S38.110/Spring 1999
26.4.1999
Prof. Raimo Kantola:
Possible questions in the exam in 14.5.1999

The list is meant as a guideline for preparing to the exam. For the exam itself the list is not necessarily exhaustive.

## General

1. What is Network topology and what are the factors defining the choice of topology for a particular network?
2. Addressing in different telecommunications networks.
3. The role of dial-up connectivity in telecomm. networks and the task of the switching matrix.
4. Generations of the Switching systems  and their life cycles.
5. PCM frame structure and the PCM principles.
6. Describe the principles of PCM speech coding.
7. HDB3 line coding

## Switching

8. Give two examples of 16x16 space switch matrix implementation
9. Stucture and function of a time switch, also an alternative solution
10. Principle of  multiplexing a switching matrix.
11. Analyze the properties of a 2-stage switching matrix.
12. Draw a 3 stage rearrangably non-blocking 16 PCM’s switch as using the 3-dimensional space switch representation.
13. Analyze the properties of TST, TSS and STS switches.
14. Define the terms: strict-sense non-blocking, rearrangably non-blocking.
15. Give an example of a graf representation of a switch  and of a 3-stage switching matrix.
16. Define the Paull's matrix representation for a 3-stage Clos network
17. General representation of 3 stage switch and Clos network as its special case.
18. Under what conditions is a Clos network rearrangably non-blocking and when is it strictly non-blocking?
19. Give the Clos theorem and its proof.
20. Show how the search of a path in a Clos network can be performed.
21. Describe the generic principle of  building a switching matrix using recursion. When is the resulting switching matrix rearrangably non-blocking and when is it strictly non-blocking?
22. Draw using recursion an 8 inputs Benes network. Show what is  the number of stages and the number of cross points in a Benes network.
23. Draw recursively a strict-sense non-blocking N x N switching matrix using  N1/2 x  N1/2   switch elements.   Calcluate the number of cross points in the matrix.
24. Describer the structure of a Cantor network.
25. Prove  that a Cantor network is strict-sense non-blocking.
26. What is the number of simultaneous point to point connections in a switching matrix as a function of the number of inputs and output. What is the number of multipoint  connections. Visualize.
27. Give the proof  that a Benes network is a near optimal rearrangably non-blocking switching matrix using the calculus of point to point connections in a switching matrix.
28. Describer the principles of self-routing. Give an example of a connection in a self-routing network.
29. What are the limitations of self-routing and how they could be overcome?
30. What are the main problems of the multi stage switches?
31. What are the key technological parameters affecting the choise of a suitable architecture of a switch.
32. Describe the structure of Switch matrix of  the DX 200 switching system.
33. The advantages and drawbacks of  a matrix structured switch?

## Synchronization

35. Calculus.
36. Define jitter and wander. What is their impact to a telecom network.
37. The goals and principles of network synchronization.
38. Define Maximum time interval error (MTIE).
39. The functions of the synchronisation subsystem in a Switching System.

## Signalling - part 1

40. Give the pricipal structure of a signaling system as a state machine using both algebraic and graph representation for the state machine. Describe also the signaling flow chart method and compare it to the state machine method as a description and specification method.
42. Subscriber line signaling.
43. Principles of R2 signaling.
44. What are the limitations of line associated signaling? How does CCS7 help to overcome those limitations?
46. What are  the reliability and real-time requirements for CCS7 ?
47. Describe the functional structure of CCS7.
48. Describe the functional structure of MTP.
49. Define the terms used in MTP: signaling link, link set, signaling route, signalling route set.
50. Describe the message types in MTP and give the structure of the MTP information message.
51. Give an example that animates the concept of network in MTP.
52. Describe the addressing mechanisms in SCCP.
53. Global title in SCCP:ssä. Give an example.
55. Describe the structure of basic access in ISDN and the reference points defined for the basic access.
56. Basic access activation procedure in ISDN.
57. Describe the algorithm of an HDLC -transmitter and receiver using pseudocode.
58. Principles of DSS1 signaling and the connection establishment procedure.

## Signaling - TCAP

59. What is the purpose of TCAP, describe also its structure. Compare TCAP with  OSI.
60. Describe TCAP functional principles and operation types.
61. Describe the principle of unstructured dialogue in TCAP.
62. Describe the structured dialogue in TCAP.

## Signaling - V5

63. V5 achitecture and interfaces. Use of V5 signaling and its impact to competition on the telecom markets.
64. What has to be specified nationally for V5 signaling?
65. V5.1 ja V5.2 interfaces and main type of services for subscribers.
66. Distibution of functions in  V5.x  specifications.
67. Draw and describer the block diagram and  of  the V5.1 protocol arkhitecture.
68. Draw and describe the block diagram of the V5.2 protocol architecture.
69. Describe the use of C-channels in V5 and their control protocol.
70. Implementation of ISDN -signaling in V5.
71. Functional structure and most important messages of the PSTN protocol in V5.
72. Describe the call-by call connection control in a V5 subscriber access node.
73. Describe  the principles of the V5.2  link control for the access node to LE links.

## Signaling - ISUP

74. Describe the mechanisms for call identification in ISUP.
75. Succesfull call setup in ISUP-signaling using a signallin flow diagram.
76. How is the compatibility of consecutive ISUP versions managed?
77. Describe the method of specification for interworking of message based signaling systems.

## Signaling - MAP

78. MAP development phases, compatibility of MAP-versions.
79. Addressing principles of MAP -messages in a GSM-network.
80. Describe the use of  TCAP services by MAP.
81. Location management procedures in MAP.
82. Terminating call routing in GSM
83. MSC-to-MSC handover in MAP.
84. Security operations in MAP.
85. Subscriber management operations in MAP
86. GSM-supplementary services operations in MAP.
87. USSD-service and its function.
88. GSM short message service from the point of view of MAP.
89. Routing and addressing of short messages over GSM.
90. The goals and phases of CAMEL specifications. Describe also the phase 1 CAMEL-architecture.
91. Originating and terminating call prosedures according to CAMEL.

## Fault tolerance

92. Calculus on combinatorial reliability problems and  Markov chains.
93. Define failure, fault, error, fault-tolerance. Give a classification of  faults.
94. Define formally Reliability, availability, maintainability.
95. Define formally MTTF, MTBF, MTTR.
96. Describe the fault-tolerance principles of a telephone exchange.
97. Define mathematically failure rate in the event space {system is operational in a time interval, system fails in the interval}. Show this gives raise to the exponential reliability function.
98. Show that MTTF= 1/l

## IP Telephony

99. Describe the (prevailing) protocol stack used in IP Telephony.  Define the main functions of each
protocol in the stack.
100. Describe the network scenarios in IP Telephony.
101. Define the factors of Quality of Service in IP Voice. What are the principal means to maintain and
improve the quality of IP Voice.
102. What are the functional entities according to H.323. Define also the main functions of the the entities.
103. List the call modes supported by H.323. Draw an example of a call mode suitable for a call between
5 parties two of which are connected to a LAN and three are using a remote network connection.
104. Define the concept of Zone in H.323.
105. Describe the use of addresses in IP Telephony according to H.323.
106. Define the tasks of a gateway and a gatekeeper in H.323.
107. Describe the functions of RAS-signalling in H.323.
108. Describe the principles of call signalling in H.323.
109. Describe the functions of H.245 signalling in IP Telephony.
110. Describe the functions and use of RTP in IP Telephony.
111. Describe the functions and use of RTCP in IP Telephony.