Question

Question 1

(a) Describe the five IP addressing classes. Provide an example for each of classes in binary and dotted-decimal representation.

(b) Show the conversion of each of the addresses.

(c) Describe the function of the subnet address for each of the classes and how does it work. [20 Marks]

Question 2

(a) Define message switching, circuit switching and packet switching. Draw a diagram for each method to show the difference between them.

(b) Identify the samples of network environment that use each of this switching method.

(c) What are the advantages and disadvantages?

Question 3

(a) Write a simple program to create three processes using fork() commands. Use any THREE (3) of the six system calls to show how each child process executes new subprograms using exec’s minions.

(b) Show the output of each of the child process with different data samples. [20 Marks]

Question 4

(a) Compare the bus topology and the star topology. Draw a complete diagram for any given environment for each of the LAN topology.

(b) Using your own assumptions and scenario for each topology to illustrate the concept. Provide the details requirements including the hardware and infrastructure to set-up the proposed solution. [20 Marks]

Question 5

(a) Write a simple program in your Linux environment using C++ to identify PID, PPID and GID for the processes created in Question 3 and display the real and effective user ID. [12 Marks] (b) Modify the program you wrote for Question 3 and include the alarm system call to kill one of the processes that you had created in 30 second.

Answer 1

Question 1 (a) 5. IP_Addressing classes are as follows: 1 Class A © Class B © Class ② Class D 6 Class E Lo class Ali In_Class A IP address, the finest bit is always Q and the first byte is between 0 -127 Tol 107 I bit Host Nlw id id 8 २५ 532 bit bit 8 2 24 324 → 128 Nw id → begin from 0 27 is used 16 m. Host id iddress 00000000 IP addresses teange | ܘ ܘ ܘ ܘ ܘ G 0.0.0.0 to 127 187, 255.255.255 • this class IP address is used for very big network Company example, like Nasa

@ Class B : In Class B IP adolmessg the first 2 bits is 10 & fist first byte is between 128 - 1941 10 2 32 bits i ell? 2 bit already 14 2 Nλω id 216 Host id *** 216 216 Selected 214 1. IP address_Range 10 000 000 +0 - 128 0 0 0 0 01111 129 128.0lce "to 191,255.255.255 I 01 +63 → 191 • This Class IP address is used for a Basic Medium network like multinational companies. ③ I Class C 00 + In_class 6, IP address, the_first 2 bits axet & third bit is o i.e. 110 llo 000 2 २० NW id Host id 24-3 21 = 22

Ule Loo 0 0+0-19.2 ooee I +1 -19 3. IP addresses Range + 192.0.0.0 to 223:255.255.255 1+ 32 -> 224 This Class_is_used for e amall network such as Small companies of colleges Class 0. . Ih Class D IP address, the first 3 bits acé 111 and 4th bit is a ie: JILO Duilo There is no seguegation of host and network addresses. 32 2. 611100000-0+124 @ 0001-14925 IP address Range 4 224.0.0.0 to 239.255,255,255 1110111 239 • It allows multicasti which means a dataguam directed to multiple hosts.

Classe: The class IP address begins with 11 and List byte is between 240 - 255 11110000 - 200 -241 IP address Range 240.0.0.0 1111 255 255.255.255.2557 • It is Reserved for future: use, denelopment. purpose_&_ Hesearch. Examples 000000001 00001011 0000101L 0101111 1!! bil isee. tis is class A 09.14,23, 120.3 fix at byte is 14 (between 0 - 127) the class is a © 110 00001 10000011 00011041 illllllll Hugt 2bits ovel the third bil iso this is a close adducas.

c) Bubnell If an Ouganization was guanted lange block un class_À_ou B, it could divide the addresses into severcu_canliguaus.guoups and assign small networks. Called loubnets) Subnetting uncreases the number of t's in the mask The Subnet mechanism used a portion of the Host_1D field to identify individual. Subnets. Begmentation subnet 172.16.2.15 A 1.72.16.6.0 172.16.2.0 toruto 172.1 bello this D 3 192.16.3.0 U B

Question 2):

Switched communication networks are those in which the data transmitted between various intermediate nodes is routed from source to destination. Switching is the technique by which nodes monitor or transfer data between different points on a network to transmit it. There are three switching methods:

1) message Switching :

End-users communicate in message switching by sending and receiving messages which included all the data to be exchanged.Messages are the tiniest single unit. Not directly linking the sender and the receiver. There are multiple intermediate data transfer nodes to ensure the message reaches its destination. Data networks converted to messages are thus called hop-by - hop systems.

message switching has two important characteristics: 1) store and forword: A store-and-forward switch can forward a message only when there are ample resources available and data is acknowledged by the next hop. 2) message delivery: This bundles all of the information in a single message and moves it to the destination node from source. Message must have a header containing the information about routing the message, including the source and destination.

Advantages:

As message switching can store message for which communication channel is not accessible, it helps to minimize network traffic congestion. In message switching, the network devices share the data channels. This makes traffic control effective by prioritising the messages.

Disadvantages:

In message switching, message needs to be stored which requires a large storage capacity for any intermediate device in the network. Message switching can not be used for applications in real time, since storing messages causes delay.

2) circuit Switching:

circuit switching is connection oriented i.e. a physical path between the sender and receiver of the message before a message is delivered. and initially it is designed for voice communication. Inflexible, since all parts of a transmission follow the same path once a direction is set. Once the message is sent to the receiver, the source tells the network about the transmission completion and all the switches issued. The link and other connecting devices are then used to set up a different connection. Circuit switching is always implemented at the Physical Layer.

Circuit Switching can be implemented using two technologies :

1) Space Division Switching

2) Time Division Switching.

advantages:

The main benefit of circuit switching is the establishment between the computers of a committed transmission channel which gives a guaranteed data rate. There is no delay in data flow in circuit switching because of the dedicated transmission path.

Disadvantage:

Establishing relations takes a long time. When setting Minimal delay in transmission.p dedicated channels more bandwidth is needed. It can not be used to transmit any other data, even if the channel is free as the circuit switching link is dedicated.

3) packet Switching:

PAcket Switching is connectionless, because no physical link is formed before the transmission begins. This is divided into some manageable bits, called packets, in packet switching before the message is transmitted. Those packets are routed from source to destination one by one. Packet Swapping uses the technique of Store and Forward when swapping the packets; every hop first stores the packet and then forwardes it.

advantages:

Less effective in terms of bandwidth, because the reservation circuit idea isn't there. Minimal delay in transmission. More tolerant of fault because packets that follow different paths, unlike Circuit Switching, if any connection is down.

disadvantages:

Packet Switching don’t give packets in order, whereas Circuit Switching provides ordered delivery of packets because all the packets follow the same path.
Since the packets are unordered, we need to provide sequence numbers to each packet.
Complexity is more at each node because of the facility to follow multiple path.
Transmission delay is more because of rerouting.