Download pdf - fundamentals of telecommunication excercises

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Exercise no. 1

As a new service provider, you plan to deploy a telecommunication network with 20 exchange system nodes,

5 of which provide transit functionality only. How many transmission system components do you need to install

within the transport network among the exchange system nodes if …

a … the exchange system nodes are to be interconnected completely meshed?

b … the exchange system nodes are to be interconnected in a ring structure?

c … the transit nodes are to be interconnected completely meshed and the remaining exchange nodes are arranged

in 5 independent rings, each of which integrates one of the transit nodes (providing all rings comprise the same

number of exchange nodes)?

d Which of these network structures is beneficial regarding service availability, which is beneficial regarding system

acquisition costs?

e Which of these networks structures would you deploy, and why?

Fundamentals of Telecommunication: Exercises 1

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Exercise no. 2

The telecommunication network shown below consists of 2 PCs, 1 ISDN exchange system, 1 POP (Point Of

Presence) and 1 router connected to a LAN. The PCs communicate via IP data packets.

a Identify the multiplexing mechanisms applicable to the following systems as shown in the figure above (multiple

answers possible).

PC at LAN • STD, • Space Division Multiplex, • Wavelength Division Multiplex, •

• Frequency Division Multiplex, • ATD with variable block length, •

• ATD with constant block length, • Code Division Multiplex

ISDN Exch. • STD, • Space Division Multiplex, • Wavelength Division Multiplex, •

• Frequency Division Multiplex, ATD with variable block length, •


b Identify the connection concepts applicable to the following systems as shown in the figure above.

IP Router • • Connection-oriented communication,

• • Connectionless communication

POP • • Connection-oriented communication,


c Identify the switching/routing principles applicable to the following systems as shown in the figure above.

ISDN Exch. • • Circuit switching,

• • Packet switching

IP Router • • Circuit switching,

• • Packet switching

IP

Router

ISDN

Exchange POP

ISDN ISDN Internet LAN


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Grundlagen der Telekommunikation Informationsübertragung II

3

Ethernet-

LAN 2

PC 1

PC 2

PC 3

IP-

Router

1

Ethernet-

Switch

a

b

d

c

e

Ethernet-

LAN 1

IP-

Router

2 f

Ethernet-

LAN 4

Ethernet-

LAN 3

DSLAM

IP over ATM over ADSL

Exercise no. 3

a Identify the multiplexing mechanisms applicable to the following systems as shown in the figure above (given that

PCs 1 and 3 exchange a file via IP data packets).

PC 3 • STD, • Space Division Multiplex, • Wavelength Division Multiplex, •



DSLAM • STD, • Space Division Multiplex, • Wavelength Division Multiplex,



b Identify the connection concepts applicable to the following systems as shown in the figure above (given that PC

1 requests a web site hosted by PC 2)

PC 2 • • Connection-oriented communication,


Switch • • Connection-oriented communication,


c PC 1 sends an IP packet to PC 3. Identify all interfaces (a…f) within the figure above, on which a pure Ethernet

frame is sent (assume that both, the Ethernet switch and the IP router are aware of any information required in

order to forward the packet correctly).


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Exercise no. 4

Identify the switching/routing technology/-ies (IP, ATM, or 64 kbit/s) most adequate for the following applications.

Substantiate your decision briefly.

a Voice communication

b Data communication via Internet

c Intermittent sending and receiving of short data packets

d Combined voice and data communication

e Data exchange between branch offices of a major bank

Exercise no. 5

A protocol stack comprises protocols for layers 1 to 4, providing the following frame layouts

(PCI = Protocol Control Information, SDU = Service Data Unit).

- Layer 1 protocol: PCI = 2 Byte, SDU = 98 Byte




Calculate the overhead (in percent) in relation to the overall amount of transferred data.


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Exercise no. 6

You can choose between an IP-based and an ATM-based communication network.

a Which network would you prefer to provide a video conference? Substantiate your decision briefly.

You now continuously transfer media payload packets, each sized 480 Byte.

b Calculate the overhead (in percent) in relation to the overall amount of transferred data if IP technology is used.

c Calculate the overhead (in percent) in relation to the overall amount of transferred data if ATM technology is

used.


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Exercise no. 7

A vending machine (e.g. selling beverages) is given. A coin is already inserted. The machine is deployed as a

Mealy state machine. The state graph is given in the figure below.

The vending machine provides the two conditions C1 and C2. The following 3 input signals are used.

I = Coin inserted

P = Button for product request pressed

M = Button for money return pressed

The following 3 output signals are used.

D = Dispense product

R = Return coin

N = No reaction

Outline an SDL diagram showing the conditions and process flows of this vending machine.

C1 C2

M, R

P, D

I, N

I, R

P, N

M, N


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Exercise no. 8

A L3 protocol instance of a telecommunication equipment is described by the following state table.

Use the given information to develop the corresponding …

a … state diagram.

b … SDL diagram.

State Event/Input

0 1 2 3 4

Start

Start IND / 1

Start REQ

Start / 3

No interest

- / 0

In progress

In progress IND / 4

In progress REQ

In progress / 2

Done

Start CONF / 5

Start RESP

Done / 5


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Exercise no. 9

Assume that your Internet access is provided according to the following figure via an ISDN card in your computer.

a Assign the relevant protocols to every communication segment (1…6), and identify the corresponding OSI

layers. Consider OSI layers 2...4 only.

b Outline a layer model for every network element, also illustrating the interworking between Internet and ISDN

protocols.

IP

Router Server

POP with

IP Router

64kbit/s

ISDN Ex.

1 2 4 5

3

6


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Exercise no. 10

Consider an IP network based on Ethernet II, consisting of 3 host computers (A, B, C), 1 switch and 1 IP router

(see figure below). Communication is based on IPv4. The switch operates on OSI layers 1 and 2 only,

MAC is used for addressing. Ethernet frames received by the switch are forwarded only on the interface

providing a path to the respective destination host. All relevant MAC and IP addresses are given within the figure.

IP

Router

Host A

Host B

Host C

MAC: 00:10:5A:00:00:1A

IP: 192.168.0.10

MAC: 00:10:5A:00:00:1B

IP: 192.168.0.11

MAC: 00:10:5A:00:00:2A

IP: 192.168.1.23

MAC: 00:10:5A:00:00:2B

IP: 192.168.0.1

MAC: 24:20:60:34:67:AF

IP: 192.168.1.1

Switch

100

Base-TX

100

Base-TX

100

Base-TX

100

Base-TX

1

2

3

4


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To exercise no. 10

a Host A sends an IP packet to host B. Outline the Ethernet frames sent on interfaces 1, 2, 3, and 4 by

specifying source and destination addresses for both, MAC and IP according to the following frame structure.

Also annotate unused interfaces.

b Host A sends an IP packet to host C. Outline the Ethernet frame sent on interface no. 3 by specifying source

and destination addresses for both, MAC and IP according to the frame structure shown above.

MAC source

address

MAC dest.

address

IP source

address

IP destination

address


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Exercise no. 11

Assume an IP network as shown below, used for communication by computers A and B.

Consider the following MTU values: Sub Networks 1 and 4: each 532 Byte; Sub Networks 2 and 3: each 276 Byte.

An application on Computer A sends IP packets each sized 1024 Byte, a header of 20 Byte is generally assumed.

Outline the respective IP packets as carried on Sub Networks 1…4, considering ID, M, FO, and payload.

Exercise no. 12

A TCP message contains 1964 Byte payload data and a 20 Byte TCP header. It is passed to IP for delivery over

the Internet. The message is forwarded from the source host through 2 different networks (i.e. via 1 router) to the

destination host.

The L1/L2 protocol used in the first network adds a 12 Byte header and provides an MTU of 1024 Byte.

The L1/L2 protocol used in the second network adds an 8 Byte header and provides an MTU of 524 Byte.

Note that the MTU specifies the maximum total size of a packet being sent through a respective network,

including L1/L2 headers.

Specify size and offset of the fragments delivered to the destination host‘s network layer. Assume minimum header

size for all IP headers.

IP

Router

1

IP

Router

2

IP

Router

3 Sub Network 1 Sub Network 2 Sub Network 3 Sub Network 4

Computer A Computer B


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12

Exercise no. 13

While migrating from IPv4 to IPv6 networks the following Ethernet frame has been captured.

Additional information not provided in the figure: Only 14 Byte Ethernet II overhead (originally: 26 Byte) are displayed.

12 Byte additional Ethernet overhead have to be considered within this exercise.


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13

To exercise no. 13

a Specify the protocol stack for frame 2. Provide both, protocol names and OSI layer numbers.

b Calculate the overhead (in percent) of Ethernet II frame 2 in relation to the overall amount of transferred data,

if the ICMP protocol data are completely considered as payload.

c Complete the fields of the IPv6 packet shown within the following figure, using the information provided for frame

2. State additionally the size of the IPv6 header in Byte.

d What happens to the IPv6 packets within the considered network according to the information provided in the

figure above?


Data

32 bit

H e a d e r

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Exercise no. 14

The routing table of an IP router contains entries as given in the table below. The router routes IP packets

directly to hosts via interface 0, or the packets are forwarded to routers R1 or R2, respectively.

Describe how the considered router treats IP packets addressed to the following destinations:

a 128.96.39.10

b 128.96.39.151

c 192.4.153.17

Network destination Network mask Next router

128.96.39.0 255.255.255.0 Interface 0

128.96.39.128 255.255.255.128 R1

Default R2


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Exercise no. 15

Describe briefly the TCP communication shown in the below MSC (Message Sequence Chart).

Which phase of a TCP connection is shown here?

A B

1

2

3

4

5

6


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16

Exercise no. 16

An MSC of a TCP communication is shown below. The TCP packets exchanged are numbered sequencially.

Provided flag names indicate that the respective flags are set (e.g. [ACK] ACK flag = 1 etc.).

Sequence and Acknowledgement numbers are provided behind „Seq:“ and „Ack:“, respectively.

If applicable, the size of the payload contained within a packet is provided behind „Data:“

Complete sequence and acknowledgement numbers of TCP packets 4…11 within the figure.
