Traffic Routing Wireless Networks — Test 1

Correct Answer: A. A. True
Explanation: The type of traffic carried by a network determines the routing services. It also determines protocols, and call handling techniques which must be employed.

Correct Answer: B. B. Virtual circuit routing
Explanation: Connection oriented services are also called virtual circuit routing. In connection oriented routing, the communications path between the message source and destination is fixed for the entire duration of the message.

Correct Answer: A. A. Datagram services
Explanation: Connectionless services are also called datagram services. In a connectionless service, a call set up procedure is not required at the beginning of a call, and each message burst is treated independently by the network.

Correct Answer: B. B. False
Explanation: First generation cellular systems provide connection oriented services for each voice user. Voice channels are dedicated for users at the serving base station.

Correct Answer: B. B. Circuit switching
Explanation: Wireless data networks are not supported by circuit switching. It is due to their short, bursty transmissions which are often followed by periods of inactivity. Circuit switching is best suited for dedicated voice only traffic.

Correct Answer: A. A. True
Explanation: Packet switching breaks each message into smaller units for transmission and recovery. When a message is broken into packets, a certain amount of control information is added to each packet to provide source and destination identification, as well as error recovery provisions.

Correct Answer: C. C. Beginning
Explanation: The header specifies the beginning of a new packet. It contains the source address, packet sequence number, and other routing and billing information.

Correct Answer: D. D. Arq
Explanation: The control field defines functions such as transfer of acknowledgments, automatic repeat requests (ARQs), and packet sequencing. The information field contains user data. And the final field is the frame check sequence field or the CRC (cyclic redundancy check).

Correct Answer: B. B. False
Explanation: In contrast to circuit switching, packet switching provides excellent channel efficiency for bursty data transmission of short length. An advantage of packet switched data is that the channel is utilized only when sending or receiving bursts of information.

Correct Answer: C. C. X.25
Explanation: X.25 was developed by CCITT (now ITU-T) to provide standard connectionless network access (packet switching) protocols for the three layers (layer 1, 2 and 3) of the open systems interconnection (OSI) model.