, and Access Methods

Learning Objectives

After completing this section, you should be able to

• describe various LAN topologies and their uses, and the advantages and disadvantages of each;
• define switching;
• describe circuit switching, message switching and packet switching work, and examine their differences;
• explain how various access methods work.

Tasks

• Study Chapter 5 of the TD textbook.
• Complete hands-on Project 5-2.
• Complete Case Project 5-2.

Study Questions

1. What is the physical topology of a computer network?
2. What physical topologies are commonly used?
3. What are the main features of a bus topology?
4. What are the main components of a bus topology?
5. What are the main features of a ring topology?
6. What are the main components of a ring topology?
7. What are the main features of a star topology?
8. What are the main components of a star topology?
9. What is a hybrid physical topology?
10. What is a star-wired ring topology? What main features does it have?
11. What is a star-wired bus topology? What main features does it have?
12. What are daisy chain and daisy chained topology? Why is a daisy chain needed?
13. What are the main features of a daisy-chained topology?
14. What is a hierarchical topology? What are its main features?
15. What does an enterprise-wide computer network topology require?
16. What are backbone networks?
17. What is a serial backbone? What are its main features?
18. What is a distributed backbone? What are its main features?
19. What is a collapsed backbone? What are its main features?
20. What are the differences between a distributed backbone and a collapsed backbone?
21. What is a parallel backbone? What are its main features?
22. What is a mesh network? What are the main features of a mesh network?
23. What is a logical topology?
24. On what layers of OSI network reference model would the logical topology’s elements be found?
25. What are the most popular traditional network transport systems?
26. What is switching in the context of computer networking?
27. What is circuit switching?
28. How does circuit switching work?
29. What are the advantages and disadvantages of circuit switching?
30. What is message switching?
31. How does message switching work?
32. What are the advantages and disadvantages of message switching?
33. What is packet switching?
34. How does packet switching work?
35. What are the advantages and disadvantages of packet switching?
36. What are packets?
37. What is Ethernet’s access method?
38. How are computer networks specified in the 100BaseT Ethernet networking standard?
39. How are computer networks specified in the 100BaseTX Ethernet networking standard?
40. How are computer networks specified in the 100BaseT4 Ethernet networking standard?
41. How are computer networks specified in the 100BaseVG Ethernet networking standard? What does the VG stand for?
42. How does CSMA/CD work?
43. What does CSMA/CD stand for?
44. What is a collision in data transmission on Ethernet? How does it happen? How is it resolved?
45. What is a jamming in data transmission on Ethernet? How does it happen? How is it resolved?
46. What is a collision domain on an Ethernet network?
47. What is data propagation delay? How long does it take for data travel across a 900-M cable at 1.8*10^8 M per second?
48. Why is an appropriate propagation delay important for Ethernet?
49. Why do different Ethernet network standards support different lengths of network segments?
50. What is the demand priority access method used by 100BaseVG?
51. What network topology does a demand priority network run on?
52. Why do data collisions not happen on demand priority network?
53. What is an intelligent hub? Where is it needed?
54. What is a shared Ethernet?
55. What are the differences between shared and switched Ethernet networks in terms of both advantages and disadvantages?
56. How does switched Ethernet increase the effective bandwidth of a network segment?
57. What are the main features of 1-Gigabit and 10-Gigabit Ethernet?
58. What are some commonly used Ethernet data frames?
59. What are the differences between different Ethernet data frames?
60. How can you specify the type of frame used on a given Ethernet network?
61. On which layer of OSI reference model does data framing occur?
62. Why may a single data frame carry any one of many higher-layer protocols?
63. What data are common among all types of Ethernet frames?
64. What is padding in data framing? Why is padding necessary?
65. What are minimum and maximum Ethernet frame sizes, respectively?
66. Why does each Ethernet frame contain a 7-byte preamble?
67. What data is behind a 7-byte preamble in an Ethernet frame?
68. Which IEEE committee is in charge of all Ethernet network standards?
69. Why is the IEEE 802.3 frame also called the LLC frame? How is it designated in the Novell lexicon?
70. What is the structure of an IEEE 802.3 frame?
71. What information is contained in the LLC field of an IEEE 802.3 frame?
72. What is a service access point?
73. What does the frame check sequence (FCS) do?
74. What mathematical algorithm is used to generate an FCS?
75. What is the difference between the IEEE 802.3 frame and the Novell proprietary 802.3 fame?
76. What are the differences between Ethernet II frame and IEEE 802.3 frame?
77. How does an Ethernet II frame identify the upper layer protocol contained in the frame?
78. Where did the IEEE 802.3 SNAP frame come from?
79. Why is a good knowledge of frame types important in learning about computer networking?
80. How can multiple frame types be used on a network?
81. What are the main design considerations for Ethernet networks?
82. Which company developed token ring technology?
83. What are the main features of token ring networks?
84. What are the main features of high-speed token ring?
85. How do token ring networks work?
86. What does the active monitor in a token ring network do?
87. What is a token? How is a token passed around a token ring network?
88. Which IEEE standard gives the token ring specification?
89. How many addressable stations can be connected to a token ring network?
90. How is an addressable station connected to a token ring network?
91. What cables and connectors are used for token ring networks?
92. What is a media filter? What is its job?
93. How can a token ring network benefit from network switching?
94. What is the format of an IBM token ring frame?
95. What are the main considerations for token ring networks?
96. What is FDDI? What are the advantages and disadvantages of FDDI technology?
97. What are the main features of FDDI?