Download - Computer Networks -Introduction · Computer Networks -Introduction Wednesday, March 5,2014 Computer Networks: STS/MTA/Coursera/Cisco 4 Instructor: Ahmed Hussein Farah As an Employee:

Computer Networks

-Introduction

Wednesday, March 5,2014 Computer Networks: STS/MTA/Coursera/Cisco

Instructor: Ahmed Hussein Farah 1

In this Intro:

About the Instructor.

Course Contents.

Computer Networks

-Introduction



About the Instructor:

As an Instructor.

As an Employee.

As IT Consultant.

Computer Networks

-Introduction



As an Instructor:

More the 7 years instruction: in ComputerHardware,

Networking Administration and Software Engineering.

Teaching in Institutes and Universities: International

Horn University(2010-2011), SITCO(2005-2009),

SIDAM.

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As an Employee:

Currently as Network Security Administrator

About 8 years, I dealt with IT infrastructure such as Computers, Servers, Networking Devices, Switches, Routers, Firewalls….etc

I also administer, Configure, Secure and Install Windows Server/Client Network Controllers know as Domain Networks.

Train IT Officers in Regional Offices when we enforce or upgrade Network Systems….

Computer Networks

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As an IT Consultant:

I have my Own Consulting Company Since 2012

Its for IT Services which Include:

Cabling(Electricity/Telephones/Network),

PBX systems, VSATs,

Servers Deployment, Domain Network Setup,

Poin-to-Point and Multipoint Networks,

Security and Much more….

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General Uses of Networks:

Work:

– Email, file sharing, printing, …

Home:

– Movies / songs, news, calls / video, messaging, e-commerce,

Mobile:

– Calls / texts, games, videos, maps, information access …

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Uses of Networks

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For User Communication

From the telephone onwards:

– VoIP (voice-over-IP)

– Video conferencing

– Instant messaging

– Social networking

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For Resource Sharing

Many users may access the same underlying resource

– E.g., printers, search index, machines in the cloud

More cost effective than dedicated resources per user

– Even network links are shared via statistical multiplexing

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For Statistical Multiplexing

Sharing of network bandwidth between users according to

the statistics of their demand:

– (Multiplexing just means sharing)

– Useful because users are mostly idle and their traffic is busty.

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For Content Delivery

Same content is delivered to many users

– Videos (large), songs, apps and upgrades, web pages, …

More efficient than sending a copy all the way to each user

– Uses replicas in the network.

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For Computer Communication

To let computers interact with other computers

– E.g., e-commerce, reservations…

Enables automated information processing across different

parties

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To Connect Computers to the Physical World:

For gathering sensor data, and for manipulating the world

– E.g., webcams, location on mobile phones, door locks, …

This is a rich, emerging usage

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The Value of Connectivity

“Metcalfe’s Law” ~1980:

– “The value of a network of N nodes is proportional to N2”

– Large networks are relatively more valuable than small ones.

Bob Metcalfe

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Networks by Type:

WiFi (802.11)

Enterprise / Ethernet

ISP (Internet Service Provider)

Cable / DSL

Mobile phone / cellular (2G, 3G, 4G)

Bluetooth

Telephone

Satellite ...

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Networks by Scale:

Scale Type Example

Vicinity PAN (Personal Area Network) Bluetooth (e.g.,

headset)

Building LAN (Local Area Network) WiFi, Ethernet

City MAN (Metropolitan Area Network) Cable, DSL

Country WAN (Wide Area Network) Large ISP

Planet The Internet (network of all

networks)

The Internet!

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Internetworks and the Internet:

An internetwork, or internet, is what you get when you join

networks together.

– Just another network

The Internet (capital “I”) is the internet we all use

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Understanding Local Area Networks(LANs)

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Local Area Network

a “network” is two or more computers that exchange data.

A local area network (LAN) is a group of these computers that are

confined to a small geographic area, usually one building. Setting

up a LAN requires computers with network adapters, central

connecting devices to connect those computers together, and

a numbering scheme (such as IP addresses) to differentiate

from one computer to the next.

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Networks are used to exchange data. But Important reasons that organizations need networks? These reasons can be divided into four categories:

Sharing: Networks permit the sharing of files, databases, and media.

Communication: Networks are critical for email, instant messaging, and faxing capabilities.

Organization: Networks centralize data and make it more accessible, which increases the efficiency and speed with which this information can be accessed.

Money: A network should ultimately save a company money, often by aiding in the budgeting process and/or increasing productivity.

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Basic LAN documentation

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In the Figure, several hosts connect to the hub, including the following:

A server: A server is used to centralize data and share it (or serve it) with other computers on the network.

A PC (personal computer): A PC usually acts as a client on the network, most likely getting its information from the server. A PC can also store information locally.

A Mac (Macintosh) computer: As another type of client computer, a Mac can store information locally or get it from the server.

A laptop: This could be a PC or a Mac. Despite its portability, a laptop stores and accesses data the same way the other network computers do.

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Sunday, March 16, 2014 Computer Networks: STS/MTA/Coursera/Cisco


In this Week:

1. Network Card and Data Transfer

2. Networking Devices, UTP Cable, and Topologies.

3. LAN Architecture: (a) Peer-to-Peer, (b) Client Server,

( c) Distributed Computing and (d) Centralized

Computing.

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Network components and Terminology

Data

Node

Client

Server

Peer

Network adapter

Hub

Switch

Router

Media

Transport Protocol

Bandwidth

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1. Network Card and Data Transfer

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A network card: A network

adapter, also known as a

network interface card or

NIC,

NIC: is the device that

enables you to send and

receive data to and from

your computer.

NIC can be Wired or

Wireless.

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The network adapter might be integrated into the

motherboard or act as a separate device that connects to a

PCI slot, or perhaps a PC card slot or USB port.

An adapter can connect to the network by cable (wired) or

by air (wireless).

Network adapters also have a software component known as

a driver, which defines how the card will interact with the

operating system;

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View a Network Adapter

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Wireless Access Point

The wireless access point (WAP) acts as the central connecting device for the network

Wireless networks can consist of many types of devices other than traditional PCs:

Smart phones

PDAs

Tablet computers

Micro computers

PCs and laptops equipped with wireless network adapters can connect to these networks as well

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Wireless LAN Diagram:

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Wired LAN Documentation:

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Demos:

Device Manager Showing Network Adapters

Network Adapter Properties

IP Address

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Check the Driver, MAC(Physical) and IP your NIC.

1. Checking the Driver, Steps: Rclick Computer -> manage-

> device manager ->network adapters.

2. Check the MAC and IP address of your XP Computer,

Steps: start -> run-> cmd -> type: ipconfig /all -> enter.

3. Check the MAC and IP address of your Window7 PC,

Steps: start -> run-> cmd -> ipconfig /all -> enter.

4. Write down the MAC and IP of your PC.

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Serial Data Transfer

Serial data transfer is the transfer of one bit at a time—in

other words, transfer in a single-bit stream, like a one lane

highway

On the network cable, data travels in a single bit stream

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Data Transfer Rate

Data transfer rate is the maximum bits per second (bps) that

can be transmitted over a network

Rated in bits, and signified with a lowercase b (for example,

10 Mbps)

The lowercase b is for bits and an upper case B stands for

bytes (for example 10 MB)

Types of Transfers

Broadcast sends data to every other host on the network

Unicast sends data to a specific host

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IP Address

Most every computer and many other devices have an Internet Protocol (IP) address

An IP address uniquely identifies your device and the associated network and allows each device to send and receive information

A typical example of an IPv4 address would be 192.168.1.1

Every IP address is broken down into two parts by a subnet address

Network ID 192.168.1

Host ID 1

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Subnet Mask

The subnet mask is a group of four numbers that define what

IP network the computer is a member of.

All of the 255s in a subnet mask collectively refer to the

network portion, whereas the 0s refer to the host portion.

Type of

Address

First Octet Second Octet Third Octet Fourth Octet

IP Address 192 168 1 1

Subnet Mask 255 255 255 0

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Host

IP addresses are usually applied to your network adapter, but

they can also be applied to other devices like switches,

routers, and so on

The fact that a device or computer has an IP address is what

makes it a host

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LAN: Computers and other devices are connected using

copper-based twisted-pair cables or wireless equipment.

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Network Topology

A network topology defines the physical connections of hosts

in a computer network.

There are several types of physical topologies including:

Bus

Ring

Star

Mesh

Tree

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Star

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Mesh

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Ring

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Star Topology

Most Common topology

Each computer is

individually wired to a

central connecting device

(hub, switch or SOHO

router) with twisted-pair

cabling

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Mesh Topology

Every computer connects to every other computer; no

central connecting device is needed.

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Ring Topology

In a LAN environment,

each computer is

connected to the network

using a closed loop

Used by Token Ring and

Fiber Distributed Data

Interface (FDDI)

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Token Ring

A Token Ring network sends data logically in a ring fashion,

meaning that a token goes to each computer, one at a time,

and continues on in cycles

Namely, all computers in a Token Ring network are

connected to a central connecting device known as a

Multistation Access Unit (MAU or MSAU)

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Ethernet

Institute of Electrical and Electronics Engineers (IEEE)

standard (802.3) that defines how information is sent and

received between network adapters, hubs, switches, and

other devices

Ethernet is the de facto standard and is the most widely-

installed local area network technology

Common types of Ethernet include:

802.3u or Fast Ethernet that runs at 100 Mbps

802.3ab or Gigabit Ethernet

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Frames

Computers on Ethernet networks communicate via frames

A frame is a sequence of bits containing a detectable

beginning and end of a packet in the stream of bits

A frame is a data packet residing on Layer 2 of the OSI model

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Twisted Pair Cable

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Twisted-Pair Cable

the most commonly used cable type in local area

networks

relatively easy to work with, flexible, efficient, and fast

contains eight wires grouped into four twisted pairs,

typically blue, orange, green, and brown

The twisted wires reduce crosstalk and interference

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Twisted-Pair Cable with the Wires Exposed

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568B, 568A, and BOGB standards

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Twisted Pair Categories

Twisted-pair cables are categorized according to the

frequency at which they transmit signals and their data

transfer rate

Cable Type Speed

Category 3 (Cat-3) 10 Mbps

Category 5 (Cat-5) 100 Mbps

Category 5e (Cat-5e) 100 Mbps and 1000 Mbps+

Category 6 (Cat-6) 1000 Mbps+

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Tools For Twisted Pair Cables

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Twisted-Pair Patch Cable

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Types of Patch Cables

Straight through cable Most common type of patch cable

Used to connect a computer to a central connecting device like a switch

Crossover cable Used to direct connect similar devices without the use of a hub

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Patch Panel and RJ45 Wall Jack

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Network Documentation

Network documentation helps describe, define, and explain

the physical and logical method for connecting devices

The documentation phase occurs before a network is built,

or when changes are made to the network

Microsoft Visio is a tool that can be used to document

networks

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Hub

A Hub is the most basic

central connecting device

Hubs enable computers on

a network to communicate

A host sends data to the

hub. The hub sends the data

to all devices connected to

the hub

•

•

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Switch

Switches work the same

was as a hub, but they can

identify the intended

recipient of the data

Switches can send and

receive data at the same

time

•

•

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Router

Routers enable computers to communicate and allow communication between two networks – such as your home network and the Internet

This communications link between the one network and the other is where the LAN ends

192.168.1.1

Internet

24.136.72.110

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3. LAN Architectures

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Peer-to-Peer Networking

Peer-to-peer networking distributes applications or

workloads between computers

Peers are both service providers and service requestors

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Client/Server Networking

The client/server model is an architecture that distributes

applications between servers and client computers

Server: System that provides services such as Windows

Server 2008 R2

Client: Device that requests services such as Windows 7

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Distributed Computing

Distributive computing includes both client-server and peer-

to-peer networks

Every device or workstation has its own processing power

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Centralized Computing

Computing is done at a central location using terminals that

are attached to this main system

Mainframes are a powerful computer and the rest of the

devices connected to the computer are known as terminals

(or dumb terminals)

Each terminal consisted solely of a keyboard and display with

no processing power

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Servers

More powerful computers that provide centralized services:

File

Print

Database

Network controller

Messaging/Email

Web

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Client and Server Operating Systems

Client Operating Systems Server Operating Systems

Windows 8 Windows Server 2012

Windows 7 Windows Server 2008 R2

Windows Server 2008

Windows Vista

Windows XP

Windows Server 2003

Windows 2000 Professional Windows 2000 Server

Windows NT 4.0 Workstation

Windows ME/98/95

Windows NT 4.0 Server

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Summary of What We Covered in Week2:

Understand local area networks (LANs), including but not

limited to LAN elements, design, IP addressing, and LAN

types

Understand network topologies , including topologies such

as star, mesh, and ring; Ethernet architecture; and the client-

server and peer-to-peer networking models

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In Week3 (Next Class) We Will:

Cover All Important Concepts in Week1 and Week2.

Explain What you Should know and Remember in Past 2

weeks.

DON’T MISS.

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-Week3



In Week3 We Will:

Cover All Important Concepts in Week1 and Week2.

Explain What you Should know and Remember in Past 2

weeks.

Makin LAN Connections(UTP Cable).

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-Week3



In Week1:

Give 3 Examples for the general use of Networks in each of

the following:

1. Home.

2. Work.

3. Mobile (on the go)

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-Week3



Examples are:

Work:

– Email, file sharing, printing, …

Home:

– Movies / songs, news, calls / video, messaging, e-commerce,

Mobile:

– Calls / texts, games, videos, maps, information access …

Computer Networks

-Week3



Categorize the following uses of Networks as user

communication and Resource Sharing:

VoIP (voice-over-IP) , Sharing Printers, Video conferencing

Sharing Machines in the cloud, Instant messaging, Content

Delivery. Social networking, Statistical Multiplexing. ….

Computer Networks

-Week3



List 5 Different Types of Networks we use our daily

life

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List 5 of these networks…

WiFi (802.11)

Enterprise / Ethernet

ISP (Internet Service Provider)

Mobile phone / cellular (2G, 3G, 4G)

Bluetooth

Telephone

Satellite ...

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-Week3



List 4 Type of Networks by Scale with examples:

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Define LAN, what are the reasons for building Local Area

Networks?

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Reasons include:

Sharing Resources:

Example:……………………..

Communication:

Examples:………………..

Organization and User Management:

Examples:

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Define each of the Following:

Server.

PC.

Mac.

Terminal

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What is most important component(device) in our

Computers that enables to send and receive data.

What is the name of the software component, which defines

how the card will interact with the operating system

What are the Types of Network adapters.

Computer Networks

-Week3



What is the device we should have in order for Wireless

Devices to Communicate.

Computer Networks

-Week3



How data travels in the network cable?

What is the unit for the data transfer(speed) of the cable?

Define these types of data transfers:

Unicast and

Broadcast.

Computer Networks

-Week3



Why we assign IP address to a computer ?

What makes a device a host?

Computer Networks

-Week3



What are the Characteristics of these Network Topologies:

Ring

Star

Mesh

Computer Networks

-Week3



What are the 4 Colors(BOGB) of the UTP cable?

When we should use :

Straight-through cable

Cross-over Cable

Computer Networks

-Week3



Understand and Define the following:

Hub

Switch

Router

Peer to Peer Network.

Client/Server Network.

Computer Networks

-Week3



What are the Important Services that Servers Provide?

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-Week3



Main Services are

File

Print

Database

Network controller

Messaging/Email

Web

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-Week3



List three examples of each :

Client Operating System

Server Operating System

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-Week3



Making LAN Connections:

Straight-through and Cross-over UTP Cables:

Typically, when connecting different types of devices, use a

straight-through cable. And when connecting the same type

of device, use a crossover cable.

Computer Networks

-Week3



Straight-through UTP Cables

A straight-through cable has connectors on each end that are

terminated the same in accordance with either the T568A or

T568B standards.

Use straight-through cables for the following connections:

Switch to a router Ethernet port

Computer to switch

Computer to hub

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Crossover UTP Cables

To achieve this type of connection with a UTP cable, one end must be terminated as T568A pinout, and the other end terminated with T568B pinout,

To summarize, crossover cables directly connect the following devices on a LAN:

Switch to switch

Switch to hub

Hub to hub

Router to router Ethernet port connection

Computer to computer

Computer to a router Ethernet port

Computer Networks

-Week3



Computer Networks

-Week3



Build Straight-through and Cross-over Cable UTP

cables.

Computer Networks

-Week3



Computer Networks

-Week4-8

Wednesday, March 26, 2014 Computer Networks: STS/MTA/Coursera/Cisco


In these Weeks:

1. Standards.

2. OSI and TCP/IP Models

3. Understanding Internet Protocol & TCP/IP Tools

4. Network Services and Wide Area Networks

5. Network Infrastructure and Security

Computer Networks

-Week4



Standards

Standards are sets of rules that ensure hardware and software

released from different companies work together

Examples of Organizations that Coordinate Standards:

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-Week4



Examples of Organizations that Coordinate Standards:

International Organization for Standardization (ISO) – Federation of standards organizations from multiple nations

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-Week4



Open Systems Interconnection (OSI)

The Open Systems Interconnection (OSI) reference model is used to define

how data communication occurs between devices

The model is divided into 7 layers, each layer providing services to the layers

above and below

Layer Defines

Layer 7 – Application Layer Enables users and applications to access network services

Layer 6 – Presentation Layer Translates data into a common format

Layer 5 – Session Layer Establishes a communication session between devices

Layer 4 – Transport Layer Manages message fragmentation and reassembly

Layer 3 – Network Layer Manages data routing and creating sub networks

Layer 2 – Data Link Layer Provides error-free transfer of data frames

Layer 1 – Physical Layer Physical network media and signal methods

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-Week4



OSI Model Layers

Layer Protocol Data

Unit (PDU)

Application Data

Presentation Data

Session Data

Transport Segment

Network Packet

Data Link Frame

Physical Bits

Layer Protocol Data

Unit (PDU)

Application Data

Presentation Data

Session Data

Transport Segment

Network Packet

Data Link Frame

Physical Bits

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-Week4



Computer Networks

-Week4



OSI and TCP/IP MODEL

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OSI Model and Data Packet Units

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OSI , TCP Models and Protocols

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The two Groups of OSI Layers

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The lower layers

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The Transport layer can provide connection orientation

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Transport Layer Protocols (TCP and UDP)

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-Week4



User Datagram Protocol (UDP)

Applications that use UDP include:

Domain Name System (DNS)

Video Streaming

Voice over IP (VoIP)

Computer Networks

-Week4



Transmission Control Protocol (TCP)

Applications that use TCP are:

Web Browsers

E-mail

File Transfers

Computer Networks

-Week4



LAYERS OF NETWORK COMMUNICATION

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-Week4



Port Addressing

Computer Networks

-Week4



The Internet Assigned Numbers Authority (IANA) assigns

port numbers

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-Week4



TCP Ports

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-Week4



UDP Ports

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-Week4



TCP/UDP Common Ports

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-Week4



Three-way handshake Process:

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-Week4



Windowing

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-Week4



Layer 7 – Application Layer

Serves as a the window for users and application processes to

access network services

This layer is where message creation begins

End-user protocols such as FTP, SMTP, Telnet, and RAS work

at this layer

This layer is not the application itself, but the protocols that

are initiated by this layer

Computer Networks

-Week4



Layer 6 – Presentation Layer

This layer translates the data format from sender to receiver

in the various OSes that may be used

Presentation Layer concepts include: character code

conversion, data compression, and data encryption

Redirectors work on this layer, such as mapped network

drives that enable a computer to access file shares on a

remote computer

Computer Networks

-Week4



Layer 5 – Session Layer

The Session Layer manages session establishment,

maintenance and termination between network devices

Example: when you log on and log off

This layer controls the name and address database for the OS

Computer Networks

-Week4



Layer 4 – Transport Layer

This layer ensures messages are delivered error-free, in

sequence and with no losses or duplications

Protocols that work at this layer segment messages, ensure

correct reassembly at the receiving end, perform message

acknowledgement and message traffic control

The Transport Layer contains both connection-oriented and

connectionless protocols.

Computer Networks

-Week4



Connection Oriented Communications:

Require both devices involved in the communication

establish an end-to-end logical connection before data can be

sent

These communications are considered reliable network

services

Packets not received by the destination device can be resent

by the sender

Computer Networks

-Week4



Hello! I am a

PCHello! I am a

Server!

Ok, I will

watch for it!

I want to send

you something

important!

Connection Oriented Communications:

Computer Networks

-Week4



Layer 3 – Network Layer

Controls the operations of routing and switching information

to different networks

Translates logical addresses or names to physical addresses

Internet Protocol (IP) is a Network Layer protocol

Devices that work at the network layer are routers and IP

switches

Network Layer components: IP addresses, subnets

Computer Networks

-Week4



Packets

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-Week4



Layer 2 – Data Link Layer

Establishes, maintains, and decides how transfer is

accomplished over the physical layer and ensures error-free

transmission over the physical layer

Physical addresses (the hexadecimal address that is burned

into the ROM of the NIC), known as the MAC address

uniquely identify each hardware device work at the Data Link

Layer

Data Link Layer components: network interface cards and

bridges

Computer Networks

-Week4



Layer 2 Switches

Layer 2 switches are hardware-based and use the MAC

address of each host computer’s network adapter when

deciding where to direct data frames

Ports on the switch are mapped to the specific MAC address

of the device attached

Computer Networks

-Week4



Media Access Control Address

Network adapters on an Ethernet network have unique

Media Access Control (MAC) addresses

MAC addresses are unique identifiers assigned to network

adapters by the manufacturer

MAC address is written in hexadecimal

Computer Networks

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Layer 1 – Physical Layer

Defines the physical and electrical medium for data transfer

Physical layer components: cables, jacks, patch panels, punch

blocks, hubs…

Physical layer concepts: topologies, analog versus

digital/encoding, bit synchronization, baseband versus

broadband, multiplexing, and serial data transfer

Computer Networks

-Week4



Ethernet Standards

LAN standard providing a communication method for high speed data exchange among devices

Defined Physical and Data Link Layer

100BASE-T 100 for 100 Mbps BASE for baseband T for twisted-pair cabling

Baseband refers to the fact that devices on the network use digital signaling over a single frequency

Broadband systems use analog signaling over a range of frequencies enabling multiple channels over the same physical medium

Computer Networks

-Week4



Communications Subnetwork:

The communications subnetwork consists of layers 1 through

3

Physical

Data Link

Network

Regardless of what type of data transmission occurs in a

computer network, the communication subnetwork is used

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-Week4



3. Understanding Internet Protocol & TCP/IP

Tools

IPV4

Internet Protocol version 4 (IPv4) is the fourth version

of the Internet Protocol and the first version to be

widely deployed

IPv4 is a frequently used communications protocol and is

one of the core protocols for the Internet

IP resides on the network layer of the OSI model

Computer Networks

-Week4



IP Addresses

IP addresses consist of four octets (8-bits), each between 0 and

255.

Examples include:

12.5.24.2

127.0.0.1

192.168.3.54

208.32.56.232

In order for an IP address to function, there must be a properly

configured IP address and compatible subnet mask

Computer Networks

-Week4



Classful Network Architecture

The IPv4 classification system is known as a classful network

architecture broken down into five sections: Classes A, B, and C

are commonly used

An Class A IP address, the first octet is the “network” portion

Class IP Range

(1st Octet)

Default Subnet

Mask

Network ID / Host ID

A 0 – 127 255.0.0.0 Net.Host.Host.Host

B 128 - 191 255.255.0.0 Net.Net.Host.Host

C 192 – 223 255.255.255.0 Net.Net.Net.Host

D 224 - 239 N/A N/A

E 240 - 255 N/A N/A

Computer Networks

-Week4



Loopback Testing

The range for Class A is 0–127

The 127 network number isn’t used by hosts as a logical IP address

Instead, this network is used for loopback IP addresses, allowing

for testing

Computer Networks

-Week4



Usable Addresses

The first and last addresses cannot be used

For network 172.24.3.X

The 0 (in binary) for the host address is the entire network

172.24.3.0

The 1s (in binary) for the host address is the broadcast address

172.24.3.255

Computer Networks

-Week4



IP Conflict

IP conflicts occur when two devices have been assigned the same

IP address

Windows Error:

There is an IP address conflict with another system on the

network

If there is an IP address conflict, the devices will have problems

sending and receiving data

Computer Networks

-Week4



Public and Private Addresses

IPv4 addresses are further classified as either public or private.

Public IP addresses are ones that are exposed to the Internet

Devices connected to the Internet can potentially communicate

with them

Private IP addresses are hidden from the Internet and any other

networks

Usually behind an IP proxy or firewall device

Computer Networks

-Week4



Static and Dynamic Addresses

Static IP address are addresses that are manually assigned to a host

Dynamic IP addresses are more common than static IP addresses,

whereas they automatically obtain an IP address (and other IP

information)

Computer Networks

-Week4



Common TCP/IP Tools

command prompt

ipconfig

ping

Tracert

Netstat

Pathping

Computer Networks

-Week4



Command Prompt

The Windows command prompt is Microsoft’s version of a

command-line interface or CLI

Running the command prompt as an Administrator is also known

as running it in elevated mode

Tools can be run using the command prompt

Computer Networks

-Week4



Ipconfig

Displays the current configuration of the installed IP stack on

a networked computer using TCP/IP

The /all switch can be used to view additional details about

each adapter

Computer Networks

-Week4



Ping

verifies IP-level connectivity to another TCP/IP device by

sending Internet Control Message Protocol (ICMP) Echo

Request messages

A number of switches can accommodate different testing

scenarios

Can be used to test IPv4 and IPv6 connectivity

Computer Networks

-Week4



Ping Process

Hey, are you awake?

Why yes, yes I am...

Computer Networks

-Week4



Tracert

Determines the path taken to a destination by sending

Internet Control Message Protocol (ICMP) Echo Request

messages to the destination with incrementally increasing

Time to Live (TTL) field values

Used to “trace” a network path from sending to receiving

device

Useful if the local device is testing ok but connectivity can’t

be established

Computer Networks

-Week4



Tracert in Action

Hey, how do I get

there?

First you go

through me...Second you go

through me...

Then you re here!

Computer Networks

-Week4-8



4. Network Services and Wide Area Networks

Computer Networks

-Week4-8



DNS

Domain Name System (DNS) is a worldwide service that

resolves host names to IP addresses

DNS is part of the application layer of the TCP/IP reference

model

DNS servers use port 53 to accept name resolution requests

Computer Networks

-Week4-8



DHCP

Dynamic Host Configuration Protocol (DHCP) is a

client/server protocol that enables configured client

computers to obtain IP addresses automatically.

The IP information obtained might include the following:

IP addresses

Subnet masks

Gateway addresses

DNS server addresses

Other advanced options

Computer Networks

-Week4-8



The DHCP Server service provides the following

benefits:

Reliable IP address configuration

Reduced network administration

Computer Networks

-Week4-8



DHCP Server

Computer Networks

-Week4-8



How Does DHCP Server Word?

Computer Networks

-Week4-8



Wide Area Networks (WAN)

Wide area networks (WANs) connect multiple local area networks together

WANs connect multiple LANs that can include a home, school, or buildings

WANs enable network to function without concern to a location

WAN technologies can include:

Packet Switching: Devices transport packets via shared links

Leased Line: Dedicated point to point connection

Circuit Switching: Dedicated circuit path is created between end points (dial up)

ISDN, DSL, Broadband Cable, POTS/PSTN….

Computer Networks

-Week4-8



Routing

Routing is the process of managing the flow of data between

network segments and between hosts or routers

Data is sent along a path according to the IP networks and

individual IP addresses of the hosts

A router is a network device that maintains tables of information

about other routers on the network or internetwork

Computer Networks

-Week4-8



Static and Dynamic Routing:

A static route is a path that is manually configured and remains

constant throughout the router’s operation

A dynamic route is a path that is generated dynamically by using

special routing protocols

Computer Networks

-Week4-8



WAN Technologies:

Integrated Services Digital Network (ISDN) is a set of

communication standards enabling simultaneous digital

transmission of data, fax, voice and video .

ISDN can be broken down into two major categories:

Basic rate ISDN (BRI):

Primary rate ISDN (PRI):

Computer Networks

-Week4-8



DSL

Digital subscriber line (DSL) is a family of technologies that

provides data transmissions over local telephone networks

DSL allows for voice and data to be run over the same line

DSL uses higher frequency bands to transmit data

Computer Networks

-Week4-8



Broadband Cable:

Broadband cable is used for cable Internet and cable television

using the cable television network

It operates at a higher speed than DSL and rates can range from

384 kbps to 20 Mbps +

Computer Networks

-Week4-8



POTS/PSTN

POTS/PSTN stands for plain old telephone system/public

switched telephone network.

This is what we use now for “regular” phone lines, and it has been

around since the 1940s.

POTS/PSTN is now digital at the switching office and some

central offices, but there analog lines run to people’s homes.

Computer Networks

-Week4-8



5. Network Infrastructure and Security

Internet

Computer Networks

-Week4-8



Internet

The Internet is a worldwide system of connected computer

networks

Devices that connect to the Internet use the TCP/IP protocol

suite

The Internet contains a lot of information, resources and services:

World Wide Web (WWW) servers hosting content

Supporting infrastructure for email

Connectivity for peer-to-peer networks

Computer Networks

-Week4-8



World Wide Web

The World Wide Web (WWW) is an enormous system of

interlinked hypertext documents that can be accessed by using a

web browser

Interlinked hypertext documents can contain text, graphics and

videos

Currently, the World Wide Web is in a stage known as Web 2.0

Web 2.0 is an interactive type of web experience compared to the

previous version 1.0

Computer Networks

-Week4-8



An intranet is a private computer network or single Web site that

an organization implements in order to share data with employees

around the world

User authentication is necessary before a person can access the

information in an intranet

Ideally, this keeps the general public out, as long as the intranet

is properly secured

Computer Networks

-Week4-8



Accessing Company Data

A company can present information to different groups:

Intranet – For internal employees

Extranet – For partners

Web Server – For the public



Partner Public Remote Users

Computer Networks

-Week4-8



VPN

A virtual private network (VPN) is a connection between two or

more computers or devices that are not on the same private

network

In order to ensure that only the proper users and data sessions

cross to a VPN device, data encapsulation and encryption are used

A “tunnel’ is created, through the LANs and WANs that are being

used

/ISP

Computer Networks

-Week4-8



Firewalls

Firewalls are used to help protect a network from malicious attack

and unwanted intrusion

Computer Networks

-Week4-8



END OF THE COURSE:

Summary

Concepts you Should Know and Understand.