ECS4346 Communication Protocol Engineering

4th year subject


Length = 2 hours

Answer all questions.  All worth equal marks.



Question 1

Describe the objectives of Broadband ISDN.  What are the characteristics
of the new applications of Broadband ISDN that are not well supported
by narrowband ISDN?  Explain why ATM was chosen as the switchng technology
of Broadband ISDN.  Compare ATM technology with the circuit switching
technology used in the current narrowband ISDN.


Question 2

Compare and contrast the architecture and functionality of single stage
crossbar, multistage ATM switches, single shared bus, and multiple bus
ATM switches.  Which switch architecture would be appropriate for a
public telecommunications carrier switch with over 10,000 line
interfaces, and which switch architecture would be appropriate for an
office envrionemnt with 10 personal computers.  Explain the advantages
of self-routing over table-lookup routing in multi-stage switches.

Question 3

Define congestion and describe some techniques for preventing congestion
in a network of ATM switches.  Explain how both short term and long
term congestion may still occur despite the use of these techniques.
What techniques may be used to reduce the effect of congestion once
congestion occurs.

Question 4

Explain why dimensioning the links in an ATM network is more difficult
than the traditional problem of dimensioning links in a telephone network.
Describe and compare some alternative approaches to dimensioning links
in an ATM network.  Also describe how such techniques may be used in
connection admission control algorithms.

Question 5

Draw a signalling diagram for establishing a call from a telephone
connected to a narrowband ISDN network.  Describe how a setup message
would vary from a narrowband ISDN network and a Broadband ISDN network.
Describe how PNNI signalling is used during the establishment of a call
across an ATM network with multiple switches.  What role does PNNI have
in routing calls, and how does it scale to large private networks?