Networking LAN Technology

7/29/2019 Networking LAN Technology

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Introduction - Networks

LAN (Local Area Network)

Cover limited area (maximum 20km)

Factories, Hospitals, Schools

WAN (Wide Area Networks)

- Cover wider area with high speed digital

lines


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Network

WAN

Network: Classified by place which used

Company A (HQ)

Company A (BR)

Company A (BR)

LAN

LAN


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Local Area Network

LAN: Network located limited place such as inside building or floor.

3F 2F

1F


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Wide Area Network

LAN

LAN

WAN

Common Carrier owned

the Communication line

WAN: Connects between two different places via Common Carriers line


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3.1.1 Features of a LAN

Benefits of LAN

Share resources such as database

Centralized information

Highly reliable, high quality of

communication within limited area

No line charges of use of line Few Transmission Errors

User manage the entire network


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Classification of LAN

Network Topology Star Type

Bus Type

Ring Type

Mid (1 to 2Mbps)

High (100 Mps)

Twisted Pair

Coaxial

Optic-fiber

Infra-red, Radio

Baseband

Broadband

CSMA/CD

Token Passing

CSMA/CA

Transmission Speed

Transmission Media

Transmission Method

Network Topology


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LAN Classification by Connection type and Usage

Backbone LAN

Access LAN

Access LANAccess LAN

Access LAN: Connects personal computers and servers

Backbone LAN: High speed and high reliability which bundles Access LAN


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Network Topology


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3.1.2 Topology of LAN

Terminal 6

Terminal 5

Terminal 4 Terminal 3

Terminal 2

Terminal 1

(1)


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Features of Star Networks

Easy to add and move terminalsconnected

to network Restriction on no. of connectible terminals

and distance from concentrator

One terminal fail would not affect the entire

network If concentrator fails the entire network will

go down



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Features ofbus network are:

Simplest wiring, but ifterminalsis moved

bus wiring must be redone Restriction on length ofbus and no. ofterminals



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Terminal 1

Terminal 2

Terminal 3 Terminal 4

Terminal 5

Terminal 6


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Features ofringnetworksare:

Data passes around the ring in one

direction If destination address matches terminal

then data is seized, otherwise data is

passed on



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3.1.3 LAN Connection Architecture -

continue (1) Peer-to-peer

Requires no dedicated server machine

Each machine considered equal Personal terminals manage all tasks

Simple and cheap to construct

Not suitable for heavy data loads

Not suitable for advanced computations


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Client/Server LAN


continue

CommunicationServer

Client

Host Computer

Client

ClientPrint Server

DB Server


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Client/server LAN

Each computer performs a dedicated role

(eg/printing, database) System resources allocated for specific

roles.

Normal document done on personalcomputers

Used in relatively large scale LAN systems


continue


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3.1.4 LAN Components

The components that make up a LAN

Transmission media

Means that the computers are connected

in the network

Peripheral equipment

Hardware necessary for the construction ofa LAN


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LAN

Cable

Cable

LANConnectionEquipment

ControlEquipment

NetworkInterface

Card


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LAN Transmission media

Twisted pair cables

Coaxial

Optical-fiber cables

Wireless

3.1.4 LAN Components - continue


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Ethernet Cables

X X

X X

X X

X X

Outer Insulation Core Inner InsulationFiber

Fiber-optic

UTP

Insulation (pair) conductor

Coaxial

Insulation Outer ConductorInsulation

Center Conductor


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Twisted pair cable

Max transmission rate: 100 Mbps Transmission Distance: several hundred meters

Noise: resistance: easily affected

Price: Cheap

Cable installation: Easy

Appropriate Scale for Application: Small scale LAN on a

same office floor

Access control method: CSMA/CD token-passing method



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Connection of Cable and Connector

1

2

3

4

123

45678

Connector (RJ-45)

8 Cores, 4 pairs

Cable

UTP

CAT-5

#4,5,7,8: No use (10BASE-T)


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Coaxial cable

Max transmission rate: several hundred Mbps Transmission Distance: up to ten kilometers

Noise: resistance: Relatively resistant

Price: More expensive than twisted cable

Cable installation: More time and effort compared to twisted

cable

Appropriate Scale for Application: Large scale LAN

Access control method: CSMA/CD


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Optical Fiber Cable Max transmission rate: several hundred Mbps

Transmission Distance: up to 100 kilometers

Noise: resistance: Exceptionally resistant

Price: Similar to coaxial cable

Cable installation: Easy, uses trained technicians

Appropriate Scale for Application: High speed LAN systemand ATM-LAN

Light weight, easy to handle

Higher cost on peripheral equipment


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Fiber-Optic Connector


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Wireless

No wiring is necessary

Use infrared ray and radio waves

Easy to move the equipment and the design of

network is more flexible

Susceptible


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3.1.5 LAN Access Control Method

1. Determine Access (TDMA)

Transmission right are allocated to

terminals in advance Terminals can send data in an allocated

order

Terminal take turn on transmission


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Peripheral equipment of LAN

1. Terminator Remove unnecessary data which is not taken by

terminals in BUS LAN

2. Transceiver Connect the drunk cable and the node from the

terminal

Detecting data collision


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Converter

Connects different interface

UTP

HUB

AUI cable

Converter (TPMAU)

100BASE-FXInterface

UTP

Converter

Optic-fiber cable

100BASE-TXInterface


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2. Nondeterministic Access (CSMA/CD,

Token-passing)

Transmission right allocated whilerequest is issued

Transmission rights can be obtained

with good timing

Conflicts would occur

3.1.5 LAN Access Control Method


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3 typical type of LAN System

1. TDMA (Time Division Multiple Access) Control access by dividing the data channel into

specific time division and allocating units (time

slots) of these division to each terminal Allow point-t0-point communication when data is

transmit from terminal X to terminal Y

Data collisions does not occur

Reliable data transmission Time slots wasted if allocated to the terminal

which do not need to do transmission


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2. CSMA/CD (Carrier Sense Multiple Access withCollision Detection)

Used in BUS topology

All the terminals need to be monitor whether data ispassing on the cable

Transmission starts with no data is passed, pauses forstandby when data is passed

Data collide if many terminals transmit data together If collisions is detected, all terminals will have to wait a

specified time before attempt retransmission



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CSMA/CD Method

5 Receive the data

1 Idle Confirmation

NIC NIC

4 Packet Detection 2 Send a packet

Data Data Data

Packet Packet Packet

3 transmissionDestination Info


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Collision


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3. Token passing

Used ring topology LAN

Signal carrying the right to transmit on the cable ispassing around the network

Token carry no data = free token

Token carrying data = busy token

Terminal seizes the free-token and turn it to be busy

token and send with data When other terminal receives the busy token, it get the

data and turn it to be a free token


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Token Passing

A Token is passed around in the network

Free Token: carrying no data

Busy Token: carrying data

-First in First servedmethod

- No Collision


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3.1.6 Inter-LAN Connection Equipment

Connection device between LAN

Interconnection of LAN and LANData exchange is possible

Not connected

Interconnection


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Connection device between LAN

Physical1

Data link2

Network3

Transport4

Session5

Presentation6

Application7

OSI RM

Relay equipment

Repeater

HUB

Bridge

Switching Hub

Router


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1. Repeater

Perform relay functions on the physical layer

Extends the transmission range of the LAN

LAN system connected by a repeater can logically

be regarded as one LAN

Only recognized data as electrical signals (bitstrings)


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Repeater

located in the first layer of the OSI RM, and extend LAN

physically

Data

Data

Relay function Repeater

Hub

-Characteristics-

Physical extension of LAN

Transmission line can be extended


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Repeater Hub (Conventional hub)

Data to B Data to B Data to B Data to B

A B C D

Repeater HUB simply rebroadcast every packet every port.

All terminals cant communicate at the same time.

(share the transmission path)


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3.1.6 Inter-LAN Connection

Equipment - continue

2. Bridge

Perform relay functions on the data link layer

Logical bridges for direct connection of LANsystems

Remote bridges for connection of LAN

system via communication lines (leased lines) Recognized data as one piece of data

(packet)


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Bridge

located in the second layer of the OSI RM

Data is relay by using the MAC address

Data

Bridge

Data forwarding is judged by MAC

address

Unnecessary data is not transmitted to

other segments

Only necessary data is relayed!!


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Bridge Functions


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3. Router

Perform relay functions on the network layer

Interconnect between different networks

Data passes only to the specified party

The router identifies the address (IP address)

of the data and select the route along whichthe data will travel

Reduce traffic load and provide security



Router


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Data is relayed by thenetwork address

Identify the protocolRouter

Router 3

Router 1

Router 2

Network A

Network C

Network B

Router

Third layer of the OSI RM

Network address is used for the path control (routing)

R ti


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Routing

Directly (Port 3)192.168.5.0

192.168.5.2192.168.4.0

192.168.5.2192.168.3.0



Next routerNetwork ID


192.168.5.2192.168.4.0

192.168.5.2192.168.3.0



Next routerNetwork ID

Router 1 Router 2

192.168.1.1 192.168.3.1192.168.2.1 192.168.4.1

192.168.5.2192.168.5.1

192.168.2.1

192.168.1.0 192.168.2.0 192.168.3.0 192.168.4.0

A: direct routing B: indirect routing

Routing table of router 1 Routing table of router 2

A

B


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Bridge vs. Router

BY IP address and port numberBy MAC address protocolPacket filtering

Relay only supported protocolsNoneProtocol

Treats physical network as different

networks

Treats physical network as a networkFunction

RouterBridge


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4. Gateway (network conversion)

To establish interconnection between an OSI

network and a TCP/IP network To obtain interconnection between a network

constructed with vendor-inherent protocols and a

network constructed with the OSI system




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1. Switching Hub

A communication device that employs

switching technology to accomplish high-speed transmission on LAN

Ethernet switch

Token ring switch

Data is switched to the destination terminal asthe MAC address of the data id identifiedinside the switching hub

3.1.7 LAN Speed-up Technology


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Data to B Data to B Data to B Data to B

A B C D

Switching HUB

Port4:

Porty7: DPort3:

Port6:Port2: B

Port5: CPort1: A

Address Table

Switching hubs forward each packet only to the required port referring to

MAC address in the received data.

Possible to communicate between two or more terminals simultaneously.


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3. ATM-LAN (Asynchronous Transfer Mode)

A full-fledged multimedia LAN solution

Enable data transmission at ultra-high speed

3.1.7 LAN Speed-up Technology

Networking LAN Technology

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