Network Characteristics

Networks are broadly classified into two types: local area networks (LANs) and wide area networks (WANs). The WANs are also referred to as long-haul networks. The key characteristics that are often used to differentiate between these two types of networks are as follows:
1. Geographic Distribution:
The main difference between the two types of networks is the way in which they are geographically distributed. A LAN is restricted to a limited geographic coverage of a few kilometers, but a WAN spans greater distances and may extend over several thousand kilometers. Therefore LANs typically provide communication facilities within a building or a campus, whereas WANs may nationwide or even worldwide.

2. Data rate:
Data transmission rates are usually much higher in LANs than in WANP- transmission rates in LANs usually range from 0.2 megabit per second to 1 gigabit per second. On the other hand, transmission rates in WANs usually range from 1200 bits per second to slightly over 1 Mbps.

3. Error rate:
Local area networks generally experience fewer data transmission errors than WANs do. Typically bit error rates are in the range of 10 to the power of -8 to 10 to the power of -10 with LANs as opposed to 10 to the power of -5 to 10 to the power of -7 with WANP-

4. Communication link:
The most common communication links used in LANs are twisted pair, coaxial cable and fiber optics. On the other hand since the sites in a WAN are physically distributed over a large geographic area, the communication links used are by default relatively slow and unreliable. The communication links used in WANs are telephone lines, microwave links and satellite channels.

5. Ownership:
A LAN is owned by a single organization because of its limited geographic coverage. A WAN is usuall formed by interconnecting multiple LANs each of which may belong to a different organization. Therefore administrative and maintenance complexities and costs of LANs are usually much lower than for WANs.

6. Communication cost:
The overall communication costs of a LAN is usually much lower than that of a WAN. The main reasons for this are lower error rates, simple routing algorithms and lower administrative and maintenance costs. The cost to transmit data in a LAN is negligible since the transmission medium is usually owned by the user organization. However with a WAN, this cost may be very high because the transmission media used are leased lines or public communication systems, such as telephone lines, microwave links and satellite channels.