LOCAL AREA NETWORK

1) Local Area Network (LAN)




• The IEEE 802 LAN is a popularly used shared medium peer-to-peer communications network that broadcasts information for all stations to receive.
• The LAN enables stations to communicate directly using a common physical medium on a point-to-point basis without any intermediate switching node being required.
• A LAN is a system composed hardware and transmission media and software.
• LANs are privately owned networks within a single building or campus of upto few km in range.



• It generally use only one type of transmission media.
• LAN can provides users
1) Flexibility
2) Speed
3) Reliability
4) Adaptability
5) Security
6) Transparent interface
7) Access to the other LAN and WAN
8) Hardware and software sharing
9) Centralized management
10) Private ownership of the LAN.
• Attributes of LAN
1) The LAN transmits data amongst users stations
2) The LAN transmission capacity is more than 1 Mbps.
3) The LAN channel is typically privately owned by the organization using the facility.
4) The geographical coverage of LANs is limited to areas than 5 square kilometres.

• LANs are typically identified by the following properties –

1. Multiple systems attached to shared medium.
2. High total bandwidth (~10 Mbps).
3. Low delay.
4. Low error rate.
5. Broadcast / Multicast capability.
6. Limited geography (1-2 km).
7. Limited number of stations.
8. Peer relations between stations.
9. Confined to private property.
• The low level forms of LAN are those described by the IEEE standard 802. This standard described operation upto and including OSI layer 2. Individuals may build what they like on top these basic protocols.
• A common step to higher level protocols is called TCP/IP which provides OSI layer 3 and 4 functionally, on top of this may be found a set of protocols commonly called telnet protocols.
• At the lowest level the IEEE 802 specifies spilt into 3 corresponding to three but common LAN structures these are-
802.3, 802.4, 80205, standardsb for topology.
• The following characteristics are differences one LAN from another:

1. Topology: The geometric arrangement of devices on the network. For example, devices can be arranged in a ring or in a straight line.

2. Protocols: The rules encoding specifications for sending data. The protocols also determine whether the network uses a peer-to-peer or client /server architecture.

3. Media: Devices can be connected by twisted-pair wire, co-axial cables, or fiber optic cables. Some networks do without connecting media altogether, communicating instead via radio waves.