Chapter Summary
Slow Ethernet technology, despite its speed limit of 10Mbps, is still the most widely installed, most stable, and most viable option for migratory growth among the current standards in LAN technology. Its resilience and capability to maintain a sense of homogeneity among networks justifies its ongoing use.
At the same time, the development and increasing popularity of faster standards, such as Fast and Gigabit Ethernet, ensures the continued dominance of Ethernet as the preferred LAN installation. Even though such emergent architectures as 16Mbps Token-Ring and 100Mbps FDDI face obstacles related to their cost and relation to the dominant standards, they still offer viable alternatives as LAN solutions.
Questions and Answers
What are the differences between the channel access methods of Ethernet and of Token-Ring?
A. Ethernet uses a method called contention in which devices must contend for the right to transmit. Any device can attempt to send data at any time, but this results in collisions, so devices must wait until the channel is idle to successfully transmit. In contrast, Token-Ring uses the token-passing method whereby a device must wait for a token to become available before it has the right to transmit.
Identify the following specifications: 802.2, 802.3, and 802.5.
A. The 802.2 specification represents the implementation of the LLC sublayer of the Data Link layer. It handles framing, flow control, and errors, as well as the Network layer interface.
The 802.3 specification represents the Physical layer as well as the MAC sublayer of the Data Link layer. In addition, it uses CSMA/CD to handle access and speed over a variety of different physical media using 10 and 100Mbps Ethernet.
802.5 specifies the parameters for the use of the Physical layer and the MAC sublayer of the Data Link layer while using token passing and shielded twisted-pair cabling for Token-Ring.
What are the differences between half-duplex and full-duplex?
A. The differences between half-duplex and full-duplex are as simple as the following: With half-duplex, nodes must take turns transmitting, while with full-duplex, both nodes can transmit and receive simultaneously.
What are the similarities and differences between 10BaseX and 100BaseX?
A. The main similarities of 10BaseX and 100BaseX are frame types, frame sizes, and channel access method. The differences are encoding schemes, transfer rates, timing, and hardware.
What are the distance limitations with 10Base2, 10Base5, and 10BaseT?
A. The distance limitation for 10Base2 is 185 meters per segment. The distance limitation for 10Base5 is for segments of up to 500 meters. The practical distance limitation for 10BaseT is 100 meters.
Practice Test
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Review and identify Figure 3.22 using Cisco's naming convention.
- SAP (Service Access Protocol)
- ARPA Frame
- Novell-Ether
- SNAP
Answer C is correct because Novell-Ether is the correct naming convention. Answers A, B, and D are simply incorrect. -
Review and identify Figure 3.23 using Cisco's naming convention.
- SAP
- 802.3 RAW
- thernet_II
- Ethernet_SNAP
Answer A is correct because SAP is the correct naming convention. Answers B, C, and D are simply incorrect. -
Review and identify Figure 3.24 using Cisco's naming convention.
- Ethernet_SNAP
- 802.3 RAW
- 802.2
- ARPA
Answer D is correct because ARPA is the correct naming convention. Answers A, B, and C are simply incorrect. - Review and identify Figure
3.25 using Cisco's naming convention.
- Ethernet_II
- Novell-Ether
- SNAP
- SAP
Answer C is correct because SNAP is the correct naming convention. Answers A, B, and D are simply incorrect. -
What is the difference between the 100BaseFX and the 100BaseTX specification?
- 100BaseFX is not compatible with 802.3 but 100BaseTX is.
- 100BaseTX requires either Category 3 or 4 cable, and 100BaseFX uses fiber-optic cable.
- 100BaseFX runs over fiber-optic cable, whereas 100BaseTX runs over Category 5 cabling.
- 100BaseFX runs over Fiber-Optic cable, whereas 100BaseTX runs over Category 3 or 4 cable.
Answer C is correct because the difference between the 100BaseFX and 100BaseTX specifications is that 100BaseFX runs over fiber-optic cable, whereas 100BaseTX runs over Category 5 cabling. Answers A, B, and D are incorrect because they do not reflect the differences between the two specifications. -
What is the definition of full-duplex transmission?
- Full-duplex allows full transmission in one direction at a time.
- Full-duplex allows transmission and reception at the same time.
- Full-duplex allows one device to fully transmit while another receives.
- Full-duplex allows one device to fully receive while another transmits.
Answer B is correct because full-duplex allows transmission and reception at the same time. Answers A, C, and D are incorrect definitions of full-duplex. -
What is the definition of half-duplex transmission?
- Half-duplex allows transmission in one direction at a time, similar to a narrow one-way bridge.
- Half-duplex allows transmission and reception at the same time.
- Half-duplex allows one device to fully transmit in both directions at the same time.
- Half-duplex transmits on one machine while allowing reception in another machine.
Answer A is correct because half-duplex allows transmission in one direction at a time. Answers B, C, and D are incorrect definitions of half-duplex. -
Which IEEE specification defines token passing as opposed to token bus?
- 802.4
- 802.5
- 802.3
- 802.2
Answer A is incorrect because 802.4 defines token bus. Answer B is correct because 802.5 is the IEEE specification that defines token passing. Answer C is incorrect because 802.3 defines Ethernet's general operation, components, and distance limitations. Answer D is incorrect because 802.2 defines the implementation of the LLC sublayer of the Data Link layer. -
What is the most commonly used ring speed for Token-Ring?
- 4Mbps
- 10Mbps
- 100Mbps
- 16Mbps
Answer D is correct because the most commonly used ring speed for Token-Ring is 16Mbps. Answers A, B, and C are simply incorrect. -
What term describes the method by which FDDI recovers from a failure?
- Reverse direction
- Ring management
- Return to zero code
- Ring wrap
Answer D is correct because ring wrap is the term that describes the method by which FDDI recovers from failure. Answers A, B, and C are incorrect because they do not describe this method.
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