Thursday 22 November 2012

LAN vs. WAN

A local area network (LAN) exists in a house or a university campus, while a wide area network (WAN) exists over many office buildings separated by a vast distance. The office buildings in a WAN may be in different countries or even continents. For example, the headquarters building may be in the USA, the regional office building may be in the UK, and the branch office building may be in India. The workers in the three buildings use WAN to collaborate with each other. The Internet can also be considered as a WAN.

Difference between LAN and WAN

The other difference between LAN and WAN, is the speed of the network. The maximum speed of a LAN can be 1000 megabits per second, while the speed of a WAN can go up to 150 megabits per second. This means the speed of a WAN, is one-tenth of the speed of a LAN. A WAN is usually slower because it has lower bandwidth. 

Computers in a LAN can share a printer, if they are all in the same LAN. On the other hand, a WAN cannot share a printer, so a computer in one country cannot use a printer in another country. A LAN does not need a dedicated computer to direct traffic to and from the Internet, unlike a WAN that needs a special-purpose computer, whose only purpose is to send and receive data from the Internet. 

Another comparison between LAN and WAN is the cost of the network. A WAN is more expensive than a LAN. It is easier to expand a LAN than a WAN. The equipment needed for a LAN is a network interface card (NIC), a switch and a hub. On the other hand, the equipment needed to connect a WAN to the Internet is a modem and a router. The modem may be a cable modem or a DSL modem that is connected to a wall jack, while the router should be configured so that it can handle the packets traveling between the WAN and the Internet. 

There is a difference in the networking standard used. A LAN uses the Ethernet standard, while a WAN uses the T1 standard. Before Ethernet, the protocols used for LAN were Attached Resource Computer Network (ARCNET) and Token Ring. The protocols used for WAN are Frame Relay and Asynchronous Transfer Mode (ATM). Another protocol for WAN is Packet over SONET/SDH (PoS), where SONET stands for Synchronous Optical Networking and SDH stands for Synchronous Digital Hierarchy. The first WAN protocol was X.25, while an advanced WAN protocol is Multiprotocol Label Switching (MPLS). The hardware in a LAN is connected with 10Base-T cable connectors, while a WAN is connected via leased lines or satellites. 

Here is an explanation of LANs and WANs. A LAN is easy to set up, as you need to slip the NIC into the PCI slot (for desktop computers) or PCMCIA slot (for laptop computers). You also need to install the driver for the NIC. The NIC can be connected to the network using the RJ45 port. 

On the other hand, a WAN is very difficult to set up. There is often an appliance to optimize the WAN. There is also a device to cache WAN data, so workers in the branch office can quickly access documents. The router also has Quality of Service (QoS) built in, so that it gives priority to certain kinds of traffic. 

There are various topologies available in LAN and WAN networking. The most common topologies in LAN and WAN networks are ring and star. The ring topology is a network in which every node (every computer) is connected to exactly two other nodes. The star topology is a network in which all the nodes (called leaf nodes or peripheral nodes) are connected to a central node.
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