background image
650 Appendix A: Answers to Review Questions
26
Why would a designer want to segment a network?
Segmentation reduces traffic on the network. Reduced traffic helps high-bandwidth
applications perform better.
27
What types of cables can be used to connect computers on a Token ring network?
Token Ring cables use IBM Type 1, 2, and 3 cabling.
28
What considerations should you make when you're deciding which type of cable to select
for a network?
What distances must the cable cover?
What are the network's security needs?
How much bandwidth will be required?
What transmission speeds must be supported?
29
What type of cable is recommended for the desktop?
CAT 5.
30
Under what situations is unshielded twisted-pair cable not recommended?
Unshielded twisted-pair cable is susceptible to interference. If data must be transmitted
great distances at high speeds, unshielded twisted-pair cable is not the recommended
choice of cabling.
31
What cable is recommended for transmitting data at very high speeds over long distances?
Fiber-optic cable is not susceptible to interference. Use fiber to transmit data at very high
speeds over long distances.
Chapter 4
1
What is the size of an ATM cell, and how do its fixed length and size contribute to low
latency?
The ATM cell has a fixed length of 53 bytes--48 for the data and 5 for the header. With
the fixed length, the ATM switch doesn't have to be notified when the transmission is
done. So, the ATM switch doesn't waste overhead looking for information in software.
2
What are the two types of virtual circuits used by ATM?
ATM's flexibility allows it to run on permanent virtual circuits and switched virtual
circuits.
3
Name and describe the three layers of the ATM reference model.
The three layers of the ATM reference model are the ATM physical layer, the ATM layer,
and the ATM adaptation layer (AAL). These three layers correlate to the physical and data
link layers of the OSI model. The AAL is responsible for allowing data conversions from
multiple applications to and from the ATM cell.
87200333.book Page 650 Wednesday, August 22, 2001 1:41 PM