What is Local Area Network(LANs)

Local Area Network(LANs)-

                Local area Networks (LANs) are the most common networks.  A LAN has the following characteristics:

·         The network operates in a contained area.  This could be a single floor in a building or simply within a single building.

·         The host within the LAN is interconnected with high-bandwidth network connections such as Ethernet or token ring, or use newer technology such as wireless networks.

·         All facets of the LAN often are privately managed. No third parties are required for connectivity solutions.

·         LAN services are available on a 7-dayh, 24-hour basis.

Type of Network -

·         Peer-to-peer networks

·         Server-based networks

Peer-to-Peer networks-

                              Peer-to-Peer networks operate with no dedicated servers on the network.  Each host functions as both a client and a server.  The user at each host determines what information or peripherals he is willing to share with the other members of the network.  Peer-to-Peer networks generally are relegated to smaller organizations; they do not scale well to larger ones.  They have several security issues as a result of each host’s capability to control its own security, which decentralizes security control.

Server Based Network-

                In server-based networks, at least one host is dedicated to server functionality. Client computers do not share any information with other computers.  All data is stored on the central server.  Most corporate networks are based on this methodology. Within a server-based network, servers can play several roles. These roles include the following:

·         Directory Servers:These provide a central directory service for management of users,  groups, and host objects to allow for centralized authentication and authorization using the central directory.

·         File and Print Servers:  These provide a secure repository for all data.  They also can manage printqueues that provide access to network-sharable print resources.

·         Application Servers:  These provide the server side of client/server applications. In a client/server environment, the client runs a small version of the program that allows connectivity to the server.  The server side of the application is used to perform processor-intensive queries on behalf of the client.  Example of application servers includes Web servers and database servers.

·         Mail Servers:  These provide electronic-message capabilities for the clients of the network.  With the use of gateways, mail transport can take place between heterogeneous mail systems.

·         Security Servers:  These provide security to the local area network if it is connected to any larger networks such as the Internet.  Security servers include firewalls and proxy servers.

·         Remote Access Servers:     These enable external data flow to occur between the network and remote clients.  A remote client can use a modem to dial in to the local area network, or alternatively use a technology known as tunneling or Virtual Private Networks (VPNs) to connect to the remote network over a public network such as the Internet.  The system that allows the remote client to connect to the corporate network is the remote access server.  A remote access to the network, or one or more virtual ports to allow tunnel connections. After the client has connected to the remote network, the user can function as if he or she were directly connected to network using a network card.