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Agenda

Introduction to Networking

Why Networking

Components

Topology

Network Types


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Networking: What & Why?

Networking :connect dispersed resources: people, computers, sites, nodes, offices, information

bases, databases etc.

People Network develops via contacts

Rail/ Airline Network links train stations/ airports

Computer Network links computers e.g. PCs

PURPOSE: collect, organize, protect, share, disseminate anduse INFORMATION on resources, for better business

operations E.g. Install/configure software on servers/ clients

Monitor/ control access; backup/restore

Critical Business Tool


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Networks of Computers

Computing nodes (PCs, Minis, Mainframes) Data Server node

Processing/ Application/ Web Server node

Client node

Network node

Network links can span distances at 3 levels: LAN: Local Area Network (building or campus)

MAN: Locality or City-wide network

WAN: Across country or continent(s)

Each technology has its own distance or size constraint Speed or reliability is assured only within those limits:

Signal Propagation

Signal Attenuation

Signal Bounce


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Effectiveness

All businesses need to work at high speed

Good Decisions need secure, accurate and timely

information internal & external

Messages from a Sender must reach Receiver with

following qualities:

Availability

Reliable Accuracy

Appropriate Timeliness

Integrity/ Uncorrupted

Confidentiality

Authenticated Source

Basic Networking

Secure Networking


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Agenda


Why Networking

Components Node Types

Network Types

Topology

Network Types


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Nodes - Providers or Consumers

Pure Consumers Clients

WinME

Pure Providers Servers

WinNT Server 4.0, Novell NetWare

Hybrids Peers

WinXP, Win95, MacOS Sender ReceiverMedium

Protocol

Message Message

Components of Communication System


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Network Types

Server Based (Client-Server)

Servers provide shared services

Clients find required resources and request services

Peer Network

Workgroups; no central security

Hybrid Network

Have all types of Nodes, along with domains and

workgroups


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Server Based Network

Also called Client-Server Servers: share secure services (files, DB, printer)

Run a NOS e.g. Novell NetWare, RedHat Enterprise Linux

Pros:

Central sharing of applications, hardware, files User-friendly, managed security (rules/ policies)

E.g. Windows Server 2003 Domains with Active Directory

Optimized/specialized servers are more efficient

Cons: Expensive HW, NOS, Licenses

Server failure renders a network unusable.

Need dedicated Administrator(s).

Dedicated HW and specialized SW add to the cost.


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Peer Network

Workgroups

Ad hoc; no central security/ login

Resource sharing controlled by users

Protected by separate passwords Unprotected (no password)

accessible from any node

Pros:

Easy/cheap to install/ setup; Good for


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Hybrid Network

Combined features (most modern enterprise LANs)

Have all types of Nodes, along with domains and workgroups

Servers provide shared application, authentication, email, backup

and license services

Selective sharing of folders and resources (printers, files, ftp,databases) to limited groups of colleagues (peer-to-peer or

workgroup-based)

PRO: Best of both worlds

CON: Shared resources on Peer nodes are at risk onsecurity, backup and performance concerns


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Server Types

These need HW in tune with user load :

Application Server

Directory Server (Domain Controller ) Fax Server

File and Print Server

Database Server

Mail Server (Microsoft Exchange server of 2000/2003) Web Server

Communication Server


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Eligibility to be a Server

Faster CPUs

More memory

Larger disk drives

Extra peripherals

Most importantly, server OS which are designed to handle

multiple requests for shared resources expediously.

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Windows Server 2008

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Component Requirement

Processor Minimum: 1 GHz (x86 processor) or 1.4 GHz (x64 processor)

Recommended: 2 GHz or fasterNote: An Intel Itanium 2 processor is required for Windows Server

2008 for Itanium-Based Systems.

Memory Minimum: 512 MB RAM

Recommended: 2 GB RAM or greater

Maximum (32-bit systems): 4 GB (Standard) or 64 GB (Enterprise

and Datacenter) Maximum (64-bit systems): 32 GB (Standard) or 1 TB (Enterprise

and Datacenter) or 2 TB (Itanium-Based Systems)

Available Disk Space Minimum: 10 GB

Recommended: 40 GB or greater

Note: Computers with more than 16 GB of RAM will require more

disk space for paging, hibernation, and dump files.

Drive DVD-ROM drive

Display and

Peripherals

Super VGA (800 x 600) or higher-resolution monitor

Keyboard

Microsoft Mouse or compatible pointing device


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Selecting Type of NetworkAre ALL of these TRUE:

a. # Users expected < 8

b. Distances small; single LAN segment

c. No specialized servers or control

d. Limited budgetNOYES

Server BasedPeer-to-Peer

MAN Links WAN Links

Multiple

Sites? Across CitiesIn a city

NO

No MAN/WAN Links

Is ANY of these TRUE:

a. # Nodes expected > 100

b. Certain groups need security barrier

c. Spans not confined in floors or buildings

LAN Internetworking

YESNO


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Exercise

A company operates its two branches, one in Bangalore and

other in Chandigarh. The company wants the two locations to

share a single database so that managers at each facility can

exchange work orders and monitor inventory on demand.

Users need some control over resources, but the companyalso wants network faxing and dial-up services at each

location.

Would you choose a peer-to-peer network or server basednetwork, or a combination of both? Why?

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Agenda


Why Networking

Components Topology

Network Types


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Topology

Physical Layout of nodes, media and resources (cabling,access points, towers)

Logical Layout path taken by the signal/ data elements

Topology affects the performance and security parameter

Topology affects decisions like type of equipment to purchase

and best approach to NW management

Simple to complex:

Pt-to-Pt (e.g. hotline)

Linear Bus

Ring

Star

Others (Switched, Extended Star, Mesh, Hybrid)


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Linear Bus

Easy to install/ maintain (


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Logical Bus

The logical topology on a Physical Bus

Can also be used on Physical Star

Nodes are Passive(listening, not forwarding signals)

FCFS scheduling of transmitters

Obsolete due to performance and reliability

concerns A nodes signal reaches all other nodes (e.g.

via Hub); only the addressee responds


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Ring Topology

Active: nodes retransmit signals

SPOF avoided by dual rings

FDDI, SONET are physical rings

Token Ring (logical) runs on PhysicalStar

Fair sharing; no monopolyUse: hi-traffic, time-critical apps as nocomputer can monopolize thenetwork.

Any Node or Link is a SPOF

Nodes linked in a Ring no collisions or terminators

Data runs clockwise/ counterclockwise


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Star Topology

All nodes link to a central hub, switch,concentrator

Uses more cable

Hub can be a SPOF

Common in home, SME LANs

Physical Star is popular choice to

support Logical Bus/Ring

Even if one link or node fails, rest ofnetwork functions fully

Hub or Switch is a SPOF;

But no Node or Link is.


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Extended Star

All nodes link to a sub-central device, which inturn connects to a central unit

Suitable for larger LANs and MANs to preventdegraded signals

Multiple POF; but partial impact Common in enterprise/ campus LANs

Usually supports switched signaling

Even if one link or node fails, rest of network

functions fully

Any Hub or Switch is a POF;

But no Node or Link can halt

entire network.


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Mesh Topology

Adds links for Fault-tolerant operation Messages can take any of several possible paths

from source to destination

FULL: Redundant links to all devices Most expensive

common in WANs, core cross-country networkoperator backbones

PARTIAL: only a few alternate routes, forcritical nodes common in large enterprise and service provider

metro backbones

E.g. Internet


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Hierarchical (Tree) Topology

Integrates multiple stars onto a ROOT. (Bus/star hybrid ) Simple form: Only hub devices connect directly to the tree

bus, and each hub functions as the "root" of a tree of devices.

Supports future expandability much better than a bus (limited

number of devices due to the broadcast traffic) or a star (limited by thenumber of hub connection points) alone.

ROOT can be a SPOF


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Common Logical Topologies

Physical Star can be used to implement:

Logical Bus (Star Bus) Nodes signal is retransmitted by hub to all

other nodes; only the addressee responds

One transmitter at a time; FCFS

Smart hub can remove a faulty node fromnetwork

Logical Ring (Star Ring) Uses Concentrator or MSAU

A logical token circulates sequentially to allnodes


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Wireless Networks

First wireless voice transmission (1915) in US

Wireless telephony Analog (1970s) started in Nordic countries

Digital (1984+) in Europe (standards) and US (no standards)

Usual Topologies in data networks: Point-to-Point (ad-hoc)

Star (Access point)

Extended Star

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