Chapter 19

Question 1

What is LABEL REWRITING in ATM

Answer 1

The replacement of the incoming cell’s VPI/VCI in ATM switches with a probably different VPI/VCI is called label rewriting.

Question 2

What are Permanent Virtual Circuits

Answer 2

ATM can provide customers with virtual circuits that look like traditional leased digital circuits. They are called permanent virtual circuits (PVC).

Question 3

What is provisioning

Answer 3

The forwarding table entries for such permanent VC’s are statically configured, the terms used by Telco’s for this is provisioning.

Question 4

What are two steps of provisioning

Answer 4

1. To determine a complete path

2. To choose appropriate VPI/VCI for each step in the path, and configure each adjacent pair of switches.

Question 5

What is switched virtual circuit (SVC)

Answer 5

Most networks offer dynamic connections, which last for a relatively short time. To handle this, ATM can dynamically establish a switched virtual circuit (SVC), allow it last as long as necessary and then terminate it.

Question 6

What is SIGNALING

Answer 6

The term signaling is used to describe communication about the network

Question 7

What is Quality of Service

Answer 7

Networks are more frequently being designed to allow specification of the quality of service required by users.

Question 8

What are three types of QoS specifications in ATM

Answer 8

CONSTANT BIT RATE (CBR): It is used for audio and video, since these have predefined maximum data rates.
VARIABLE BIT RATE (VBR): It is used for compressed audio and video where the data rate depends on the level of compression that can be achieved.
AVAILABLE BIT RATE (ABR): It is used for typical data applications (where the data rate may be unknown and bursty) and allows use of whatever bandwidth is available at a given time.