Title: Indicative Content 1.1: Introduction of common terms used in local area network

Topic 1: Introduction of common terms used in local area network

A. Definition of LAN

Local area networks (LANs) are computer networks ranging in size from a few computers in a single office to hundreds or even thousands of devices spread across several buildings. They function to link computers together and provide shared access to printers, file servers, and other services

[Image: LAN]

Image Source: Internet

B. Common terms used in Local Area network

Computer network: Computer network is a group of computers that shares information across wireless or wired technology likewise network is a collection of computers and devices connected together, often wirelessly, via communications devices and transmission media.

The internet: Internet the term internet (dived into two word INTER and NET short for International Network) is a worldwide collection of networks linked together. It is also largest wide area network in the world.

The functions of internet

- Communication and Access information
- Downloading program, document and video
- Participate in discussion
- Online shopping
- Online advertising
- Money transfer

- Internet service Provider (ISP): Internet service provider is a company that supplies or provides internet services to the client and hosting. Some of the factors considered when choosing internet service provider: Services offered, cost internet access, types of communication, security, speed and technical support.
- Firewall: Firewall is a system designed to prevent unauthorized access to or from a private network.You can implement a firewall in either hardware or software form, or a combination of both differ to antivirus which is software detect, scan and prevent virus from computer. Firewalls prevent unauthorized internet users from accessing private networks connected to theinternet, especially intranets.

The difference between Firewall and Antivirus

[Image: Table]

IP address: Internet Protocol address is 32 bits logical address assigned to network interface cardthat help computers to communicate.

TCP/IP: is the language a computer uses to access the internet. It consists of a suite of protocolsdesigned to establish a network of networks to provide a host with access to the internet.

The Benefits of using TCP/IP

- Good failure recovery.
- The ability to add networks without interrupting existing services.
- High error-rate handling.
- Platform independence.
- Low data overhead.

DHCP: is a protocol for assigning dynamic IP addresses to devices on a network. With dynamic addressing, a device can have a different IP address every time it connects to the network means that Dynamic IP changes each time when a user connects to a network.

While The static IP address is fixed IP address which is manually assigned to a device for a long period of time. is a network management protocol used on Internet Protocol networks whereby a DHCP server dynamically assigns an IP address and other network configuration parameters to each device on a network so they can communicate with other IP networks.

Dynamic Host Configuration Protocol (DHCP) is anapplication layer protocol used to distribute network configuration parameters, such as IP addresses, subnet masks, default gateways, etc. to hosts on a TCP/IP network. Assigning network parameters using DHCP reduces the amount of work of a network administrator, since there is no need to statically configure parameters on each device.

Advantages of Dynamic Host Configuration protocol

- Automatic management of IP addresses, including the prevention of duplicate IP address problems
- There is no need to manually configure each client with an IP address.
- You don't need to keep a record of the IP addresses that you have assigned
- You can automatically assign a new IP address if you move a client to a different subnet.
- Address duplication is eliminated as DHCP automatically tracks IP address assignments.
- The DHCP server can detect unauthorized DHCP servers on the network

[Image: DHCP]

Source: Internet

1. DHCP DISCOVER: IP Address request
2. DHCPOFFER: IP Address Offer
3. DHCP Request: IP address selection
4. DHCPACK: IP address Acknowledgement

DHCP Discovery: when we start a device, it checks whether a valid IP is available or not. If the valid IP configuration is not available, the device generate a special messages known as the DHCPDISCOVER message and Broadcasts this message on the local LAN segment.

To broadcast CHCPDISCOVER messages, the device uses the 0.0.0.0 and 255.255.255.0 as the source address and destination addresses, respectively. The 0.0.0.0 and 255.255.255.0 are two special addresses. Any device, whether it has a valid IP configuration or not, can use these addresses to send local broadcast messages. From these addresses, the 0.0.0.0 is used as the source address. If a device does not have the source address, it can use this address to send broadcast messages.

255.255.255.0 Is the local broadcast address. Any message sent on this address is received by all hosts of the local network.

DHCP Offer: since the client sends the DHCPDISCOVER Message to the local broadcast address, if a DHCP Server is configured on the local network, it will also receive the message. If multiple DHCP Servers are configured on the Local network, they all will receive the DHCPDISCOVER message. If multiple DHCP Servers are available, based on their configuration, one of them or all of them can reply to the DHCPDISCOVER message. In the reply to the DHCPDISCOVER message, a DHCP Server sends a DHCPOFFER message to the client.

Since the client does not have an IP address the DHCP Server can not send the DHCPOFFER message directly to the client. Because of this, the server sets the destination address to 255.255.255.255. In other words the server broadcast also broadcasts the DHCPOFFER message to the local network.

The DHCPOFFER message contains protocol specific information and an IP configuration. An IPconfiguration typically include the following important information: the IP address for the client, the subnet mask of the proposed IP address, the address of the default gateway, the DNS domain name, the DNS server address or addresses and the TFTP server address or addresses.

A part from these, the DHCPOFFER message also contains other protocol specific information such as the lease duration and client ID. This information is required by the core functions of DHCP.

DHCP Request all host in the local network receive the DHCPOFFER message. The host that sent the DHCPDISCOVER message accepts the DHCPOFFER message. Except the original host, all other hostsignore the DHCPOFFER.

DHCPACK the DHCPACK indicates that the server “Acknowledges” the request and the DHCPACK message contains the field which indicates the IP address lease time, and network configuration parameters that the client is being configured with. The DHCPACK message is an acknowledgement to the client indicating that the DHCP server has received the DHCP Request message of the client, and the client can use the offered IP configuration.

- Automatic Private IP Address (APIPA) is the window function that provides the DHCP auto configuration addressing. APIPA assigns a class B IP address from 169.254.0.0 to 169.254.255.255 to the client when a DHCP server is either permanently or temporarily unavailable.
- Mac Address: MAC Address (Media access Control) address is 48bits hardware or physical address of LAN Card (NIC).MAC is usually stored in ROM on the network adapter card by manufacture and it unique. MAC address is also known as physical address, hardware address and burned-in address. MAC addresses are usually written in the form of 12 hexadecimal digits. For example, this is a valid MAC address: D8-D3-85-EA-1B-EE. Each hexadecimal character is 4 bits long, so the first sixhexadecimal characters represent the vendor (in this case, Hewlett Packard).

C. The Purpose of Local Area Network

- To share the files

A network offers the facility of sharing a file so that it may be used by other users. The owner of the file may set permissions so that other users may be limited on the way they use that file. To those
who are given read/write will be able to modify the content of the file.

- To share information

Computer networks provide communication possibilities faster than other facilities. Because of these optimal information and communication possibilities, computer networks may increase the organizational learning rate, which many authors declare as the only fundamental advantage in competition.

- To share Printer

If you have a printer attached to your computer, you can share it with anyone on the same network.It doesn't matter what type of printer it is, as long as the printer is installed on your computer and directly attached with a universal serial bus (USB) cable or other type of printer cable. Whoever you choose to share the printer with will be able to use it to print, provided they can locate your computer on the network.

- To communicate (Sending and Receiving message)

Communication begins with a message, or information, that must be sent from one individual or device to another. People exchange ideas using many different communication methods

Disadvantages of Local Area Network

1. Cabling can be expensive to install and replace.
2. A fault with the server will prevent the whole network from working.
3. Security measures are needed to restrict access to the network (insecurity).
4. WANs are vulnerable to hackers and viruses.

Topic 2: Types of Lan

Types of Local Area Network

[Image: Types of Lan]

Source: Internet

1. Client-server LAN

In a client-server LAN environment, a single server connects to multiple devices known as clients. Client devices cannot interact with each other and a centralized machine handles activities like network traffic management, network access control, etc. This LAN type may be faster in small perimeters, but in a large perimeter, it places too much pressure on the central server.

2. Peer to peer (P2P) LAN

In a P2P LAN, there is no centralized server, and all connected devices have access to each other, regardless of whether they are servers or clients. The advantage of a P2P LAN is that devices can freely exchange data with one another, making it easier to stream media, send files, and perform similar data exchange activities. On the downside, they tend to be less powerful than client-server LANs.

3. Token ring LAN

Based on the architecture design, you can classify LANs into a token ring or token bus categories. In the former, all devices are arranged in a ring when they are connected. A token is assigned to every connected device based on its requirements. It was introduced by IBM in 1984 for use in corporate environments when ethernet technology was still in the early stages of development.

4. Token bus LAN

In a token bus LAN, connected nodes are arranged in a tree-like topology, and tokens are transferred either left or right. Typically, it provides better bandwidth capacities than a token ring LAN environment.

5. Wired LAN

Wired LAN is probably the most common LAN type in use today. It uses electronic waves to transfer data across optical fiber (or cable variants) instead of tokens. Wired LAN is extremely reliable and can be very fast, depending on the performance of the central server. However, it can hinder portability and flexibility, particularly in environments with no fixed number of devices.

6. Wireless LAN

Wireless LAN is commonly used in home environments to connect computing devices, wearables, smart appliances, etc. but there is a massive enterprise market for wireless LAN as well, growing by 10.3% year over year as per IDC. This type of LAN uses radiofrequency for data transfers, which can make it susceptible to security risks. It is also battery-intensive and may show fluctuating performance depending on where the wireless device is situated.

7. Cloud-managed LAN

Cloud-managed LAN is a specific type of wireless LAN where a centralized cloud platform is used to manage network provisioning, policy enforcement, access control, and other aspects of network performance and security. In a heterogeneous networked environment, cloud-managed LAN streamlines governance, making it a good fit for enterprise use. By 2025, cloud-managed LAN will be worth over $1.18 billion globally, as per research by Market Research Future.

Topic 3: Key architectural components of LAN

What is the architecture of LAN?

LAN architecture is the set of rules and design principles that define the LAN. A LAN is made up of three components: physical media, such as the cabling and network interfaces; the topology, such as a star or ring topology; and the protocols, or LAN technologies, such as Token Ring or Ethernet

Components of LAN are :

- PCs/workstations and servers.
- Network Interface Card (NIC)
- Cabling and connectors, for example, coaxial cable and BNC connector, Unshielded Twisted Pair (UTP) and RJ-45 connector.
- Hub, concentrator, and more complicated network devices such as Bridge, LAN Switch and Router.

Key components of Lan architecture

[Image: Components of LAN]

Image Source: Internet

I.C 1.1 Assessment

Introduction of common terms used in local area network

Definition

Q: 1. The internet is defined as Networks of network
A: true

Definition

Q: 2. Choose the best answer

DHCP:
- is a protocol for assigning dynamic IP addresses to devices on a network (correct) (Incorrect)
- Is a protocol for assigning the static Ip addresses to device for a network (Incorrect, Try again)