Networking Basics

Think Time
What is common to all these?

Types of Communication
Unicast is one to one communication

Multicast is one to group communication

Broadcast is one to all communication

 Similarly we have three ways of transmitting data.
 They are,
– Simplex
• Refers to transmission in only one direction where one party
is the transmitter and the other is the receiver
– Half duplex
• Refers to two-way communications where only one party can
transmit at a time
– Full duplex
• Refers to the transmission of data in two directions
simultaneously.

Think Time
OS
Hardware
???
Fully operational
system

Why Networking?
– Resource sharing
– Data sharing
– Performing complex operations by
distributing the work
– Accessing remote data and devices
– Interacting with other computers
– Accessing applications such as the World
Wide Web
Computers maybe networked for one or more of the following reasons –
Basically, means
that 2 or more
computers
communicate!

Think Time
Shall we define what a Computer Network is?

 A group of two or more computer systems that are linked together,
form, what is called a computer network
 Computers on networks are sometimes called nodes
– A node is a processing location in a network
– It can be a computer, or any other device such as a printer
– Every node has a unique address to locate it on the network
What is a computer network?

Crack the case!
Sheela, a florist, has a computer and printer in her shop. She has used them
successfully to
– keep sales records
– produce bills and vouchers
Sheela now needs two more computers for two additional billing counters.
You are the best networking consultant in town!
Sheela asks you – does she need to network her computers?

Crack the Case!
Task I
Could we prepare a questionnaire for Sheela to answer?
Help Sheela arrive at the need for networking
The answers should lead us to a Yes or No for Networking. Recall the
‗Why‘ of networking.
Purpose Sheela’s Need
Resource Sharing Printer? Internet Connection?
Data Sharing Sales across counters

Crack the Case!
Task II
Sheela has heard that there are two different ways that her network could
be set up, either as a ‗peer to peer‘ or as a ‗client - server‘ network.
Work with two other persons in your class to produce a short presentation
to describe the differences between ‘peer to peer’and ‘client - server’
networks.

Client Server Model
 A client places a request - service requester
 A server responds to client‘s requests - service provider

Client Server Model
The client/server model is a form of distributed computing where one
program, the client, communicates with another program, the server, for the
purpose of exchanging information

Peer to Peer Model
 A pure peer-to-peer network does not have the notion of clients or
servers, but only equal peer nodes that simultaneously function as both
"clients" and "servers" to the other nodes on the network.
 Peer-to-peer is a communications model in which each party has the
same capabilities

How of Networking
How do I network?
Peer to PeerClient Server
Topology Physical Components Framework
Cables
Connectors
Devices
Reference Models
Addressing
LAN Technologies

Topology
 The arrangement in which the nodes of a network are connected to each
other.
 It is usually a schematic description of the arrangement of a network,
including its nodes and connecting lines
 Topologies are either physical or logical
– The way that the workstations are connected to the network through
the actual cables that transmit data -- the physical structure of the
network -- is called the physical topology.
– The logical topology, in contrast, is the way that the signals act on
the network media, or the way that the data passes through the
network from one device to the next without regard to the physical
interconnection of the devices.

Classification based on Topology
 Bus Topology
– All computers are attached to a single continuous cable that is
terminated at both ends, which is the simplest way to create a
physical network
Terminator
Bus Topology Bus Failure

 Star Topology
– Each computer is connected to a central point by a separate cable.
The central point is a device known as a hub
– Is much more fault tolerant than a bus topology. This means that if a
failure occurs along one of the cables connecting to the hub, only
that portion of the network is affected, not the entire network
– New nodes can be added by running a single new cable
Star Topology

A
B
C
D
 Ring Topology
– Each computer is connected directly to two other computers in the
network.
– Data moves down a one-way path from one computer to another in
a single direction only
 Advantage:
– Laying the cables is relatively simple
Ring Topology

 Disadvantages of Ring Topology:
– A break in the cable results in the disruption of the entire network
– Adding new nodes can be tedious
– Since the data travels only clockwise, say, if machine A wants to
communicate with machine D, data can not be transferred if there is
a break in the loop
Failure of Ring Topology

 Mesh Topology – Fully Connected
– Each node of the network is connected to every other node with a
point –to-point link
– Makes it possible for a single node to communicate simultaneously
with all other nodes
Mesh Topology – Partially Connected
–Some nodes are connected to more than one other nodes through a
point-to-point link
–Reduces redundancy of the fully connected topology

Crack the Case!
Task III
Sheela is ready to proceed. You now need to research three different
network topologies (bus, ring and star) and extend the presentation you
prepared in Task II to describe the benefits and drawbacks of each one.
End your presentation with a recommendation to Sheela that includes
- The type of network topology and
- The reason behind the selection

Types of Computer Networks
Task III
Consider that Sheela now wants to go ahead and open a new store
altogether, away from the one that currently exists. If she wants to
network the two stores, what type of computer network should she be
looking for?

Classification based on Scale
 LAN – Local Area Network
– A network that is limited to a relatively small area such as a room or
a single building
– Sometimes called a single location network
Linksys 33

 MAN – Metropolitan Area Network
– A network that connects two or more LANs, but does not extend
beyond the boundaries or the immediate town or city
Chennai
Teynampet
Tambaram
Ambattur
T. Nagar

 WAN – Wide Area Network
– Generally covers a relatively broader geographic area
– Usually uses transmission facilities provided by common carriers
such as telephone companies

Think Time
Basic models of networks discussed –
Peer to Peer
Client Server
Topologies discussed –
Based on physical connection –
Star, Bus, Ring and Mesh
Based on physical extent –
LAN, MAN and WAN
Do the above topologies apply to both the basic models – P to P and
Client Server?

Ethernet
 Ethernet is the most common LAN (Local Area Network) technology in
use today.
 The first Ethernet standard, 10Base-5, ran over thick coaxial cable.
 A later standard, Ethernet 10Base-2, ran over a much thinner coaxial
cable.
 These two versions of Ethernet were colloquially known as thicknet and
thinnet.
Ethernet Standard Cable Specification
10Base-T Category 3 UTP
100Base-TX Category 5 UTP
1000Base-T Cat 5e UTP
1000Base-SX Optical Fiber

Token Ring
 A local area network (LAN) access method developed by IBM.
 Conforming to the IEEE 802.5 standard, Token Ring uses a token ring
access method and connects up to 255 nodes in a star topology at 4, 16
or 100 Mbps.
 All stations connect to a central wiring hub called the "Multistation
Access Unit" (MAU) using twisted wire cable.
Token Passing Token Ring Network

Physical Components of a Network

Transmission Media
Fiber opticCoaxial Cable
1. Thicknet
2. Thinnet
Twisted pair
1. Shielded
2. Unshielded
Medium
Wired Wireless
A medium is a carrier of something

Coaxial Cable
 Consists of a central copper core surrounded by an insulator, a braided
metal shielding, called braiding, and an outer cover, called the sheath or
jacket
 High bandwidth – Up to 400 MHz
 Max. used data rates – 100 Mbps
 High quality of data transmission
 Signal loss at high frequencies

Thicknet Coaxial Cable
 Is a rigid coaxial cable approximately 1-cm thick used for the original
Ethernet networks
 Also called ‗thick Ethernet‘, ‗yellow Ethernet‘ or ‗yellow garden hose‘
 Usually found an older networks
 IEEE designates Thicknet as ‗10Base5‘ Ethernet, interpreted as follows –
 ‗10‘ for transmission rate of 10 Mbps
 ‗Base‘ for baseband transmission
 ‗5‘ for the max. segment length of a Thicknet cable, which is 500 m

Thinnet Coaxial Cable
 Popular medium used in Ethernet LANs in the 1980s
 IEEE designates Thinnet as ‗10Base2‘ Ethernet, interpreted as follows –
• ‘10‘ for transmission rate of 10 Mbps
• ‗Base‘ for baseband transmission
• ‗2‘ for the max. segment length which is around 200 m
Thinnet

Twisted Pair Cable
 Consists of colour-coded pairs of twisted & insulated copper wires
 Used extensively in telephone cables
 Number of twists per unit length is known as ‗twist ratio’. More the
twist ratio, lesser the noise and therefore better the quality
 Is inexpensive, flexible, and easy to install
 One drawback to twisted-pair is that, because of its flexibility, it is more
prone to physical damage than coaxial cable
 All twisted pair cables fall into two categories –
 Shielded Twisted Pair (STP)
 Unshielded Twisted Pair (UTP)

Twisted Pair Cables
 Shielded Twisted Pair (STP)
– The insulated inner twisted pairs are surrounded by an additional
shielding usually made of metallic foil or braid
– The shielding acts as a barrier to external signals, thus reducing
noise
– The shielding may be grounded to enhance its protective effect
 Unshielded Twisted Pair (UTP)
– Does not contain additional shielding
– Advantage over STP is that it is less expensive
– Absence of shielding, however, makes it more prone to noise

Straight Through Cable
 It is a type of UTP cable
 The colour coding of the internal wires inside both ends of the cable are
similar
 Straight through cables could be used to connect dissimilar devices like
 Connecting a router to a hub or switch
 Connecting a server to a hub or switch
Pin Number Wire color Wire Becomes Pin number Wire color
Pin 1 Orange / White
Pin 2 Orange
Pin 3 Green / White
Pin 4 Blue
Pin 5 Blue/White
Pin 6 Green
Pin 7 Brown/White
Pin 8 Brown
1 1
2 2
3 3
6 6
Pin 1 Orange / White
Pin 2 Orange
Pin 3 Green / White
Pin 4 Blue
Pin 5 Blue/White
Pin 6 Green
Pin 7 Brown/White
Pin 8 Brown

Crossover Cable
 It is a type of UTP cable
 The colour coding of the internal wires inside both ends of the cable are
dissimilar
 Straight through cables could be used to connect similar devices like
 Connecting hubs to switches
 Connecting 2 hubs
Pin Number Wire color Wire Becomes Pin number Wire color
Pin 1 Orange/White
Pin 2 Orange
Pin 3 Green / White
Pin 4 Blue
Pin 5 Blue/White
Pin 6 Green
Pin 7 Brown/White
Pin 8 Brown
1 3
2 6
3 1
6 2
Pin 1 Green/White
Pin 2 Green
Pin 3 Orange/White
Pin 4 Blue
Pin 5 Blue/White
Pin 6 Orange
Pin 7 Brown/White
Pin 8 Brown

Straight Through vs. Crossover
The Transmit and Receive pins are shown above
Cross over cabling

Straight Through cable
Cross Over Cable

Similar Devices
Cross Over Cable
Dissimilar Devices
Straight through Cable
Hub / Switch PC
PCPC

UTP Types
Type Data Rate Usage
Cat 1 Up to 1 Mbps Telephone Line
Cat 2 Up to 4 Mbps Token Ring
Cat 3 Up to 10 Mbps Token Ring & 10 Base – T
Cat 4 Up to 16 Mbps Token Ring
Cat 5 Up to 100 Mbps Ethernet – 16 for Token Ring
Cat 5e Up to 1000 Mbps Ethernet
Cat 6 Up to 1000 Mbps Ethernet

IEEE Nomenclature
Standard Media Distance Connector
10 Base 2
10 Base 5
10 Base T
100 Base TX
Coaxial (Thinnet)
Coaxial (Thicknet)
CAT 3,4,5 UTP
CAT 3,4,5 UTP
185 M
500 M
100 M
100 M
BNC (British Naval
Connector)
AUI (Attachment Unit
Interface)
RJ 45 (Registered Jack – 45
Specific Wiring Sequence)
RJ 45
10 Base TTransmission rate Copper unshielded twisted pair
Base band signaling
Uses the entire bandwidth of
the transmission medium

Fiber Optic Cable
 Cables contain fiber lines in their cores instead of the usual copper wires
 Technique uses light pulses to transmit information through these optic
fibers
 Very high bandwidths of up to several Gbps
 Could be used for long distances covering hundreds of kilometers
 Provide very high bandwidth – up to 20, 000 MHz
 Low interference provides highly efficient transmission
 High costs are currently the only drawback

Media Dependent Interface X
Cross Over Cable
Straight through
Note: For uplink port Straight through and cross over cable can be used
Router Hub/Switch

Registered Jack (RJ)
 RJ-11 – Defined for
telephone connectors
 RJ-45 – Defined for
UTP connectors
RJ 45RJ 11

Devices in Network
 There are various network devices that are used to do networking.
 They are
 Repeater - Regenerates or replicates signals that are weakened or
distorted by transmission over long distances.
 Hub - Regenerates signals and broadcasts it out all of their ports
 Switch - Connects two or more network segments.
 Bridge - Breaks larger network segments into smaller network
segments.
 Routers - Connects different Subnets within a network or different
networks.

OSI (Open System Interconnect)
 It is a reference model designed by International Organization for
Standardization (ISO) in 1974
 OSI is a standard description for how messages should be transmitted
between any two points in a telecommunication network
 Its purpose is to guide product implementers so that their products will
consistently work with other products
Physical Layer
Datalink Layer
Netword Layer
Transport Layer
Session Layer
Presentation Layer
Application Layer

 The process of communication between two end points in a network can
be divided into layers, with each layer adding its own set of special, related
functions
 Each communicating user or program is at a computer equipped with
these seven layers of function
 So, in a given message between users, there will be a flow of data through
each layer at one end down through the layers in that computer and, at the
other end, when the message arrives, another flow of data up through the
layers in the receiving computer and ultimately to the end user or program
OSI (Open System Interconnect)

 The Physical layer defines all the
electrical and physical specifications for
devices
 Physical Layer defines techniques to
transfer bit stream to cable
Physical Layer
Hub and
Repeater
work in this
layer
ABC  0100111
Physical Layer
0100111  ABC0100111
Physical Layer
Physical Layer
Datalink Layer
Netword Layer
Transport Layer
Session Layer
Presentation Layer
Application Layer

 Data Link Layer receives end packages
raw data from the Physical layer into data
frames for delivery to the Network layer as
packets
Data link Layer is divided in to two layers:
LLC (Logical Link Control)
MAC ( Media Access Control)
Main function is Error detection Switch, Bridge
and NIC work
in this layer
Data Link Layer
Physical Layer
Datalink Layer
Netword Layer
Transport Layer
Session Layer
Presentation Layer
Application Layer

Data Link Layer
Logical Link Control (LLC):
Its functions include:
•The LLC works with the transport
layer by providing connection-
oriented and connectionless
services. It manages and creates
the communication link.
•It uses a calculated value called
CRC to check and thus control the
errors occurred during the
transmission of the bits across the
wire
Media Access Control:
The MAC sublayer has two
primary responsibilities:
•Data encapsulation, including
frame assembly before
transmission, and frame
parsing/error detection during and
after reception
•Media access control, including
initiation of frame transmission
and recovery from transmission
failure

Physical Layer
Datalink Layer
Network Layer
Transport Layer
Session Layer
Presentation Layer
Application Layer Network Layer is responsible for providing best
path for data to reach the destination
 Logical addressing is happening in this layer
 Network Layer translates logical network address
and names to their physical address (e.g. computer
name = MAC address)
Internet Protocol is an example of Network Layer
protocol
Router works
in this layer
Network Layer

 Transport Layer is responsible for reliable
delivery of data and error correction
 Provides acknowledgment of successful
transmissions; requests retransmission if some
packets don‘t arrive error-free
 Identifying Service, Multiplexing & De-
multiplexing and Segmentation happen in this
layer
 Examples of transport layer protocols
Transmission Control Protocol
 User Datagram Protocol
Brouter and
Gateway works
in this layer
Transport Layer
Physical Layer
Datalink Layer
Netword Layer
Transport Layer
Session Layer
Presentation Layer
Application Layer

Data
Breaking data into segments
This happens in the Transport Layer

 Session Layer is responsible for
establishing, maintaining and
terminating session
 Responsible for name recognition
(identification) so only the designated
parties can participate in the session
 Manages who can transmit data at a
certain time and for how long [Dialog
Control]
 Provides synchronization services by
planning check points in the data stream
if session fails, only data after the most
recent checkpoint need be transmitted
Gateway works
in this layer
Session Layer
Physical Layer
Datalink Layer
Netword Layer
Transport Layer
Session Layer
Presentation Layer
Application Layer

 The Presentation layer transforms data to
provide a standard interface for the
Application layer
 The Presentation layer relieves the
Application layer of concern regarding
syntactical differences in a message's data
representation within the end-user systems
 Following tasks are performed in
Presentation Layer
Encoding – Decoding
Encryption – Decryption
Compression – Decompression
Gateway works
in this layer
Presentation Layer
Physical Layer
Datalink Layer
Netword Layer
Transport Layer
Session Layer
Presentation Layer
Application Layer

The Application layer provides a means for
the user to access information on the network
through an application
 This layer is the main interface for the
user(s) to interact with the application and
therefore the network
Examples of application layer protocols
 Telnet
 File Transfer Protocol (FTP)
 Simple Mail Transfer Protocol (SMTP) and
 Hypertext Transfer Protocol (HTTP)
Gateway works
in this layer
Application Layer
Physical Layer
Datalink Layer
Netword Layer
Transport Layer
Session Layer
Presentation Layer
Application Layer

Computer B
6. Presentation
5. Session
4. Transport
3. Network
2. Data Link
1. Physical
Picture on web browser
Encoded picture
(JPG)
Initiates communications
(HTTP)
Communication PC to PC
(TCP)
IPAddress assignment
Network Interface
(NIC)
7. Application
6. Presentation
5. Session
4. Transport
3. Network
2. Data Link
1. Physical
Picture on web browser
Encoded picture
(JPG)
Initiates communications
(HTTP)
Communication PC to PC
(TCP)
IPAddress assignment
Network Interface
(NIC)
. . . 010100110
Layers Layers
Computer A
7. Application010100110
Communication between two computers

OSI Model
Gateway
HUB
Switch
Router

Data Travel in OSI
Data Encapsulation

Protocol
 A Protocol is an agreed-upon format for transmitting data between two
devices. The protocol determines the following:
 the type of error checking to be used
 data compression method, if any
 how the sending device will indicate that it has finished sending a
message
 how the receiving device will indicate that it has received a message
 Protocol suite is a compilation of many such protocols combined to
perform a set of tasks together and enable efficient communication over the
network.

TCP/IP Protocol Suite
 The TCP/IP Protocol Suite, is a layered abstract description for
communications and computer network protocol design
 It was built on the OSI Reference Model

Comparing OSI and TCP/IP
Although some of the layers in the TCP/IP model have the same name as
layers in the OSI model, the layers of the two models do not correspond
exactly.

Addressing
 Just as we use postal address, email address to communicate with our
friends, we do need an address to identify our computer in this web of
network.
 There are two different ways of identifying our machine in a network.
 MAC address and
 IP address

MAC Address
 The Media Access Control address (MAC) can be equated to the serial
number of the NIC. Every IP packet is sent out of your NIC wrapped
inside an Ethernet frame which uses MAC addresses to direct traffic on
your locally attached network
 MAC addresses therefore only have significance on the locally
attached network. As the packet hops across the Internet, its
source/destination IP address stays the same, but the MAC addresses
are reassigned by each router on the way using a process called ARP

MAC Address
 MAC addresses are usually written in one of the following two
formats:
00:13:21:0F:83:DF 00-13-21-0F-83-DF
 MAC address is a 48 bit address
 MAC address are 12 digit Hexadecimal {0-9} {A- F} Address

 The First Octet of the MAC Address is known as Group Unique -
00 : 13 : 21 : 0F : 83 : DF
 The Second and Third Octet of the MAC Address is known as
Organization Unique Identifier (OUI) –
00 : 13 : 21 : 0F : 83 : DF
MAC Address

 Any MAC address starts with 00 is known as Unicast address
00 : 13 : 21 : 0F : 83 : DF
 Any MAC address starts with 01 is known as Multicast
01 : 13 : 21 : 0F : 83 : DF
 Any MAC address starts with FF is known as Broadcast
FF : 13 : 21 : 0F : 83 : DF
MAC Address

Start  Run  Type winipcfg
For Windows 95, 98 & Me
Checking MAC Address

Select the Adapter
MAC Address

Click Start  Run Type cmd or command
For Windows 2000 & XP

Click Start Run  Type cmd or command  Type ipconfig /all
MAC Address
For Windows 2000 & XP

Type ipconfig / all
For Windows Vista

 Internet Protocol Address is given to the computer as an identifier to a
computer in a TCP/IP Network
 IP Address is also known as Logical Address
 IP Address works in Layer 3 (Network)
 Two versions of IP Addressing
IP Version 4 - 32 bit address (used currently)
IP Version 6 - 128 bit address
IP Address

To make it easier to work with these addresses, the 32-bit binary
number is broken into a series of decimal numbers.
To do this, split the binary number into four groups of eight binary
digits.
Then convert each group of eight bits, also known as an octet into its
decimal equivalent.
IP Address

Guna Complex, 6th Floor
Floor No.Building
Just as a street address has a standard two-part format (a street name and a
house number), each IP address is separated internally into two parts—a
network ID and a host ID
Parts of an IP Address
196 . 168 . 1 . 23
Network ID Host ID

Network ID:
The network ID, also known as a network address, identifies a single
network segment within a larger internetwork
All the systems that attach and share access to the same network have a
common network ID within their full IP address
This ID is also used to uniquely identify each network within the larger
internetwork
Host ID:
The host ID, also known as a host address, identifies a node within each
network
The host ID for each device identifies a single system uniquely within its
own network
Parts of an IP Address

 IPAddress is classified into three classes as follows
– Class A is written as N.H.H.H
– Class B is written as N.N.H.H
– Class C is written as N.N.N.H
Classification of IP addresses

• Class A 1 to 126
• Class B 128 to 191
• Class C 192 to 223
• Class D 224 to 239
• Class E 240 to 254
Widely Used
Multicast
Research & Development

Class First
Bits
First Byte
Values
Network ID
Bits
Host ID
Bits
Number of
Networks
Number of
Hosts
A
B
C
0
10
110
1 - 126
128 -191
192 - 223
8
16
24
24
16
8
126
16,384
2,097,152
16,77,214
65,534
254
IP Address Classes in a Nutshell

Click Start  Select Run  Type winipcfg  Select the Adapter
Windows 95, 98 and Me
Checking IP Address

Start  Run cmd or command  ipconfig
For Windows 2000, XP
Checking IP Address

There is no Start button in Vista instead
it is Windows Logo
Type cmd in the Start Search drop
down box
Checking IP Address
For Windows Vista

Command Prompt Window
Type ipconfig
For Windows Vista
Checking IP Address

Pull the Apple Menu 
Select ‗System Preferences‘
Click the network Icon
For Mac OS X
Checking IP Address & MAC Address

Select TCP/IP
Select
using
DHCPIP Address
Mac Address
For Mac OS X

Select the Go menu Select Applications
Click Utilities
For Mac OS X

Select Ethernet
Select
DHCP
IP
Address
Default Gateway
Checking IP Address
For Mac OS 9

Think Time
What does the marked area stand for in the following screen
shot?
MAC Address

Think Time
Identify the MAC address & IP address in the following screen
shot -
MAC Address – 00 : 11 : 11: B2 : DA : CD
IP Address – 192 . 168 . 1 . 1

Think Time
 What is the difference between MAC and IP address?
 Do you know how you can find your MAC address using
some command as you do with IP address?
 getmac

 A ‗subnet‘ is a portion of the computer network that shares a common
address component
 Dividing a network into subnets is useful for both performance and
security reasons
 A ‗subnet mask‘ is used to determine what subnet an IP address
belongs to
Subnet Mask
Subnet Masking

 Subnet Mask is to differentiate the Network ID and Host ID
 Two numbers reserved for Subnet Mask i.e. 0 & 255
 0 Denotes Host and 255 Denotes Network
Class Default Subnet Mask
Class A is written as 255.0.0.0 N.H.H.H
Class B is written as 255.255.0.0 N.N.H.H
Class C is written as 255.255.255.0 N.N.N.H
Subnet Mask

IPAddress : 10.20.50.26 Subnet Mask : 255.0.0.0
For this IP Address :
Network ID is : 10.0.0.0
First Valid IP Address : 10.0.0.1
Last Valid IP Address : 10.255.255.254
Broad Cast Address : 10.255.255.255
Number of hosts = (256x256x256) -2
Subnet Mask

IPAddress 172.26.28.36 Subnet Mask : 255.255.0.0
For this IP Address,
Network ID is :
First Valid IP Address :
Last Valid IP Address :
Broad Cast Address :
Number of hosts =
172.26.0.0
172.26.0.1
172.26.255.254
172.26.255.255
(256x256) – 2
Subnet Mask

For this IP Address:
Network ID is : 192.168.0.0
First Valid IP Address : 192.168.0.1
Last Valid IP Address : 192.168.0.254
Broad Cast Address : 192.168.0.255
Number of hosts = (256) – 2
IPAddress 192.168.0.152 Subnet Mask 255.255.255.0
Subnet Mask

 Private –
– A set of IP addresses reserved by the Internet Standards group
for private usage. It provides high security to the network.
 Public
– All the other IP addresses come under Public IP addresses, which
can be easily accessed by everyone.
 Static
– An IP address that remains the same every time the computer
logs on to the Internet.
 Dynamic –
– Is assigned to a computer every time it connects to the Internet
and is different every time.
IP addresses can be -

 IP addresses are publicly registered with the Network Information Centre
(NIC) to avoid address conflicts
 Computers on private TCP/IP LANs however do not need public
addresses
 For this reason, the NIC has reserved certain addresses that will never be
registered publicly. These are known as private IP addresses
 The Internet Assigned Numbers Authority (IANA) has reserved the
following three blocks of the IP address space for private internets (local
networks):
10.0.0.0 - 10.255.255.255
172.16.0.0 - 172.31.255.255
192.168.0.0 - 192.168.255.255
Private IP Address

Class Network Address
A 10.0.0.0 through 10.255.255.255
B 172.16.0.0 through 172.31.255.255
C 192.168.0.0 through 192.168.255.255
Private IP Address Range
Private IP Address

Think Time
Please look into your terminals
Classify the IP addresses into Private and Public

Static IP Address
 A permanent IP address that is assigned manually to a computer in a
TCP/IP network.
 With a static IP address, other Internet users always know the identity of
the computer and can easily connect with it.

Start Run Type winipcfg Select the Adapter
Click Release
Assigning Static IP Address

 Assign the IP address. After you have assigned the static
IP address you can never release or renew it

Click Properties
Select IP Address TABSelect TCP/IP

Select this Enter the IP address
Note: If assigning Static IP, Global DNS has to be assigned

Select ‗Internet Protocol
(TCP/IP)‘
Click Properties
Select ‗Use the following IP
Address‘
Note: For static IP, Global DNS must be assigned
For Windows 2000, XP

Assigning Static IP address
Go to Network Connection
Status & select Properties
Click Continue
Contd.
For Windows Vista

For Windows Vista

Select Use the following IP address Click OK
For Windows Vista

Type ipconfig to check the IP address
For Windows Vista

Assigning static IP Address
Type drakconf  Select Network & Internet  Manage connections
For Mandrake Linux

 Select TCP/IP Select Static
For Mandrake Linux
Assigning static IP Address

Think Time
• Assume we have 100 computers networked as a LAN. Each
computer should be assigned an IP address.
• Do you think this task can be done manually?
• What are the possible difficulties or issues that might arise
here?

Dynamic Addressing
 A temporary numeric identification assigned to a node in a TCP/IP
network.
 ISPs typically assign dynamic addresses to the Internet connections of
their residential and small business customers, which are less expensive
than static addresses.
 That means the IP address to the outside world in a cable or DSL
modem may change every month, every day or even every hour
 When computers and devices in the network are turned on, they are
assigned an IP address by a DHCP server.

Releasing an IP Address
Start Run winipcfg
Select the Adapter
Click Release

Start Run winipcfg Select the adapter
Click Renew
Renewing an IP Address

Loopback Address
 Loop Back Address:
The IP address 127.0.0.1 is used as the loop back address.
This means that it is used by the host computer to send a message back to
itself. It is commonly used for troubleshooting and network testing

Loopback Address
 Loop Back address is also known as semi broad cast address
 Range of Loop back address : 127.0.0.1 to 127.255.255.254
 Any IP address starts with 127 is known as loop back address
Click Start Run  Type cmd  Ping 127.56.26.36

 Type ping 127.0.0.1 and press Ctrl+z to stop the utility
For Mandrake Linux
Loop Back Address Test

Broadcast Address
 Messages that are intended for all computers on a network are sent as
broadcasts
 These messages always use the IP address 255.255.255.255
 Any IP Address with last Octet as 255 is known as broadcast address for
that particular network E.g.: 10.255.255.255
 The IP address of 0.0.0.0 is used for the default network

Think Time
Please look into your terminals
Match the IP addresses with their corresponding names

IP configuration - Error
The error message ‗The operation failed as no adapter is in the state
permissible for this operation.‘, indicates that static IP is assigned to
the computer and therefore can not be released
Error Message – IP release

Windows IP Configuration - Errors
If the network card is disabled the computer will display the
message ‗Windows IP Configuration‘ when you enter the
command ipconfig

If TCP/IP is unchecked, the computer will display the message
Windows IP Configuration, when you type the command ipconfig
Note: You cannot uninstall TCP/IP in Windows XP
Windows IP Configuration - Errors

Media Disconnected Error
If the network cable is unplugged or any damage in the cable the
command prompt window will display as media disconnected if we type
ipconfig. This is applicable only for Windows XP.

Cable Disconnected Error
If the network cable is unplugged or any damage in the cable the
command prompt window will display as cable disconnected if we type
ipconfig. This is not applicable for Windows XP.

Think Time
I have connected a PC to a hub/switch. I type ipconfig in the command
prompt. What will be the IP address? What will I get if I release /renew
the IP address?
Solution
If the static IP is assigned to the PC, then IP address will be displayed if
you type ipconfig. If no IP address has assigned to the PC the result will
be 0.0.0.0. If you try to release and renew the IP address will be 0.0.0.0

1. I have a desktop which uses Win98. I have installed a Linksys fast
Ethernet adapter. When I type winipcfg, I do not find the Linksys
adapter listed in the IP configuration window. What is the problem?
2. I have plugged the Linksys NIC card in the PCI slot. After I restart my
PC, I do not get found new hardware message. What troubleshooting
should I do?
Think Time

Ping
 Ping is a utility used to check IP
connectivity between two hosts
 Ping command works based on
Internet control message
protocol (ICMP)
 Ping stands for Packet Internet
Gopher

Ping test
Click ‗Start  ‗Run‘  Type ‗cmd‘ or ‗command‘  Type ping
<host name>

Loop back address test
Click ‗Start‘ ‗Run‘ Type ‗cmd‘ Type ‗ping 127.0.0.1 ‗
Note: 127.X.X.X is used for loop back address

Continuous ping
Type ‗ping <host name> –t ‗ in the command prompt
To stop continuous ping press Ctrl+C
Note : Ping 127.X.X.X is to check whether TCP/IP bindings installed
properly. This command is not to check NIC card is working properly or not

Note : Ping 127.X.X.X, Ping localhost and Ping loopback are the same
Continuous ping

Select ‗Network Utility‘
Select Ping Tab
Click ‗Ping‘
Performing Ping Test
For Mac OS X

Trace Route
 Trace route is a utility that shows you the route through the Internet
between your computer and a specified destination computer. Also it
displays the amount of time each hop takes. Trace route is a handy
tool to find out where problems may lay along the path between one
computer to another
 Maximum Number of Hop Count displayed is 30
 It also shows the response times in milliseconds for each hop
 To perform a trace route the following command should be typed in
the command prompt as ―tracert‖ followed by website address

Performing Trace Route
Click ‗Start‘ Run  Type ‗command‘ Type ‗tracert <host name>‘

For Mac OS X

Select the ‗Apple‘ Menu
Click Control Panel
Select TCP/IP

Latency
The amount of time it takes a packet to travel from source to destination.
Together, latency and bandwidth define the speed and capacity of a
network
Packet

Latency
My PC
Intranet Site
Website
ms = Millie Second
Latency can be found using the ―Ping‖ command

Time To Live (TTL)
 It determines the maximum amount of time an IP packet may live in the
network without reaching its destination
 It is effectively bound on the number of routers an IP packet may pass
through before being discarded
 The ―Ping‖ and the ―Traceroute‖ utilities both make use of the TTL value
to attempt to reach a given host computer or to trace a route to the host

Address Resolution Protocol
 Address Resolution Protocol is a TCP/IP protocol used to convert an IP
address into a physical address (MAC Address)
 A host wishing to obtain a physical address broadcasts an ARP request
onto the TCP/IP network
 The host on the network that has the address in the request then replies
with its physical hardware address
 ARP belongs to Layer 3

192.168.2.28
192.168.2.36
IP: 192.168.2.36 = ???
I need the
Ethernet address
of 192.168.2.36

 MAP IP = MAC Address
192.168.2.28
IP: 192.168.2.36 = Ethernet : 00-16-17-18-42-8A
192.168.2.36
IP: 192.168.2.36 = ???
I heard that broadcast.
The message is for me.
Here is my Ethernet
address
I need the
Ethernet address
of 192.168.2.36

ARP Table

 Used by a host to discover its IP address
 A protocol, which provides the reverse function of ARP
 RARP belongs to Layer 3
 RARP is used to resolve an IP address from a given hardware address
(MAC address)
Reverse Address Resolution Protocol

Ethernet: 00-16-17-18-42-4B IP = ???
What is
my IP
address?

 Map MAC = IP address
Ethernet: 00-16-17-18-42-4B = IP: 192.168.2.56
Ethernet: 00-16-17-18-42-4B IP = ???
What is
my IP
address?
I heard that
broadcast.
Your IP
address is
192.168.2.56

DNS (Domain Name System)
 DNS is an internet service that translates domain name
(www.slashsupport.com) to IP Address
 Internet is based on IP Address whereas domain names are
alphabetic, every time you use an domain name, DNS translates in to
corresponding IP Address
 For example www.slashsupport.com to 216.148.62.220
DNS Name Resolution

.com .edu
.gov .org
DNS Name Resolution
.co
m
yahoo.com
google.com
msn.com
css.com
espnstar.com
www.msn.com
Web Server
Web ServersRoot Servers
www.msn.comRequest type
Web server
Root Server
207.68.172.246

PC connected to Internet sending a request to website www.slashsupport.com
DNS Server -
resolves domain
name to
IPAddress
www.slashsupport.com
resolved to IP
216.148.62.220
DNS

Note : If the IP address is dynamic, will be able to get the same webpage next time
DNS

How to check DNS functionality?
 The ―nslookup‖ tool to look up information in the DNS. Basically DNS
MAPS domain names in to IP addresses
 To resolve an IP address in to domain name and domain name in to IP
address ―nslookup‖ command is used.

Select the adapter and click ‗More Info‘
Checking DNS

Assigning Global DNS
Select TCP/IP Select Enable DNS

Click Add Click OK
For Windows 95, 98 & Me (contd.)

On clicking ‗OK‘ the user is prompted to restart the computer

Note: If the Host name is not entered the above error message appears on clicking
‗OK ‗.

Flushing the DNS
 When a computer visits a website for the first time, it stores the
website's DNS information in DNS cache
 The next time the computer visits a website, it looks in the cache to
see if the website's information is present to use
 This can cause problems if the website's DNS information has
changed since the computer's last visit
 Flushing the cache removes all the information stored in cache,
forcing the computer to find the new DNS information for the
website

Flush and Register DNS
Type ipconfig /flushdns
Type ipconfig /registerdns

Think Time
 A customer wants to assign global DNS in his computer. He
particularly requests for written instructions. Can we think of
minimum number of simple, and short steps?
Lets get together in groups!

Windows Internet Naming Service (WINS)
192.168.2.26
192.168.2.28
192.168.2.56
192.168.2.57
9C26
9C28
9C56
9C57
IP AddressHost Name
Local Machine (LM) host
IP : 192.168.2.26 IP : 192.168.2.28 IP : 192.168.2.56 IP : 192.168.2.57
WINS Server
9C26 9C28 9C56 9C57
9C26 trying to reach 9C56
WINS used in Intranet
WINS Server IP : 192.168.2.100

Request Timed Out
 The ping command timed out because there was no reply from the
host. The source and the destination computer are in the same network
 When Ping command is initiated from one system to the other in a
network if the firewall is enabled on the Destination System Request
Timed Out error will Pop up

Destination Host Unreachable
This error occurs when the host that is pinged is in a different network.
Destination and the source belong to the different network

Request timed out vs. Destination Host Unreachable
IP : 192.168.1.53
Mask : 255.255.255.0
D.G : 192.168.1.1
IP : 192.168.0.8
Mask : 255.255.255.0
D.G : 192.168.0.1
IP : 192.168.2.56
Mask : 255.255.255.0
IP : 192.168.1.36
Mask : 255.255.255.0
Hub/Switch
Hub/Switch

Destination Net Unreachable
Destination Net Unreachable message is one which a user would usually
get from the Default Gateway when it doesn't know how to get to a
particular net work

Destination Host Unreachable vs. Destination
Net Unreachable
Cable/DSL Modem
WAN Side
LAN Side
Internet
Note: Since the Router is not able to pass the WAN interface it
is giving the reply from LAN interface
IP : 192.168.2.168
Mask : 255.255.255.0
IP : 192.168.1.192
Mask : 255.255.255.0
Hub/Switch
Router

Unknown Host
 If the DNS resolution is not happening the computer will display as
Unknown host
 Global DNS has to be assigned to fix this issue

Command Prompt Error
If the static IP Address is assigned to the computer and if we tried to renew
the IP Address it will display as ―Operation failed as no adapter is in the state
permissible for this operation‖

Some Error Codes
Direct Firewall or PIX or Norton Internet Security Installed (NIS)
Error Code 28 (Command Prompt)
Anti Spy Ware or Zone Alarm in the Computer
Error Code 65 (Command Prompt)

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