1. Lecture 4 unit 1

2. categories of network A network can be categorized as a 1.Local area network. 2.Wide area network. 3.Metropolitan area network. 4.Personal area network

3. Local area network A LAN is a data communication system within a building, plant, or campus, or between nearby buildings. Its depend on the need of an organization and the type of technology used, a LAN can be simple as two PCs and a printer in someone’s office. It can be extend throughout a company and include audio and video peripherals. LAN size is limited to a few kilometers. LAN are designed to allow resources to be shared between personal computer or workstation. The resource to be shared can include hardware, software or data.

4. An isolated LAN connecting 12 computers to a hub in a closet

5. Wide area network A WAN provide long distance transmission of data, image, audio and video information over large geographic areas that may comprise a state, a country, a continent, or even the whole world. A WAN is a data communication system spanning states, countries, or the whole world. A WAN can be complex as the backbones that connect the internet or as simple as a dial-up line that connect a home computer to the internet. A WAN can contain multiple smaller networks, such as LANs or MANs. The Internet is the best- known example of a public WAN.

6. WANs: a switched WAN and a point-to-point WAN

7. Metropolitan area network. A MAN is a network with a size between a LAN and a WAN. A MAN is a data communication system covering an area the size of a town or city. A MAN is larger than a LAN, which is typically limited to a single building, campus or site. A MAN is often used to connect several LANs together to form a bigger network. When this type of network is specifically designed for a college campus, it is sometimes referred to as a campus area network, or CAN. It is designed for costumer who need a high speed connectivity, normally to the internet, and have end points spread over a city or a part of city.

8. A heterogeneous network made of WANs & LANs

9. Personal area network A personal area network, or PAN, is a computer network organized around an individual person within a single building. This could be inside a small office or residence. A typical PAN would include one or more computers, telephones, peripheral devices, video game consoles and other personal entertainment devices. If multiple individuals use the same network within a residence, the network is sometimes referred to as a home area network, or HAN. In a very typical setup, a residence will have a single wired Internet connection connected to a modem. This modem then provides both wired and wireless connections for multiple devices. The network is typically managed from a single computer but can be accessed from any device.

10. This type of network provides great flexibility. For example, it allows you to: – Send a document to the printer in the office upstairs while you are sitting on the couch with your laptop. – Upload the photo from your cell phone to your desktop computer. – Watch movies from an online streaming service to your TV.

12. What is the difference between a LAN, a MAN, and a WAN? A LAN (local area network) is a group of computers and network devices connected together, usually within the same building. By definition, the connections must be high speed and relatively inexpensive (e.g., token ring or Ethernet). A LAN connection is a high-speed connection to a LAN. Most connections are either Ethernet (10 Mbps) or Fast Ethernet (100 Mbps), and a few locations can have Gigabit Ethernet (1000 Mbps) connections also.

13. A MAN (metropolitan area network) is a larger network that usually spans several buildings in the same city or town. A WAN (wide area network), in comparison to a MAN, is not restricted to a geographical location, although it might be confined within the bounds of a state or country. A WAN connects several LANs, and may be limited to an enterprise (a corporation or an organization) or accessible to the public. The technology is high speed and relatively expensive. The Internet is an example of a worldwide public WAN.

14. Connection Oriented & Connectionless Services Connection Oriented services – Connection Oriented services, t he source first makes a connection with the destination before sending a packet. – When the connection is established, a sequence of packets from the same source to the same destination can be sent one after another. – There is a relationship between packets. – They are sent on a same path in sequential order. – When all packets of a message have been delivered, the connection is terminated. – Requires a session connection to be established before any data can be sent. This method is often called a "reliable" network service. – the connection oriented services are used in TCP.

15. Connectionless Services – Connectionless Services, the network layer protocol treats each packet independently, with each packet having no relationship to any other packet. – The packet in the message may or may not travel the same path to their destination. – Does not require a session connection between sender and receiver. The sender simply starts sending packets (called datagram) to the destination. – Connectionless communication is just packet switching where no call establishment and release occur. A message is broken into packets, and each packet is transferred separately. – Connectionless service is typically provided by the UDP (User Datagram Protocol). The packets transferred using UDP are also called datagram.

16. Difference between connection oriented and connectionless services 1.In connectionless communication there is no need to establish connection between source (sender) and destination (receiver) but in connection-oriented communication connection must be established before data transfer. 2.Connection-oriented communication is more reliable then connectionless communication. 3.In connection-oriented communication information can be resend if there is an error in receiver side (missing data, corrupt data etc. ) but in connectionless communication it is not possible because the destination does not inform the source about data is received or not.