Computer Network Lecture 4 PDF

# Computer Network ## What is a computer network? - It's more than just computers. - Communication devices or electronic devices. - A group of electronic devices connected together to communicate and share information and resources. - **Examples:** A printer, a storage memory (an example of cloud...

# Computer Network ## What is a computer network? - It's more than just computers. - Communication devices or electronic devices. - A group of electronic devices connected together to communicate and share information and resources. - **Examples:** A printer, a storage memory (an example of cloud computing or online memory). - Cloud computing uses a network system but it is not an example of a network. ## Networks explained in the book (page 48) - Networks are connected in various different ways (either wireless or wired). ## Advantages of Cloud Computing: - Larger storage space. - No need for maintenance, if something happens to the computer, it won't happen to the data. - The biggest disadvantage is the security. ## Characteristics of a computer network: - It allows sharing of resources and information. - You can create, save and store files on a computer. - You can connect to other devices (like printers) via one computer which is part of the network; other computers can use the same resources. - Any computer connected to a network is called a node. - A host is a more powerful device that can manage and control all other devices on the network. ## The aims of a computer network: - To minimize the number of resources, and the need for each computer to have all these resources. - Sharing which means that if you need something, you can just type that word. - Communicating between computers. - Sharing hardware and software. ## Firewall - It's located between servers and the internet. - Software - if it's a small network. - Hardware - if it's a larger network with multiple servers. ## Examples of networks: - Social networks. - Mobile networks. - Hospital networks. ## Internet - It's a network of networks. ## Hardware and Software - What do we need for hardware and software to work? - We need hardware, but not software. - We only need hardware components to make this work. - What hardware components are needed? - A network card (located on the motherboard). - **Other hardware components:** - **Routers** - **Modems** - **Distributors** - **Cables** - **HUB** - **Switches** - What's the difference between routers and modems? - What's the difference between HUB and switch? - What does a wireless access point mean? ## Network cables - They are not the standard electric cables. - They are used to connect computers together. - The most popular type is the Category 5 cable. - The connector is called RJ45. - It has 8 pins. ## Network cards - **NIC** (Network Interface Card) or **Network adapter** are both the same thing. - It's an important component, without which the computer won't be able to connect to any network or be part of one. - It supports data transfer. - **There are two types:** - Internal network cards: They're connected to the motherboard (page 152). They have a separate part and can be disconnected via wires. - External network cards: Less common, they can be wireless or USB. - Data transfer is measured in **bandwidths (bits per second, bps).** - An Ethernet card supports a transfer of 10 Mbps and 1 Gbps. ## HTTP,HTTPS and FTP - **http (Hypertext Transfer Protocol)** - protocol for data transfer. - **https (Hypertext Transfer Protocol Secure)** - the same as http but with an added layer of security. - **ftp (File Transfer Protocol)** - protocol for file transfer. ## Mac Address and IP - **Protocol** manages and standardizes data transfer across various forms. - **Mac Address:** it's unique to every device and comes with it. It never changes. - **IP Address:** it changes depending on the network, it's specific to the network. It identifies each device and its location on the network. - What's the difference between address with letters and addresses with numbers? ## Classification of networks - **By network geography:** - **Personal Area Network (PAN):** An example is your phone, tablet, digital camera or laptop connected together. - **Local Area Network (LAN):** An example is a network inside one building, or between buildings that are nearby. It covers a small area. - **Metropolitan Area Network (MAN):** An example is a network connecting computers in a village or city. - **Wide Area Network (WAN):** Connects different countries. - **The Internet is a WAN that connects many smaller WANs together, making all the data and information interoperable.** - **By component roles:** - **Client Server Network:** There is a server that acts as the **main component** of the network. It controls all resources and dictates which client devices can access it. - **Peer to Peer Network:** All devices are equal and have the same access privileges to the same resources. There's no centralized control. ## Topology - **Topology (Structure):** It describes how computers/devices are connected to each other. - **Types of Topologies:** - **Bus Topology:** All devices connect to a single cable called **Trunk.** - **Ring Topology:** All devices connect to form a loop, there is no beginning or end to the network. This could be a single ring or double rings. - **Star Topology:** All devices connect to a central device called **hub** - **Mesh Topology:** Every device is connected to every other device. Internet uses a Mesh topology.