Local Area Networks (LAN) are small networks, with a short distance for the cables to run, typically a room, a floor, or a building. - LANs are limited by number of computers and distance covered. - Usually one kind of technology is used throughout the LAN. The most common is Ethernet. Examples: Network inside the school Network inside a business Network inside your home

Peer-to-Peer Networks A Peer-to-peer network is often called a workgroup. There is no single controlling computer. Each computer acts like a server, providing some service, while also acting like a client, receiving services from the other computers. There is no hierarchy among the computers. They are all equal. There tends to be no administrator responsible for the network. It is ruled by consensus. Most home networks, and LAN parties are set up in this fashion.

Advantages of peer-to-peer networks: Low cost Simple to configure User has full accessibility of the computer Disadvantages of peer-to-peer networks: May have duplication in resources Difficult to uphold security policy Difficult to handle uneven loading

Where peer-to-peer network is appropriate: 10 or fewer users No specialized services are required Security is not an issue Only limited growth is foreseeable for the future

Clients and Servers Clients Workstation Network Clients (Workstation): Computers that request network resources or services. Some clients are totally dependent on the server. Most often, the client is a stand alone computer, with its on processor, RAM, hard drive and peripherals, but is connected to boot through the network system via an authentication password process. Once logged into the network, this computer is capable of accessing data or services held on the network servers, based on either the machine’s access or the user’s access level.

Clients and Servers Servers: Network Servers: Computers that manage and provide network resources and services to clients. Usually have more processing power, memory and hard disk space than clients. No user will sit directly at a Server and use it as a terminal. Servers run a Network Operating System that can manage not only data, but also users, groups, security, and applications on the network. Some networks utilize several servers to perform different tasks, as well as redundancy equipment.

Advantages of client/server networks: Client Server networks facilitate resource sharing as well as centrally administrate and control access to programs and data. This type of network additionally facilitates system backup and improves fault tolerance. Security is enhanced since only administrators or limited support personnel have access to server. Client Server networks also can support more users than with peer-to-peer networks.

Disadvantages of client/server networks High cost for Servers. Because of the nature of the hierarchy of this type of network, you will need to configure the network with a little more thought and care than with a peer to peer network. You also introduce a single point of failure to the system.

Server networks may include special purpose types of servers, utilizing special software to provide specific services to the users. These include: SANs Storage Area Network Servers Application Servers Communication Servers Domain Controllers Directory Servers Domain Name Servers Mail Servers Web Servers Fax, File, and Printer Servers

SANs Servers Storage Area Networks offer many advantages, including fast access to SAN storage areas; backups from a single location; fastest, more reliable storage subsystems, including hot- swappable power supplies and disk drives; extra levels of security and access control; as well as providing an easier way to increase storage capacity for the entire network.

Application Servers Application servers supply the server side of the client/server applications. Network versions of software are installed here, and workstations connect to this server to run the program, instead of having many copies installed on each workstation. This can save money and installation time / problems for networks. They also provide processing service and handle requests for file or print services.

Communication Servers Allow users outside the network to access network’s resources (inbound communications). Sometimes permit users on the network to access resources outside their local network (outbound communications).

Domain Control/Directory Servers Domain Control and Directory servers let users locate, store, and secure information about their network and its resources. These servers generally combine computers, users, groups, and resources into logical domains, hence the name. This is the primary server for logging into most networks.

Fax Servers For companies with an inordinate amount of fax messaging, a fax server manages fax traffic on the network. It receives incoming faxes via telephone, and then distributes faxes to recipients. It also collects outgoing faxes from the workstations to send via telephone to distant destinations.

File and Print Servers Far more common are File and Print Servers. These provide basic network file storage and retrieval, while providing access to networked printers. Users run applications locally but keep data files on file server and print hard-copies to networked printers, coordinated through the print server.

Mail Servers Mail servers handle messages, both incoming and outgoing. They provide “store and forward” services by hold incoming messages until users can access them. They can also hold outgoing messages until forwarded to their destinations via the Internet. The most widely recognized mail server is probably Microsoft Exchange Server, with MS Outlook used as the mail client, although there are many other options.

Web Servers Web servers have gained popularity faster than any other service. Many companies use WWW and TCP/IP protocols internally to distribute information via an Intranet. Others set up Web servers to handle Internet traffic as well.

WANs, or Wide Area Networks are those networks which cover large geographic areas. They typically have service providers, usually the local telcoms, to connect their various LANs together. An example would be a large, multinational corporation with offices all around the world.