Q15-1. The medium of a wired LAN is guided (cable or wire); the medium of a wireless LAN is unguided (air).
Q15-3. Propagation in a wireless LAN is not confined as in a wired LAN. In a wired
LAN, propagation is confined t
Q18-1. The transport layer communication is between two ports; the network layer
communication is between two hosts. This means that each layer has a different source/destination address pair; each layer needs a different
Q20-1. According to the principle we mentioned in the text, the shortest path is the
inverse of the original one. The shortest path is G E B A.
Q20-3. Link-state routing uses Dijkstras algorithm to first create the shorte
Q17-1. An amplifier amplifies the signal, as well as noise that may come with the signal, whereas a repeater regenerates the signal, bit for bit, at the original
Q17-3. A transparent switch is a switch in which
Q19-1. The minimum length of the IPv4 header is 20 bytes and the maximum is 60
bytes. The value of the header length field defines the header length in multiples of four bytes, which means that HLEN can be between 5 and 1
Q16-1. WiMax defines a wireless WAN.
a. The fixed WiMax uses a star-topology to create a wireless WAN between a
base station (BS) and some fixed subscribed stations (FSubs).
b. The mobile WiMax also uses a star-topology t
C H A P T E R 11
Q11-1. The data link layer needs to pack bits into frames. Framing divides a message
into smaller entities to make flow and error control more manageable.
Q11-3. The answer is negative. We need to distinguish betwee
Switching provides a practical solution to the problem of connecting multiple
devices in a network. It is more practical than using a bus topology; it is more
efficient than using a star topology and a central hub. S
Communication at the network layer is host-to-host; communication at the
data-link layer is node-to-node.
Two hosts in two different networks can theoretically have the same link-layer
address because a link-la
Q10-1. In a single-bit error only one bit of a data unit is corrupted; in a burst error
more than one bit is corrupted (not necessarily contiguous).
Q10-3. In this case, k = 20, r = 5, and n = 20. Five redundant bits are
Q12-1. The answer is CSM/CD.
a. CSMA/CD is a random-access protocol.
b. Polling is a controlled-access protocol.
c. TDMA is a channelization protocol.
Q12-3. The answer is CDMA.
a. ALOHA is a random-access protocol.
The three different techniques described in this chapter are line coding, block
coding, and scrambling.
The data rate defines the number of data elements (bits) sent in 1s. The unit is
bits per second (bps). Th
The period of a signal is the inverse of its frequency and vice versa: T = 1/f
and f = 1/T.
Fourier series gives the frequency domain of a periodic signal; Fourier analysis gives the frequency domain of a nonpe
Multiplexing is the set of techniques that allows the simultaneous transmission
of multiple signals across a single data link.
In multiplexing, the word link refers to the physical path. The word channel
The transmission media is located beneath the physical layer and controlled
by the physical layer.
Guided media have physical boundaries, while unguided media are
Twisting ensures that both wir
To make the communication bidirectional, each layer needs to be able to provide two opposite tasks, one in each direction.
The router is involved in:
a. three physical layers,
b. three data-link layers,
Normally, analog transmission refers to the transmission of analog signals
using a band-pass channel. Baseband digital or analog signals are converted to
a complex analog signal with a range of frequencies suitable f
The five components of a data communication system are the sender, the
receiver, the transmission medium, the message, and the protocol.
Advantages of a multipoint over a point-to-point configuration (type of c