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The instructions and questions for the final year exam of the computer networks unit (unit 64ee3038) for the bsc (hons) information technology, media technology, and computing and network technologies degree programs at the manchester metropolitan university. The exam covers topics such as the atm forum, b-isdn reference model, link management, ip packets over atm networks, lan emulation, transport layer, and link state routing.
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Examination for the BSc (HONS) INFORMATION TECHNOLOGY FINAL YEAR BSc (HONS) MEDIA TECHNOLOGY YEAR THREE BSc (HONS) COMPUTING AND NETWORK TECHNOLOGIES YEAR THREE
Wednesday 2 June 2004
9.30 am to 12.30 pm
Instructions to Candidates
Answer FIVE questions.
(b) Explain the purpose of each element of the B-ISDN Reference model shown in Figure Q1 and state the equivalent OSI layer for each of the layers shown in the model. [10]
The B-ISDN ATM reference model
Figure Q
(c) Discuss the similarities and differences between the ATM reference model and the TCP/IP reference model. [6]
Plane Management
Layer Management
Control Plane User Plane
Upper Layers (^) Upper Layers
ATM Adaptation Layer
ATM Layer
Physical Layer
CS sublayer
TC sublayer
SAR sublayer
PMD sublayer
(b) Describe, with the aid of a timing diagram, the exchange of transport protocol units (TPDU's) which occur when establishing a class 4 transport layer connection and hence define the term THREE WAY HANDSHAKE. [4]
(c) Explain how the use of a three-way handshake can eliminate the problem of the sending station crashing having just requested a transport connection. [4]
(d) Justify the use of a serving address by the transport layer and explain the operation of the procedure which is used to provide a serving address. [8]
(b) Describe how the effects of loading can be taken into account by a router when measuring line cost. Discuss whether including the effects of loading when calculating new routes can be guaranteed to produce optimal steady state network performance for stable traffic patterns. [8]
(c) The link state packets for a particular network are shown in Figure Q5. Find the shortest route to node D from node A using the link state packets and thereby identify the outgoing link for packets to node D. [4]
(d) Sketch the topology of the network corresponding to the link state packets shown in Figure Q5. [4]
Figure Q
B Seq Age A 7 C 8 F 1
D Seq Age C 5 F 4
A Seq Age B 7 E 3
E Seq Age A 3 C 6 F 2
C Seq Age B 8 D 5 E 6
F Seq Age B 1 D 4 E 2
A monitor process, an inventory process and a maintenance process, the conceptual schema’s of which are given in Figure Q6, are located at different stations linked via a computer network.
m_number: string(1..9); m_name: string(1..80); m_type: string(1..15); m_location: string(1..80); cyc_done: integer; m_status: machine_state; m_part: part; on_hand: integer;
Monitor Process Conceptual Schema
m_number: string(1..9); m_name: string(1..80); m_type: string(1..15); m_location: string(1..80); m_cost: float; supplier_name: string(1..80); supplier_phone: string(1..10);
Inventory Process Conceptual Schema
m_name: string(1..80); m_location: string(1..80); last_maint: string(1..6); next_maint: string(1..6);
Maintenance Process Conceptual Schema Figure Q
(b) Explain, with reasons, whether or not it is possible for the maintenance process and the monitor process to interwork. [4]
(c) Find the application contexts that correspond to communication between each of the processes. [4]
(d) Explain the relationship between an application entity and an application association. [4]
(e) Explain what is meant by the term Application Control Service Element (ACSE) and indicate how it is used in application layer communications. [4]
1 5 a
transmission delay. It may be assumed that the channel propagation delay is 25.6μs. [7]
(b) The network described in part 8(a) is divided into two separate Ethernet segments, each containing 50 nodes, which are joined by a switching hub. Find the average data rate available per node if each segment sends 25% of its messages to the other segment. It may be assumed that the switch is capable of handling the maximum message rates involved. [6]
(c) For the network described in part 8(a) if each of the 100 nodes produces the following loading over a 5 minute period: 1x 1 Mbyte file; 2x 2 Mbyte file; 1x 6 kbyte email. Find the load offered to the local area network and comment on which, if any, of the configurations in parts (a) or (b) would provide satisfactory operation. [7]
