Computer Network
A computer network is a group of two or more computers interconnected via cables or through wireless mode, for sharing hardware and software resources. These resources can be printers, files, CDs, e-mail or any software Interconnected computers are able to exchange information between each Other.
Some examples of a computer network are:
- Computers in a lab are interconnected using a network to share a single printer or software
- Files shared between computers within a building through a computer network
- The Internet
Most of the networks use distributed processing. In distributed processing, particular task is divided among multiple computers (usually a personal computer or workstation) and separate computers are responsible for the different aspects of a process. A successful network needs to meet a number of criteria. Let us discuss these criteria in the following section.
Network Criteria
A network must meet a certain number of criteria. The most important criteria are performance, reliability and security. These criteria are explained below:
Performance: Performance of a network can be measured in many we5 such as transit time and response time. Transit time is the amount of time required for a message to travel from one device to another. Similarly response time is the elapsed time between an inquiry and a response. Furth the performance of a network depends upon a number of factors such the number of users, the type of transmission medium, the capabilities of the connected hardware and the efficiency of software. Performance of a network is evaluated by throughput and delay. Ideally more throughput and less delay is required in a network. Now, if a user sends more data to a network he may increase throughput however, congestion due to increased traffic may result in delay in data transmission in a network.
Reliability: Network reliability is measured by frequency of its failure, the time taken by a link to recover from a failure and its robustness in any catastrophic events.
Security: Network security involves protecting data from unauthorised access and damage. It also includes development and implementation of policies and procedures to recover from data breaches and losses.
Benefits of a Computer Network
A well designed networking system not only saves time, effort but also enables the maximum utilisation of the IT resources. The key benefits of a computer network are:
File Sharing: Users connected to a network can share files, data and access information with each other; without the need to physically move from one computer to another.
Hardware Sharing: Hardware devices such as printer, scanner and CD- ROM drives can be shared by multiple users within a network. Thus, eliminating the need and extra cost of installing separate hardware for individual computers.
Software Sharing: Users can also share software in a computer network and permission to access the software by specific users can also be defined. For instance, the WinZip is installed in a network for ten users however; it is required to be used by only four users. Now, by specifying the sharing permission the WinZip can be accessed by only the four users.
Cost Reduction: Sharing the hardware and the software resources over a network reduces the cost of operations for a business.
Efficient Systems Management: Using a computer network, it is possible to efficiently manage configurations, troubleshoot and maintain the connected computers.
Enables Real-time Communication: A computer network enables real time communication as the Internet can be shared over a network and information can be exchanged through E-mails etc.
Computer network provides multitude of benefits to organisations.
However, a computer network has certain drawbacks. Now lets us q- cuss these drawbacks in the following section.
Drawbacks of a Computer Network
The major drawbacks of a computer network are
High Installation Costs: Installing or setting up, deploying and maintaining a network requires huge cost. Further, trained professionals are required to manage a network, which also involves cost.
Risk of Hacking: A computer network is susceptible to virus attacks and can be hacked. Security procedures and robust firewalls need to be setup to prevent such attacks.
Hardware Damages: The hardware and cable used to set up a network are subject to wear and tear and can hamper the normal functioning of a network.
Network Terminologies
Some of the IT to use in networking are as follows:
Network Nodes: It can be defined as point of connection for transmitting data that can function as an endpoint on a communications network.
Network Device: It is a hardware component used for connecting computers on a network. It links the network to enable communication and controls the data traffic between the network nodes. Bridge, Hub, Switch and Router are some examples of the network devices.
Network Interface: A network interface is a point of connection between a computer and a network. It is basically a component that contains the hardware to connect a computing device to a network.
Network Interface Card: Network Interface Card (NIC) is an electronic circuit card that is required to connect any computer to a network. It controls data communication between the network nodes and the Internet.
MAC Address: It is a computer’s unique 48-bit hardware address assigned to the network interface for data communication at the data link layer. The NIC manufacturer assigns MAC (media access control) addresses into the Local Area Network (LAN) card for wired networks and Wi-Fi card for wireless networks. Ethernet is an example of a wired network and hence, MAC address is also termed as Ethernet address on an Ethernet LAN.
MAC Address Table: The MAC address table is also known as content Addressable Memory (CAM). The MAC address table is used to find out where to forward the traffic on a particular LAN or VLAN. It is used on a switch of the Ethernet.
Table of MAC address
| Details of VLAN | MAC Address | Type | Ports |
| VLAN1 | 001d.80ab.5d60 | Static | FA0/1 |
| VLAN2 | 001e.f724.a150 | Dynamic | FA0/2 |
| VLAN3 | 000e.8316.f14d | static | CPU |
IP Address: IP address is 32-bit address assigned to each node or computer in a Transfer Control Protocol/Internet Protocol (TCP/IP) network. IP address helps in identifying a particular node in a network of nodes for data communication.
Virtual IP Address
Virtual IP (VIP or VIPA) is an IP address that does not correspond to an actual physical network. VIP can be shared among multiple domains or servers. In a virtual IP address host’s dependency on the individual network interface is eliminated. Network Port: A port is a unique number of a network process or application to which, a Web or network message is required to be delivered. It is usually 16 bits in length and represented by decimal numbers. In TCP/IP protocol suite, port numbers are the integers between 0 to 65,535.
Uniform Resource Locator (URL): URL is a Web address assigned to a resource. It specifies the resource’s location on the network of networks. World Wide Web: World Wide Web (WWW) is a database of information on the Internet where Web pages are interconnected with hypertext links.
Network Gateway: A gateway is a network node that connects two networks based on different protocols together. A network gateway can either be hardware, software or a combination of both.
Protocol: Protocol is defined as a set of communication rules required for data transmission over the Internet. Various types of protocols are used for transferring data over the Internet. Some of the important protocols are FTP, Telnet, SNMP, SMTP, FTP, TFTP, NTP, SMB, SIP and POP.
TCP/IP: TCP/IP is a protocol used for data communication over the Internet. TCP is responsible for reliable data transmission over the Intern C. The Internet protocol is responsible for forwarding packet from one computer to another over the Internet.
Network traffic: Network traffic or the data traffic is the amount or data that can be moved over a network in a specific period. Network traffic can be classified as busy or heavy traffic, interactive traffic, latency sensitive traffic and non-real-time traffic. In addition, network traffic also has various properties such as it can be broadcast, multicast and unicast. This will be discussed in subsequent sessions.
