LOCAL AREA NETWORK

Architecture system

Presented By: Ayushi Gagneja

HOW CAN I CONNECT TWO PC’S ?

LAN - LOCAL AREA NETWORKS

Many applications of fiber-optic communication require networks with a large number of users within a local area such that any user can access the network randomly to transmit data to any other user. Group of computers and associated devices that share common communications line.LAN systems are used by colleges, universities, office buildings, and industrial plants, for making use of optical fiber.Due to small transmission distances (<10 km), fiber losses are less.Main advantage of using optical fibers is the large bandwidth offered by OFC systems.

FIBER CABLE V/S COPPER CABLE

COMPARISON OF FIBER CABLE AND COPPER CABLE IN LAN ARCHITECTURE

COPPER CABLECopper-based systems average >2 outages per year due to electromagnetic interference, RF interference, crosstalk etc.Difficult to install and test, while occupying large space.Crosstalk occurs.Error rates = few per minuteComparably smaller distances

FIBER OPTIC CABLEOptical fiber`s immunity to these parameters increases network reliability by at least 60%Not difficult to install and test. Two-fiber cable is 25-40% lighter and occupies 15% less space.No problem of crosstalk, Has infinite bandwidth and very reliable.Error rates = few per monthIncreased transmission distances increases network design flexibility.

LAN TOPOLOGIESBusRingStar

BUS TOPOLOGYEthernet, is the best example of a network protocol used to connect multiple computers and used by the Internet.It operates at speeds up to 1 Gb/s by using a protocol based on carrier-sense multiple access (CSMA) with collision detection.Successful when coaxial cables are used for the bus , but difficulties arise when optical fibers are used. Limitation: Losses occurring at each tap, which limits the number of users.

RING TOPOLOGYConsecutive nodes are joined by point-to-point links in closed loopData transmitted in framesMedium access control is needed to determine when station can insert frame using a token.The use of ring topology for fiber-optic LANs has been commercialized with the standardized interface known as the fiber distributed data interface(FDDI). It operates at100Mbps by using multimode fibers and 1.3µm transmitters based on light-emitting diodes(LEDs). It is designed to provide backbone services such as the interconnection of lower-speed LANs or mainframe computers.

FDDI(FIBER DISTRIBUTED DATA INTERFACE) Standard for data transmission on fiber optic lines in a LAN that can extend in range up to 200 km (124 miles). Provide backbone services like the interconnection of lower-speed LANs or mainframe computersThe FDDI protocol can support thousands of users. An FDDI network contains two token rings, one for possible backup in case the primary ring fails. The primary ring offers up to 100 Mbps capacity. If the secondary ring is not needed for backup, it can also carry data, extending capacity to 200 Mbps.

STAR TOPOLOGY

Each station connected directly to central nodeCentral node can broadcast (hub)Central node can act as frame switch retransmits only to destination today’s technology

Classified as Active and Passive star networks:In active-star configuration, incoming optical signals are converted to the electrical domain through optical receivers.

In passive star configuration, distribution takes place in the optical domain through devices such as directional couplers.

For an ideal N×N star coupler, the power reaching each node is simply PT/N (neglecting transmission losses) since the transmitted power PT is divided equally among N users. For a passive star composed of directional couplers, the power is further reduced because of insertion losses and can be written as

PN =(PT/N)(1− δ )^log2N, where δ is the insertion loss of each directional coupler. If we use δ = 0.05, PT = 1 mW, and PN = 0.1 µW as illustrative values, N can be as large as 500 as compared to the case of bus topology where N is 50.A relatively large value of N makes star topology attractive for LAN applications.

STAR TOPOLOGY CONT..

ADVANTAGES OF OPTIC CABLES IN LAN

Companies use fiber optic cables to set up their LAN don’t worry aboutdangling & tangled cables data transmitted at higher quality and speed than with other network applications

with no fire hazard because no electricity runs through the cablesare rugged as they are immune to electromagnetic interference (EMI), extreme temperatures, and even lightning strikes

easier and faster to installnearly limitless bandwidth capacity and ease of upgrade

Bandwidth demand will only grow, not shrink, in your local area network. Your LAN must support not only today's demands for voice, video and data, but future requirements like security and building automation !!