Computer Networks Part 1 LAN, WAN Adv DisAdv Net Topology

Network Collection of computers and other devices that can communicate with each other and exchange messages. Networked computers can share: Hardware Software data

Advantages of a network? Reduce resource requirements Files and files storage, printers, databases, media writers, etc. Reduce cost Increase efficiency and effectiveness Improve Communication email File sharing via server Internet, Intranet and extranet Sharing devices such as printers saves money. Software licences are likely to be cheaper than buying several standalone licences. Files can easily be shared between users. Network users can communicate by email and instant messenger. Security is good - users cannot see other users' files unlike on stand-alone machines. Data is easy to backup as all the data is stored on the file server.

Network Disadvantages Purchasing network cabling and file servers which can be expensive Managing a large network requires a trained network manager If the file server breaks down, the files on the file server become inaccessible Viruses can spread to other computers throughout a computer network. Email might still work if it is on a separate server. The computers can still be used but are isolated.

Network Terms Workstation: a computer connected to a network Server: computer that provides services to users such as access shared files, file storage, etc. Node: any device connected to a network

Types of Networks Local Area Network (LAN) Wide Area Networks (WAN) WLAN

LANs: Local Area Networks LAN covers a small area such as one site or building LAN is often a private network that belongs to an organization or business (e.g. School or a college) LAN uses cables or low-power radio for the connections

LANs: Local Area Networks

WANs : Wide Area Networks WAN covers a large geographical area and large distances (states, countries, continents) WANs are made of several LANs connected with each other Internet is a WAN E.g. an organization/business that has offices in different countries uses WANs to link the office LANs together

WANs : Wide Area Networks

Types of Networks Peer-to-Peer Network Client/Server Network

Peer-to-Peer Network Allows users to access resources on other computers and share resources on their computer All computers in Peer-to-Peer are considered equal (Same) Each computer makes some of its resources directly available to other network computers without the need for a coordinator (server) Advantages Simple to setup- no technical support needed Inexpensive Disadvantages Inflexible Not secure Limited scope (scalability

Peer-to-Peer Network

Client/Server Network Many client computers connected to a single central server computer A server is a host that runs server programs to share resources with clients A client does not share any of its resources Clients communicates with servers to request services and resources

Client/Server Network