A network that will connect several computers lab will have several network devices in order to ensure the connectivity in the network working. The devices that will be in the network are:
– Nodes are the PCs that are connected to the network. This is because the nodes will have the software and programs that will ensure the network is working. The nodes will allow the user to perform certain task ie printing via the network.
– Hub is a component which acts as a convergence point of a Network allowing the transfer of data packets. In its simplest form a hub works by duplicating the data packets received via one Port and making it available to all ports, therefore allowing data sharing between all devices connected to the hub.
Hub will receive the data packets from the switch before its transferred to the destination ie. the nodes. It also allows data sharing among the nodes as all nodes and devices are connected to the same hub.
3. Network Interface Card (NIC)
– Network interface card is a device that attached to the nodes that allow the network cable to be connected from the hub to the nodes. It also known as network card, network adapter, network interface controller (NIC)or LAN adapter. It was designed to allow computers to communicate over a computer network. It will be attached to the nodes motherboard.
– Switch is a device that channels incoming data from any of multiple input ports to the specific output port that will take the data toward its intended destination. In the above sketch, switch will transfer the packet data to the intended hub before the packet is distributed to the dedicated nodes. Although in the above sketch, hub were also been use, switch is still in use as switch capable of inspecting data packets as they are received, determining the source and destination device of each packet, and forwarding them appropriately ie to the respective hubs. In Open Systems Interconnection (OSI) model, a switch performs the layer 2 or Data-Link function.
5. Network cable
Network cable is very important in a network unless the network setup was made wireless. There are many types of network cables. The most used type of network cable is the unshielded twisted pair and the coaxial. The network cable will transport the packet data received or sent by the nodes. Today, the fibre-optic type of network cable is quite popular. The criterion to choose the cable is based on the network topology used in the network.
Modem is a combination of modulate and demodulate. Modem will modulate the analogue data received and encode it to digital so that the computer/nodes can read the data received. It enables a computer to transmit data over, for example, telephone or cable lines as the information stored in the computer is in digital form. The transmission of data via cable lines is in analogue waves. The modem will convert the data receives from the computer before it allow the data to pass through the cable lines. The modem also will convert the data received in analogue waves before the data receives by the computer.
The server act as the ‘gatekeeper’ to the network. It will determine the protocol to be used by the nodes in order to connect to the internet. In the server itself, firewall will be setup and anti virus programs will be installed so that all data packets send and receive will be free from any virus that could harm the network.
Question 1 B
Network management system (NMS) is a combination of software, hardware and procedure that manage, monitor and administer a network. Network administrator will take the take charge of the NMS of the organization. NMS give wide coverage of the network including:
1. Reliability – NMS will ensure that the network is available to use for the user. By adopting NMS approach, every hardware and software malfunctions can be respond and detected.
2. Security – NMS will protect the network from unauthorised users. Only authorised/registered user is allowed to use the network. Registered user maybe supplied with dedicated password or dedicated proxy server number in order to use the network.
3. Performance – NMS will ensure the traffic flow of the network run smoothly. It will eliminate all the bottlenecks in the network by setting up priority of data flow.
4. Bandwidth management – By adopting NMS, it can help controlling the communications (traffic, packets) on a network link, to avoid filling the link to capacity or overfilling the link, which would result in network congestion and poor performance.
Examples of NMS are:
1. OpenNMS – it is an open source network monitoring platform. It was mainly written on JAVA and operating systems such as Windows, Linux and Sun solaris does support this NMS. This OpenNMS focuses on three areas which are the service polling, data collection, and event management.
2. Just For Fun NMS (JFFNMS) – it was designed to monitor a simple network management protocol (SNMP). Basically SNMP is a set of protocols that manage a set of complex network. JFFNMS was written on PHP which can be run on LINUX and Windows. This JFFNMS focuses on:
1. Status Map, gives you a quick look of your network
2. Events Console – one dashboard that will shows all kinds of events in one screen
3. Performance Graphs – display of the network performance interactively
4. Database Backend
Question 1 C
The OSI model defines all the methods and protocols that are needed to connect one computer to another one via a network. Each layer have different functions and are relies on the functions of the lower level layer. The function of each layers are listed below:
1. Physical – it define the properties of the physical medium used to make the network connection. It conveys the bits stream on the physical hardware. Network Interface Card, hub and cable are the example part of physical layer.
2. Data Link – it responsible to transfer the data between the end of a physical link. It will ensure a reliable data stream by including error detection, framing and flow control. The data element carried by the data link layer called as FRAMES. Example of data link layer are frame layer, ATM and token ring.
3. Network – Network layer defines how data packets travel from one point to another point via a network. It responsible to route and to switch the data to dedicated destination in order to establish transparent delivery of data. This network layer also known as packet layer. Internet Protocol (IP) and Internet Protocol Exchange (IPX) are the example of protocols under the network layer.
4. Transport – It manages the flow of error-free information from one point to another point. It will segment the data receives from session layer into smaller packet if necessary and pass it to the network layer. It will also ensure that all the data packets are encoded and sequence properly. It will also identify each and every computer in the networks uniquely. TCP and UDP are some examples of transport layer.
5. Session – this layer refers to the connection between nodes to a network server. Communication between computers is established, maintained and terminated by the session layer. Session layer will coordinate the communication process between nodes. It will also enforce the rules of the dialog for example half or full duplex communication. Telnet and AppleTalk are the example.
6. Presentation – it will determine the formats of data, translation , encryption and data compression. It will decode the data receive from the sender and encode to the receiver so that the message can be understood. Example are JPEG,GIF, XLS.
7. Application – this layer will control the operating system and the application on how to interact with the network. It consist the protocols that define specific user-oriented application such as email and file transfer. Example of this layer is the Telnet, FTP and Windows Client.
The TCP/IP layer is different with the OSI layer as the TCP/IP only consists of four layers. Each layers function is a listed below.
1. Network Access – it connect a host to the network hardware. It places the data into frames. This layer performs all the functions of the first two layers in OSI.
2. Internet – also known as internetworking. It is the core of Internet Protocol (IP). It responsible is to transfer the data/message from the source to the dedicated destination. The destination may be set by the IP address or the subnet address.
3. Transport – It can be define by 2 protocols which are the User Datagram Protocol (UDP) and the Transmission Control Protocol (TCP). It provides data flow for the application layer. It will transfer the data to the application layer.
4. Application – it is similar to the OSI application layer. It acts as the communication interface for the user to use the network. Example e-mail, file transfer, telnet & ftp.
Both OSI and TCP/IP used the layer approach in both model. This is because by using layers, the data sent through the network is much secure. This was due to that the data is encrypted at each stage so that the reliability of the data is secured.
The designing of the network is much easier by using the layer approach. This is because layer approach enables each layer to be completely independent from each other. This will allow the developer to change the layer’s functions easily without affecting other layers.
Question 1 D
Wireless LAN is one of the technologies that allow or enable devices such handphones or PDA to connect with other devices wirelessly. Although it is a wireless connection, it still require a physical medium that will transmit the signals to pass. However, instead using cables such as twister pair or fibre optic, wireless LAN (WLAN) use infrared light or radio frequencies. The usage of radio frequencies is much popular now as it covers longer range and bigger bandwidth.
The other technology that allows wireless connection between devices is the Bluetooth technology enables devices such as handphones or PDAs to connect with other mobile devices in a limited area. It is a wireless connection. Both devices that want to be connected must have the Bluetooth feature in each device. Bluetooth connections only connect devices that have the Bluetooth capability. Nowadays also all mobile phone and laptops are equipped with Bluetooth technology.
Bluetooth technology relies on two things, a radio frequency technology and the protocol software enabling it to transmit data to other devices. Bluetooth-capable devices can transmit data to other devices not within the line of sight of the user.
The Bluetooth technology was invented by Ericsson somewhere in 1990’s. The Bluetooth technology uses the radio frequency of 2.45 GHz and can connects all the devices in and transmit the information within 33 feet radius.
Question 2 A
i. Subnet is a short form of subnetwork. It is a process to break a large network to several sub-network. It modifies a single IP network to two or more logically visible sub-sections. Subnetting usually used when a network number needs to be distributed across multiple LAN segments.
IPv4 is internet protocol version 4. It was the 4th revised version of development of internet protocol. IPv4 address be divided into 5 classes namely class A, B, C, D & E. However, this assignment will cover only class A, B, and C.
Class A Address: If the bit is 0 to 0, the address will begin with a decimal point ranging from 0 – 127. Valid host IP address will be range from 126.96.36.199 -188.8.131.52. It has 8 number of bits in the network address. Example IP no of class A address is 10.10.9.201. Class A usually use for very large network. The first octet of this class is always 0. Eg 115 = 01110011
Class B Address: If the first two bits are 10, the address will begin with a decimal point ranging from 128 – 191. Valid host IP address will be range from 184.108.40.206 – 220.127.116.11. It has 8 number of bits in the network address. Example IP no of class B address is 18.104.22.168. Class A usually use for medium-sized network. It will have the first bit value of 1 and second bit value of 0 in the first octet. Eg 145 = 10010001
Class C Address: If the first two bits are 110, the address will begin with a decimal point ranging from 192 – 223. Valid host IP address will be range from 22.214.171.124 – 126.96.36.199. It has 8 number of bits in the network address. Example IP no of class C address is 188.8.131.52. Class C usually use for small to medium-sized network. It will have the first bit value of 1 and second bit value of 1 and the third bit value of 0 in the first octet. Eg 195 = 11000011
ii. Default subnet mask = 255.255.255.0
broadcast address= 192.168.1.255
if 6 host per subnet:
2 power of x => 6 , therefore 2 power of 3 = 8, which is greater then 6 hosts.
Mean 3 bits from right bits is for host, 0000 0111
When 3 bits is for host, remain of 5 bits left is for subnet.
Which is 1111 1000
To find how many subnet in the network;
1111 1000, so 2 power of 5(bits) = 32 subnets
To find how many host per subnet ;
2 power of 3 (bits) = 8 hosts
valid host 8 – 2 = 6 hosts
New subnet mask = 255.255.255.248
Network address = 192.168.1.0
Therefore 32 subnets, each with 6 hosts
To find range 1111 1111 – 1111 1000 = 0000 0111 or 256 – 248 = 8
network address valid host broadcast address
192.168.1.0 192.168.1.1 – 192.168.1.6 192.168.1.7
192.168.1.8 192.168.1.9 – 192.168.1.14 192.168.1.15
192.168.1.16 192.168.1.17 – 192.168.1.22 192.168.1.23
192.168.1.24 192.168.1.25 – 192.168.1.30 192.168.1.31
192.168.1.248 192.168.1.249 – 192.168.1.254 192.168.1.255
Question 2 B
i. The operating systems that were used in the network are Windows and Mac. The best protocol to be used is TCP/IP since most all operating system supports TCP/IP protocol. TCP/IP protocol is also a versatile protocol that supports global connectivity without regard to operating system.
ii. Router is the equipment that can connect different protocols is a network. Router is a device that carries the data packets along networks. A router is connected to at least two networks. The router operated in layer 3 of OSI Model which is the network layer. Network layer defines how data packets travel from one point to another point via a network. It responsible to route and to switch the data to dedicated destination in order to establish transparent delivery of data. This network layer also known as packet layer. Internet Protocol (IP) and Internet Protocol Exchange (IPX) are the example of protocols under the network layer.
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