Elementary Statistics and Computer Application

Local area networks

• Local Area Networks are generally called LANs, are privately owned networks within a single building or campus a few kilometers in size.
• They are widely used to connect personal computers and workstations in company offices and factories to share resources and exchange information.
LANs distinguished from other kinds of networks by three characteristics:

1. Their size
2. Transmission technology
3. Their topology
• LANs are restricted in size.
• They use a transmission technology consisting of a single cable to which all the machines are attached.
• Traditional LANs run at speeds of 10 to 100 mbps have low delay and make very few errors.
• Newer LANs, may operate at higher speeds, up to hundreds of megabits/sec(1,000,000 bits)
• Broadcast networks can be further divided into static and dynamic, depending on how the channel is allocated.
• Static allocation would divide time into discrete intervals and run a round robin algorithm, allowing each machine to broadcast only when its time slot comes up.
• They waste the channel capacity when a machine has nothing to say during its allocated slot, so dynamic method is preferred.
• Dynamic allocation methods for a common channel are either centralized or decentralized.