Secretariat LAN PPT
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Secretariat LAN Presentation Transcript:
1. SEMINAR ON EXPANSION OF NETWORKS WITH SPECIAL REFERENCE TO SecLAN2. INTRODUCTION:
A computer network is a group of computer and devices interconnected by computer channels. It allows sharing of resources and information among interconnected devices. Most networks use distributed processing in which a task is divided among multiple computers. In distributed processing, instead of one single large machine being responsible for all aspects of a process, separate computers handle a subset. A network must be able to meet a certain number of criteria. The most importatnt of these are performance, reliability and security.
3. What is LAN:
LAN or Local Area Network is a computer network covering a small physical area such as a home, an office or a small group of buildings. A LAN usually has high data transfer rates, small geographic place, and it does not requires leased telecommunication services. Other characteristics of LAN include full time connectivity to load services, generally lower in cost than a WAN and cabling in primary transmission medium.
4. LAN Design:
The design of a network affects most when it comes to the performance of the network. There are basically two design processes: General network design process Good network design rule
5. General network design process:
It consists of following three general elements: Enviornment given: it includes location of hosts, servers, terminals and other end nodes. Performance constraints: it consists of network reliability, traffic throughput and host/client computer speeds. Internetworking variables: it includes the network topoligy, line capacities and packet flow assignments.
6. Good network design:
It is also known as the 80-20 rule. In a properly designed network, 80 percent of the traffic on a given network segment is local. Not more than 20 percent of the network traffic should need to move across a backbone. Backbone congestion can indicate that traffic patterns are not meeting the 80-20 rule. In this case, network performance can be improved by: Moving resources Moving users Adding servers.
7. Virtual local area network
VLANs or Virtual LAN are used to simulate several logical Ethernet networks on the same physical infrastructure. VLANs are independent broadcast domain which don’t share any layer two communications. There are two main ways of defining VLANs: Per service: common services are grouped in a common VLAN, across many locations. Per location: VLAN scope is limited to a location, for example to a floor or a computer center.
8. OSI MODEL:
The open system interconnection model is a layered frame work for the design of network system that allow for communication across all types of computer systems. It consists of seven separate but related layers: Physical layer Data link layer Network layer Transport layer Session layer Presentation layer Application layer
9. Transmission media in local area network
The Transmission medium is material substance (solid, liquid or gas) which can propagate energy waves. There are three types of transmission medium used in LAN’s. These are twisted pair, coaxial cable and optic fiber. Twisted pair is mostly used in connections of star and hub networks. Coaxial cable is one of the most important kinds of transmission medium used in LAN’s. It is mainly used in bus network with baseband and broadband transmission. An optic cable is often used in backbone networks because its wide bandwidth is cost effective.
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