LOCAL AREA NETWORK

Presented by :

Tan Teng MengWET010148

Chan Choi Ngor WET020019

Philip Lim Loong HinWET020144

Table of Contents

LAN Definition Presented by Tan Teng Meng

LAN Topology and Device Presented by Chan Choi Ngor

LAN Cabling, ATM and wireless LAN Presented by Philip Lim

Local Area Network (LAN)

What is LAN?

High speed, fault-tolerant data network Cover a relatively small geographic area Connects workstations, personal computers,

printers, and others devices.

LAN Technologies

EthernetToken RingFDDI

Ethernet

Most widely-installed Specified in a standard, IEEE802.3 Connected to the cable and compete for access using a

CSMA/CD protocol shared media - media access is controlled on a “first come,

first serve” basis 10BASE-T provides transmission speeds up to 10 Mbps 100BASE-T provides transmission speeds up to 100 Mbps

Token Ring

Second most widely-used Specified as IEEE 802.5 Connected in a ring or star topology Provides for data transfer rates of either 4 or 16

Mbps

FDDI

A set of ANSI and ISO standards for data transmission Can extend in range up to 200 km Based on the Token Ring protocol Used on the backbone for a WAN

Advantages and Disadvantages with LANs

Advantages Disadvantages

Recourse Sharing Vulnerability

Communication Poor password

Central and routine back-ups costs

Users can login from wherever Installation

security Maintenance

Less Expensive Systems Training

Performance

Types of LANs

Server-based LAN Has a dedicated machine/computer, that has the file

server software located on it. All the workstations point towards this computer for

accessing the resources

Peer-to-Peer LAN Small & has the files server software installed on each

of the workstations Acting as both a file server & a workstation.

LAN Transmission Methods

1. Unicast - a single packet is sent from the source to a destination on a network.

2. Multicast - consists of a single data packet that is copied and sent to a specific subset of nodes on the network

3. Broadcast - consists of a single data packet that is copied and sent to all nodes on the network

LAN Topologies

Physical topologies Bus topology Ring topology Star topology Extended star topology Hierarchical topology Mesh topology

Logical topologies Broadcast topology Token passing

Bus Topology

uses a single backbone segment (length of cable)

the hosts connect to it directly.

Ring Topology

connects one host to the next and the last host to the first

Star Topology

connects all cables to a central point ( Hub or Switch )

Extended Star topology

links individual stars together by linking the hubs or switches

extend the length and size of the network

Hierarchical topology

similar to an extended star linking the hubs/switches together, the system is

linked to a computer The computer controls the traffic on the topology

Mesh topology

is used when there can be absolutely no break in communications.

Broadcast topology

Each host sends its data to all other hosts on the network medium

First come, first serve Is the way that Ethernet works

Token Passing

Controls network access by passing an electronic token sequentially to each host

The host receives the token can send data on the network

If the host has no data to send, it passes the token to the next host & the process repeats itself

Devices in LAN

A LAN consists of PC and external hardware, named hosts.

Apart from hosts, there are other devices functioning as the connecting medium : Repeater Hub Bridge Switch Router

Network Interface Card

Printed circuit board, also called network adapter. Carries a MAC address ( Layer 2 device ) Each hardware and PC in the network must have a NIC

to be connected to a network.

Repeater

Used to lengthen the range in the network. Layer 1 device which receive and transmit the

data. Will not check for error, or determine the

destination.

Hub

Layer 1 device also called multi-port repeater Receive and transmit data without checking for

error or consistency of data packet. Advantage – decrease wiring and increase

reliability.

Bridge

Operates via MAC address ( Layer 2 device ) Connect different part of the LAN while filtering

the traffic to keep local traffic local, yet allow connectivity to other parts.

Keeps track on MAC address on each side

Switch

Layer 2 device also called multi – port bridge. Filters data by switching data only to the port

where the appropriate destination is located Can be used to segment networks.

Router

Layer 3 device used to regulate traffic Forward the data packet to appropriate host via

IP address. It also examine data packets and choose the

best path for it. Can connect different Layer 2 technologies.

Wire / Cable

Another essential component of a network, example LAN

There are different wire / cable types to be chose based on the range and bandwidth the network requires.

Example of cable : UTP STP Fiber Optic Coaxial Cable

Unshielded Twisted Pair

Consists of 2 – 4 unshielded copper solid or stranded wires. Most network protocol using the UTP will require 2 pairs of wires,

one for transmission and one for reception. General choice of wiring in office and home, with the RJ45

connectors Comes in 5 categories based on the EIA/TIA standards

Unshielded Twisted Pair ( cont )

Advantage – Inexpensive and easy to work with. Flexible and can fit in full conduits. Many people familiar with UTP.

Disadvantage – Prone to interference. Short range of distance.

Speed and throughput – 10 – 100 MbpsMedia and connector size – smallMaximum range of connection – 100m

Shielded Twisted Pair

Similar to the UTP in operation and design. Reduction of noise and interference, from both within and

outside. More expensive and difficult to install compared to UTP

Fiber Optic

Cable with glass and plastic mediumUses light ( laser ) to transmit data.Multimode fiber is often used in LAN.Has a low error rate and degrading is

lower. High performance and longer range.

Expensive and difficult to implement.Normally used as backbone in a LAN.

Fiber Optic Cable

Coaxial Cable

Consists of a central copper core encased in a plastic sheath

Quite easy to implement, and popular choice in LAN Speed and throughput – 10 – 100 Mbps Media and connector size – medium Maximum cable length – 50m

Coaxial Cable

Divided into 2 types : Baseband

One channel – single message a time at a high speed

Able to handle 10 – 80 Mbps An important component in Ethernet Easy to plug in / out a network without disturbing

network flow 500m optimum range Unable to send integrated signals

Coaxial Cable

Broadband Can carry several different signals broadcasted at

different frequency simultaneously Possible to allocate 6-346 MHz for forward and 25

MHz for reception channels Can be single cable or dual – cable. Can have 50 channels broadcast at 5 Mbps

maximum Require more planning, and installation of amplifiers

are needed

Asynchronous Transfer Mode

Another popular networking technology working in a different way compared to LAN

It is possible to implement ATN in a LAN, and vice – versa, by emulating the 2 technologies.

Differences between LAN and ATM

Connection : LAN is connectionless, ATM is connection – oriented.

Size of transmission : LAN have variable packet size, up to 1.5 kilobytes,

while in ATM, each cell is 53 bytes. Broadcast :

LAN support broadcast and MAC address, while ATM is switch-based

Mode : LAN work in best – effort mode, ATM is similar except

how it provide effective congestion control

Wireless LAN

A traditional LAN uses electricity and light as medium of data transmission.

Wireless technology uses the atmosphere as transmission medium

While it is applicable, wireless LAN is costly, and have high error rate