Introduction to Local Area Networks

Introduction to Local Area Networks

1/32copyright © 2015 by schlager communications services GmbH

Introduction toLocal Area Networks

ronaldschlager.com © Ronald Schlager



Overview

Why Local Area Networks?

Characteristics of LANs

Typical Fields of Application

Communications Characteristics

Environmental Characteristics

Features

Network Topologies




Local Area Networks are use for information interchange between devices of network users

Network




Office automation (paperless (?) office)

Common use of mass storage (e.g. harddisks) or printers Direct information exchange between users

Internet access

Telephony integration into networks (Voice over IP)

Video conferencing and video surveillance

Mobilizing of devices and applications

„Virtualization “ of systems (services, elements)

„Cloud Computing“ (services out of the network, out of the „Cloud“)



Characteristics of LANs - Today

Limited size

Most often private ownership

Often owner managed

No stringent use of certain protocols

Flexible physical and logical structure

High bitrates

Limited use of multimedia applications Practical tip:

1000 Mbps (1 Gbps) in the workgroup is

state of the art

Practical tip: 1000 Mbps (1 Gbps) in the workgroup is

state of the art



Characteristics of LANs - Tomorrow

Shift of LAN technology into WANs (fluent transition) Users are not the owners of LANs - Outsourcing Outsourcing partners offer external management TCP/IP is common protocol architecture

Fully redundant and reliable physical network structure

Logical structure on demand(depends on intelligence of active network elements)

Bitrate of 1 - 10 Gbps to the desktop computer, 10-100 Gbps the server, 100 Gbps in backbone

Full multimedia support



Typical Fields of Application

Office communication

Factory automation

Laboratory automation

Building automation

Security technology (e.g. video surveillance)

Mobility (cars, airplanes, ships,...)



Communications Characteristics

Office LANIndustria LAN

Validity periodof dataYears

Fractions ofseconds

Amounts of dataGiga Bytes -Tera Bytes

BitsBytes

DelaySeconds -Minutes

Fractions ofseconds

Number of networked stationsMany Few



Environmental Characteristics

Office LAN Industria LAN

Ambient temperature0 - 40oC 0 - 60oC

Electromagnetic interferencelow high

Vibrationsweak

(exception: earthquake)strong

Pollutionlow high



Features – Building Blocks of Computers - Example

Personal Computer Hardware

Operating system(e.g.

Microsoft Windows,Linux)

Applicationprogram(s)

(e.g. text processing)









System hardware

Motherboard, CPU, memory, power supply,

case, cooling devices

Mass storage

Harddisk, diskettes, CD-ROM, DVD, removable disk drive

System software

System management(hardware, software)

Link betweenapplication software

and hardware

Application software

Word processing, spreadsheet,

database, book keeping,

payroll, warehouse management

email, Web,...







Communications system

(e.g. TCP/IP)



Networkinterface

cardCommunications

hardware

Physical interfaces,signal generation,

signal tranmission, reception

Communications software

Interface control,logical communication



Features – Internal Networking

Server

Hub

Client

Client

Client

Printer

Printer

Centralized management of data (files)

andprint jobs,

centralized data processing

Data input and outputLocal data processing,

Local data storageAdditional service:

Performs local print jobs

Signal distribution,switching of information

betweenstations



Features – Inter-Site Networking

Example

Router Router

Wide Area Network(WAN)

RoutingLine backup

Least cost routingInterface adoption

Security

Transfers information across large distances

Example: Internet

LAN

ClientClient

Client

Server in head office

LAN

ClientClient

Server inbranch office


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Example

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LAN

Features – Internet Access

Router

Internet

Firewall

Web Server

Demilitarized Zone (DMZ)

Client

InternetServer

Internet User

ClientClient

CorporateServer

RoutingSecurity

(prevention of attacks, viruses, banned content,...)



Features - Integration of external Users

Example

Router

Internet

Firewall

Security Server

WLAN

Mobile phoneof mobile user

Mobile radio

LAN

ClientClient

Client

CorporateServer

Desktop computer ofhome user

Notebook of mobile user

Controls access rightsand allows or blocks

access to corporate services



Features – Voice Integration in LAN (Voice over IP)

MultimediaGateway

TelephonyServer

Conferencingunit

VoIP device(Softphone)

Supports voice communication, optional video and data communication

Take care of delays and bandwidth!

Take care of delays and bandwidth!

VoIP device(Hardphone)

Public Switched Telephone Network

ISDN phone

LAN

Session controlControl of terminalsControl of gateways

AccountingBandwidth management

Conference(min. 3 partners)

Connection establishment

and release

Signal mix

Optional:Interconnects LAN and

PSTN Signalling



Features – Video Surveillance over LANs (Video over IP)

Video Server

Monitor

Monitor forvideo

presentation

Videostorage

and processing

Video transmission



Features - Mobilization

Client Mobilization:

User Mobilization:

AppApp App App



Features - Virtualization

Virtualization in IT

Fields of application (examples):

System technology (CPU, RAM, harddisk, operating system, applications,...)

Servers, desktops, mobile devices

Network elements (switches, router)

Network connections

Data centers

Advantages: flexibilityCost reduction

Advantages: flexibilityCost reduction


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Features - Cloud Services

Public or private cloud services:

Computer and/or storage capacity “migrates” into the cloud

Advantages:

Use of software out of the cloud

Affordable storage and distribution of data

Co-operative work with data

Disadvantage:

Depending on solution no information about storage location

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Network Topologies - Star

Simple Star/tree:

Problem: reliabilityProblem: reliability

UniversalFlexible

FastEasy to implement

Future-proof




SwitchSwitch SwitchSwitch

Point-to-Point


Line


SwitchSwitch SwitchSwitch SwitchSwitch



Star




Tree







SwitchSwitch

SwitchSwitch

SwitchSwitch

SwitchSwitch

SwitchSwitch

SwitchSwitch

SwitchSwitch

SwitchSwitch

Mesh

Ring



Network Topologies – Example: Star/Mesh Network

Problem: routing

Problem: routing

Ethernet

Redundancy increasesreliability



Network Topologies - Bus

Simple bus

Bus/tree:“Segment”

(= coaxial cable with termination resistors at both ends)

Easy to implementTotal failure in case of broken media

Hard to troubleshootSupports only 10 Mbps in LAN!

Problem: Not future-proof in

office LANs !

Problem: Not future-proof in

office LANs !„Ethernet“



Network Topologies - Bus - Example

Universal Serial Bus (USB)

To interconnect computers („hosts“) with peripheral devices

Hierarchical, serial bus system

USB hub

USB hub

USB hub



Network Topologies - Bus – Example: Field Bus System

Supports communication beteen simple field devices in industrial area and control systems

Replace single-wire harnessing

Valves, sensors, controller, flow rate measuring device, frequency inverter, barcode reader, fire detector,...

Programmablelogic control

Roboter control

Automationdevice ....



Network Topologies - Ring

Single ring (without redundancy)

Multiple rings (with redundancy)

Complex network designMost often redundant rings

Token Ring4, 16 Mbps

100, 1.000 Mbps

Problem: No market

acceptance of ring topology in office

LANs!

Problem: No market

acceptance of ring topology in office

LANs!



Network Topologies – Ring - Example

Interconnected „Ethernet“ switches forming a loop:

Redundancy!

„Ethernet“ 1, 10 Gbps

40, 100 Gbps

Attention: requires intelligent switches!Attention: requires

intelligent switches!



Network Topologies – Typical Characteristics

Star Bus Ring

Basic Topology

Complexity

Expandable

Redundancy

Characteristics

Scaleable

Future-proof

Transmissionprocedure

Simple

Yes

No

Yes

Yes

Serial protocol,CSMA

Simple

Yes

No

Yes

Office: NoFactory: Yes

CSMA, Token

Complex

Yes

Yes

Yes

Office: YesFactory: Yes

Serial protocol,CSMA, Token



Resources

Visit Ronald Schlager´s resources for more information:

Courseware: „Fundamentals of Local Area Networks - Part 1 / 2“

Courseware: „Fundamentals of Local Area Networks - Part 2 / 2“

Book: „Abbreviations in Communications Technologies“

Book: „The OSI Model – simply explained“

Web:

Ronald Schlager´s Blog

www.ronaldschlager.com

http://www.ronaldschlager.com/eBooks23.htm


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Introduction to Local Area Networks