Network communication and prtocols

NETWORK COMMUNICATION
AND PRTOCOLS
AUTHOR :: ABDULLAHJAN
MSCS
COMPUTER SCIENCE LECTURER IN PAK DEGREE COLLEGE NOSHERA

COMPUTER NETWORK
 A network is a collection of computers or nodes that communicate with each other
on a shared network medium. A computer network is a collection of two or more
connected computers to share the resources and data. When these computers are
joined in a network people can share different files and devices such as modem
printer and tape drivers.

DATA COMMUNICATION
 Exchange of data between two devices via some form of transmission medium
such as a wire cable.
The effectiveness of data communications depends
upon three fundamental characteristics:
Delivery: Deliver data to the correct destination.
Accuracy: Deliver the data accurately.
Timeliness: Deliver data in a timely manner. Real-time
transmission requires timely delivery [without significant
(important) delay].

Five components of data communication
 Message: Data to be communicated or message is the data or information that is
to be transmitted . Message can be number , video , text or any combination of
these
 Sender : is a device that sends the message
 Receiver: is the device which receives transmitted message
 Medium: Transmission medium is the physical path by which a message travels
from sender to receiver
Twisted-pair, coaxial cable, fiberoptic cable or radio waves.
 Protocol: Set of rules that govern data communications.

Modes of communication
 Simplex:
 In simplex mode, the communication is unidirectional, as on a one-way street. Only
one of the two devices on a link can transmit; the other can only receive (see Figure
1.2a). Keyboards and traditional monitors are examples of simplex devices. The
keyboard can only introduce input; the monitor can only accept output. The
simplex mode can use the entire capacity of the channel to send data in one
direction.

 Half duplex:
 In half-duplex mode, each station can both transmit and receive, but not at the
same time. : When one device is sending, the other can only receive.
 The half-duplex mode is like a one-lane road with traffic allowed in both directions.
When cars are traveling in one direction, cars going the other way must wait. In a
half-duplex transmission, the entire capacity of a channel is taken over by
whichever of the two devices is transmitting at the time. Walkie-talkies and CB
(citizens band) radios are both half-duplex systems. The half-duplex mode is used
in cases where there is no need for communication in both directions at the same
time; the entire capacity of the channel can be utilized for each direction

 Full-duplex:
In full-duplex mode(also called duplex), both stations can transmit and receive
simultaneously(happening at exactly the same time). The full-duplex mode is like a two-way
street with traffic flowing in both directions at the same time. In full-duplex mode, signals
going in one direction share the capacity of the link: with signals going in the other direction.
This sharing can occur in two ways: Either the link must contain two physically separate
transmission paths, one for sending and the other for receiving; or the capacity of the channel
is divided between signals traveling in both directions. One common example of full-duplex
communication is the telephone network. When two people are communicating by a
telephone line, both can talk and listen at the same time. The full-duplex mode is used when
communication in both directions is required all the time. The capacity of the channel,
however, must be divided between the two directions

Synchronous transmission
 In synchronous(existing or occurring at the same time ) transmission, the bit
stream is combined into longer "frames," which may contain multiple bytes. Each
byte, however, is introduced onto the transmission link without a gap between it
and the next one. It is left to the receiver to separate the bit stream into bytes for
decoding purposes. In other words, data are transmitted as an unbroken string of
1s and Os', and the receiver separates that string into the bytes, or characters, it
needs to reconstruct the information.
 In synchronous transmission, we send bits one after another without start or stop
bits or gaps. It is the responsibility of the receiver to group the bits.

 The advantage of synchronous transmission is speed. With no extra bits or gaps to
introduce at the sending end and remove at the receiving end, and, by extension,
with fewer(a small number) bits to move across the link, synchronous transmission
is faster than asynchronous transmission. For this reason, it is more useful for high-
speed applications such as the transmission of data from one computer to another.
Byte synchronization is accomplished in the data link layer. We need to
emphasize(give special importance) one point here. Although there is no gap
between characters in synchronous serial transmission, there may be uneven gaps
between frames

Asynchronous transmission
 In asynchronous transmission data is transmitted one byte at a time. This type of
transmission is most commonly used by microcomputer. The data is transmitted
character-by-character. In asynchronous transmission does not occur at
predetermine or regular interval (i.e not synchronized). A sending device can
transmit bytes at any time and the receiving device must be ready to accept them
as they arrive. A start bit marks the beginning of a byte and a stop bit marks the
end of the byte. An additional bit called a parity bit is sometime included at the
end of each byte to allow for error checking

COMMUNICATION MEDIA
 Communication media are the links that provide paths for communicating devices.
 For example, the transmission medium for two
 people having a dinner conversation is the air. The air can also be used to convey
the
 message in a smoke signal. For a written message, the transmission
 medium might be a mail carrier, a truck, or an airplane.

Guide media
 Guide media are those media which uses cables and wires to transmit data
 This is further divide into
 Coaxial cable
 Twisted pair cable
 Fiber optic

Coaxial Cable
 Coax has a central core conductor of solid or stranded wire (usually copper)
enclosed in an insulating sheath, which is, in turn, encased in an outer conductor of
metal foil, braid, or a combination of the two. The outer metallic wrapping serves
both as a shield against noise and as the second conductor, which completes the
circuit. This outer conductor is also enclosed in an insulating sheath, and the whole
cable is protected by a plastic cover.

Twisted-Pair Cable
Twisted pair cable consists of one or more pairs of copper wires . The pairs are twisted
to provide protection against crosstalk the noise generated by adjacent pairs for
example:
Telephone wire
Two types:
1) Shielded twisted pair
2) Un-Shielded twisted pair

UTP
 Unshielded twisted pair cable is a common networking media . It consists of four
pairs of thin copper wires in color coded plastic insulation that are twisted together
. The wire pair are then covered within a plastic outer jacket

STP
 Shielded twisted pair cable consists four pairs of thin copper wires covered in color
coded plastic insulation that are twisted together . Each pair is wrapped in another
layer of metallic foil this layer is wrapped with a plastic outer jacket

Fiber optic cable
 Fiber optic cables represent the latest technological developments being very fine
cables that can carry several hundred thousands voice communication
simultaneously . It is more frequently used for longer high bandwidth transmission
on LAN and WAN . A single fiber optic is a glass or hard transparent(able to be
seen through) plastic having diameter equal to that of the human hair and it carries
data in the form of pules of light . A signal fiber optic cable may contain thousands
of fibers . The glass or plastic fiber is called a core and it has a cladding . Core is the
light transmitting element

 At the center of the optical fiber and all the light signals travel through the core .
Cladding protects the light traveling through core from leakage outside the cable .
These cables are capable of transmitting the data free of any Electro – Magnetic
Interference (EMI) effects

UNGUIDED COMMUNICATION MEDIA
 Unguided media transport electromagnetic waves without using a physical
conductor.
 This type of communication is often referred to as wireless communication. Signals
 are normally broadcast(to send out) through free space and thus are available to
anyone who has a
 device capable of receiving them.

 The commonly used wireless transmission media.
 Radio waves
 Micro waves
 Infrared waves

 Radio waves:
 Radio wave distribute radio signals through the air over long distances such as
between cities, regions and countries and short distances such as within an office
or home. Radio waves are normally multi-directional. When an antenna transmits
radio waves they are propagated(to spread) in all directions. The multi-directional
characteristics of radio waves make them useful for multicasting in which there is
one sender but many receiver. It has frequency between 10 khz to 1 ghz. Our AM
and FM radio stations, cordless phone and televisions are example of multicasting.

 Microwaves:
Is that type of transmission that takes place through microwaves. Microwaves are
similar to Radio waves and can be used to transmit the data between microwave
stations. These microwaves travels in a straight i.e. line of sight. Due to this reason the
transmission distance between stations is limited to about 30 miles because of the
earth surface's curvature. The microwave stations are usually located at the hilltops or
towers. Electronic waves with frequencies between 1 ghz to 300 ghz are normally
called microwaves.

 For long distance communication
Satellite microwaves technology is used. A communication satellite is a device that
receives microwave signals from an earth-based station, amplifies(to make large) the
signals and broadcasts the signals back over a wide area to any number of earth-
based station. Satellite micro wave transmission is used to transmit signals throughout
the world

Infrared
 Infrared is a short distance wireless transmission medium that sends signals using
infrared light waves. Infrared frequencies are just below visible light. These high
frequencies allow high speed data transmission. This technology is similar to the
use of a remote control for a TV. Infrared transmission can be affected by objects
obstructing (blocking)sender or receiver.
 Infrared is used in device such as the mouse , wireless keyboard and printer. With
infrared computer can transfer files and other digital data bi-directional. Infrared
adapters are installed in many laptops handheld personal devices and mobile
phones.

Communication devices
 Communication devices are used for communication between the computers or
other devices. The following are some important communication devices.
 Switch
 Router
 Gateway

Switch
 A network switch also called switching hub. Bridging hub is computer networking
device that connects devices together on a computer network by using packet
switching to receive process and forward data to the destination device

Router
Is a special computer that direct communicating messages when several networks are
connected together it handles major data traffic
Or
A router is a device that forwards data packets along networks. A router is connected
to at least two networks . Commonly two LANs or WANs or a LAN and its ISPs
network. Router are located at gateways. The places where two or more network
connected.

Gateway
 Is an interface that enables dissimilar networks to communicate such as a LAN with
WAN

 Modems
 A modem, short for modulator/demodulator, is a device that converts the digital
 signals generated by a computer into analog signals that can travel over
 conventional (according to the accepted standareds)phone lines. The modem at
the receiving end converts the signal
 back into a format the computer can understand. Modems can be used as
 a means to connect to an ISP or as a mechanism for dialing up to a LAN.
 Modems can be internal add-in expansion cards, external devices that connect
 to the serial or USB port of a system,

hubs
 Hubs are
 used in networks that use twisted-pair cabling to connect devices. Hubs can
 also be joined together to create larger networks. Hubs are simple devices
 that direct data packets to all devices connected to the hub,
 The difference between hubs and switches is in how the devices deal
 with the data that they receive. Whereas a hub forwards the data it receives
 to all of the ports on the device, If a message1 comes in for computer “A”, that message
is sent out all the other ports, regardless of which one computer “A” is on: a switch
forwards it only to the port that
 connects to the destination device.

 And when computer “A” responds, its response also goes out to every other port
on the hub . Every computer connected to the hub “sees” everything that every
other computer on the hub sees.

Networking architecture
 The different techniques used to establish a network are called network modals or
architecture . These are two types of networks modals
1)Client-Server modal or architecture
2)Peer-to-Peer

Client-Server Modal
 In a client/server arrangement network services are located on a central computer
called server . The server is the central computer that controls the entire network.
The server responds to the request of clients for file print and other services.
Typically desktop computers function as clients and one or more computers with
additional processing power memory and specialized software function as server

 Networks administrator controls the server whereas ordinary users use clients .
Each user has his own rights which are assigned by the administrator window NT,
window 2000, UNIX and LINUX are used for client-server networks

Advantages client/server
 Provide for better security
 Easier to administer when the network is large because the administrator is
centralized
 All data can be backed on one central location

Disadvantages
 Require expensive specialized network administrative and operational software
 Requires expensive more powerful hardware for server machine
 Require a professional administrator
 Has a single point of failure user data is unavailable if the server is down .

Peer-to-Peer Modal
 In a peer-to-peer network , networked computer act as equal partner or peer . As
peer each computer can act as a client or server function . At one time computer. A
may make a request for a file from computer B, which then provides the file to
computer A. In this case Computer A function as client . While B function as the
server . At a later time computer A and B can reverse roles . Operating systems
such as window-95 and window-98 are used for peer-to-peer networks . In this
modal no network administrator is required . As there is no central control, so this
modal is less secure .

Advantages of peer-to-peer
 Less expensive to implement
 Does not required additional specializes networks administration software
 Does not required a dedicated network administrator

Disadvantages peer-to-peer
 Does not scale well to large networks and network become unmanageable
 Each user must be trained to perform administrative tasks
 Less secure
 All machine sharing the resource negatively impact the performance

LAN(local area network)
 Privately owned
 Links devices in single office, building or campus.
 Limited to few kilometres.
 Sharing of resources: Hardware or data.
 Use a single transmission media.
 Topology: Ring, bus, star.

MAN(metropolitan area network)
 Extend over an entire city.
 Owned and operated by a private company
 Service provider
 Public company.

WAN(wide area network)
 Provides long-transmission of data, voice, image and video information over large
geographic areas that may comprise a country, a continent(able to control) or even
the whole world.

 The most well-known WAN is the internet which may cover the entire globe. Most
WANs (like the internet) are not owned by any one organization but rather exist
under collective or distribute ownership and management.

 A Personal Area Network (PAN) is smallest network which is very personal to a user.
This may include Bluetooth enabled devices or infra-red enabled devices. PAN has
connectivity range up to 10 meters. PAN may include wireless computer keyboard
and mouse, Bluetooth enabled headphones, wireless printers, and TV remotes.
Personal Area Network

Virtual private network
 Virtual private network (VPN) is a technology that is gaining popularity among
large organizations that use the global Internet for both intra- and
interorganization communication, but require privacy in their internal
communications.
 A private network is designed for use inside an organization. It allows access to
shared resources and, at the same time, provides privacy. Before we discuss some
aspects of these networks, let us define two commonly used, related terms: intranet
and extranet.
 Intranet An intranet is a private network (LAN) that uses the Internet model.
However, access to the network is limited to the users inside the organization. The
network uses application programs defined for the global Internet, such as HTTP,
and may have Web servers, print servers, file servers, and so on.

 Extranet An extranet is the same as an intranet with one major difference: Some
resources may be accessed by specific groups of users outside the organization
under the control of the network administrator. For example, an organization may
allow authorized customers access to product specifications, availability, and online
ordering. A university or a college can allow distance learning students access to
the computer lab after passwords have been checked
 Addressing A private network that uses the Internet model must use IP addresses.

Physical connection
 Point-to-point:
 Provides a dedicated link between two devices.
 Entire capacity of the link is used.

Multipoint connection
 Also called as multidrop.
 More than two specific devices share [spatially or temporally] a single link.
 Spatially shared: Several devices can use the link simultaneously
 Timeshare: Users must take turns.

Network topologies
 Network topology refers to the physical layout and connectivity of computers in a
network. Network topologies are categorized into the following four basics types :
 Star
 Ring
 Bus
 Mesh

Star topology
 Each device has a dedicated point-to-point link only to a central controller [Hub].
The devices are not directly linked to one another.
 No direct connection or traffic.
 The controller acts as an exchange: If one device wants to send data to another, it
sends the data to the controller, which then relays the data to the other connected
device

 Advantages:
 less expensive,
 one link and one I/O port,
 easy to install and reconfigure,
 less cabling (but more than bus or ring),
 node failure will not affect others,
 fault identification is easier.

 Disadvantages :
 Single point of failure.

 Ring topology:
 In a ring topology each device has a dedicated point-to-point connection with
only the two devices on either side of it. A signal is passed along the ring in one
direction, from device to device, until it reaches its destination. Each device in the
ring incorporates a repeater. When a device receives a signal intended(to plane
do something) for another device, its repeater regenerates the bits and passes
them along

 Advantages:
 Easy to install,
 fault isolation is easier,
 Signal circulates at all times (alarm alerts the problem and its location).

 Disadvantages:
 Unidirectional traffic, (each packet of data must pass through all the computers
between source and destination this make it slower than star topology)
 in a simple ring; break in the ring can disable entire network.

Bus topology
 A bus topology, on the other hand, is multipoint. One long cable acts as a backbone to
link all the devices in a network
 Nodes are connected to the bus cable by drop lines and taps. A drop line is a
connection running between the device and the main cable.
 In case of Bus topology, all devices share single communication line or cable. Bus
topology may have problem while multiple hosts sending data at the same time. It is
one of the simple forms of networking where a failure of a device does not affect the
other devices. But failure of the shared communication line can make all other devices
stop functioning.
 As a signal travels along the backbone, some of its energy is transformed into heat.
Therefore, it becomes weaker and weaker as it travels farther and farther. For this
reason there is a limit on the number of taps a bus can support and on the distance
between those taps.

 Advantages:
 easy to install,
 less cabling.
 Disadvantages :
 Limit on number of taps and the distance between taps,
 difficult to identify fault,
 signal degradation,
 modification is difficult.

Mesh topology
 Every device has a dedicated point-to-point link to every other device.
 Dedicated means that the link carries traffic only between the two devices it
connects.

 Advantages:
 Data can be transmitted from different devices simultaneously. This
topology can withstand high traffic.
 Even if one of the components fails there is always an alternative(one
after the other) link present. So data transfer doesn't affected.
 Expansion (the act of expanding)and modification in topology can be done
without disrupting(to break up) other nodes

 Disadvantages:
 amount of cabling, I/O ports,
 installation is difficult,
 expensive hardware.
 Overall cost of this is too high as compared to other network topologies

Tasks involved in sending a letter
The letter is written put
in an envelop and
dropped in a mail box
The letter is carried
from the mail box to a
post office
The letter is delivered to
carrier by the post office
The letter is delivered
from the carrier by the
post office
The letter is carried
from the post office to a
mail box
The letter is picked up
removed from the
envelop and read
sender
receiver

Sender, Receiver, and Carrier
 At the Sender Site
 Let us first describe, in order, the activities that take place at the sender site.
 Higher layer. The sender writes the letter, inserts the letter in an envelope, writes
the sender and receiver addresses, and drops the letter in a mailbox.
 Middle layer. The letter is picked up by a letter carrier and delivered to the post
office.
 Lower layer. The letter is sorted at the post office; a carrier transports the letter.

 At the Receiver Site
 Lower layer. The carrier transports the letter to the post office.
 Middle layer. The letter is sorted and delivered to the recipient's mailbox.
 Higher layer. The receiver picks up the letter, opens the envelope, and reads it.

Protocols
 In computer networks, communication occurs between entities in different systems.
An entity is anything capable of sending or receiving information. For
communication to occur, the entities must agree on a protocol. A protocol is a set
of rules that govern data communications. A protocol defines what is
communicated, how it is communicated, and when it is communicated. The key
elements of a protocol are syntax, semantics, and timing.

OSI model
 The Open System Interconnection (OSI) model includes a set of protocols that
attempt to define and standardization the data communication process.
 The OSI model is a concept that describes , how data communications should take
place . It divides the process into seven steps called layers.

History of OSI
 The OSI protocols were defined by the International Standard Organization (ISO).
 In the beginning of 1983 OSI model developed by representatives of major
computer and telecommunication companies.
 OSI was officially adopted as an International Standard by ISO.

OSI Architecture
According to OSI document [ISO7498], the purpose
of OSI is as follows:
 – "The purpose of this International Standard Reference Model of Open Systems
Interconnection is to provide a common basis for the coordination of standards
development for the purpose of system interconnection , while allowing existing
standards to be placed into perspective(natural scene) within the overall
Reference Model."

OSI Model
Network Group
Application Group
Transport Group

OSI Model
 Three main groups of OSI model . The OSI model consists of seven layer is further
grouped according to their function into three groups;
 Application Group
 Transport group
 Network group

Application Group
 The application group is consists of the session, presentation and application layer.

Transport Group
 The transport group consists of a single layer,
 the transport layer

Network Group
 The network group is made up of the physical, data-link, and network layer.

OSI Layers
 Physical Layer
 Data-Link Layer
 Network Layer
 Transport Layer
 Session Layer
 Presentation Layer
 Application Layer

An Exchange Using The OSI Model

Physical layer
 This is lowermost layer of the OSI model.
 It is responsible for the actual physical connection between the devices. Such
physical connection may be made by using twisted pair cable.
 It is concerned with transmitting bits over a communication channel.
 This layer consists of simply the wire or media by which the network signals are
conducted.
 Physical layer includes hardware (wire, plugs and sockets etc.).

Physical layer
 In other words, this layer represent the physical aspects of the network such as
cable and connectors.
 The basic functions of this layer are handles voltages, electrical pulses, connectors
and switches so that data can be transmitted from one network device to another.

Data-link layer
 It is responsible for node-to-node delivery of data.
 It receives the data from network layer and creates FRAMES , add physical address
to these frames & pass them to physical layer
It consist of 2 layers:
 Logical Link Layer (LLC) :Defines the methods and provides addressing
information for communication between network devices.
 Medium Access Control (MAC): Establishes and maintains links between
communicating devices.

Data-link layer
 Framing :DLL divides the bits received from N/W layer into frames. (Frame
contains all the addressing information necessary to travel from S to D).
 Physical addressing: After creating frames, DLL adds physical address of
sender/receiver (MAC address) in the header of each frame.
 Flow Control: DLL prevents the fast sender from drowning the slow receiver.

Functions of Data Link Layer
 Error Control: It provides the mechanism of error control in which it detects &
retransmits damaged or lost frames.
 Access Control: MAC layer of DLL provides help to determine which device has
control over the channel.

Network Layer
 It is the third layer of OSI model.
 This layer establishes the route between the sending and receiving stations.
 It handles the routing of data (sending in the right direction to the right destination
on outgoing transmissions and receiving incoming transmission at the packet). The
layer does routing & forwarding of data.
 If two systems are attached to different networks with devices like routers, then
N/W layer is used.
 Thus DLL overseas the delivery of the packet between the two systems on same
network and the network layer ensures that the packet gets its point of origin to its
final destination.
 In this layer use the Internet protocol (IP).

Functions of Network Layer
 Internetworking: It provides Internetworking.
 Logical Addressing: When packet is sent outside the network, N/W layer adds
Logical (network) address of the sender & receiver to each packet. Network
addresses are assigned to local devices by n/w administrator and assigned
dynamically by special server called DHCP (Dynamic Host Configuration Protocol)
 Routing : When independent n/w are connected to create internetwork several
routes are available to send the data from S to D. These n/w are interconnected by
routers & gateways that route the packet to final destination.

Transport layer
 It is forth layer of OSI model. It is responsible for constructing stream of data
packets, sending and checking for correct delivery.
 This layer manages the end to end control (for example determining whether all
packets have arrived) and error checking.
 The transport layer ensures data is successfully sent and received between two
nodes.
 If data is sent incorrectly, this layer has the responsibility to ask for retransmission
of the data.

Transport layer
 Specially it provides a reliable network independent message interchange service
to the application group.
 This layer acts as an interface between the bottom and top three layers.
 In this layer use of TCP & UDP (User Datagram Protocol.

Transport layer
 Transport Layer provides two types of services:
 Connection Oriented Transmission: In this type of transmission the receiving
devices sends an acknowledge back to the source after a packet or group of packet
is received. It is slower transmission method.
 Connectionless Transmission: In this type of transmission the receiving devices
does not sends an acknowledge back to the source. It is faster transmission
method.

Functions of Transport Layer
 Segmentation of message into packet & reassembly of packets into message.
 Port addressing: Computers run several processes. TL header include a port
address with each process.
 Flow Control: Flow control facility prevents the source form sending data packets
faster than the destination can handle.
 Error control: TL ensures that the entire message arrives at the receiving TL
without error.

Session Layer
 Session layer is the fifth layer of OSI Model
 It has the responsibility of beginning, maintaining and ending the communication
between two devices, called session.
 It also provides for orderly communication between devices by regulating(correct)
the flow of data.

Functions of Session Layer
 Establishing, Maintaining and ending a session:
When sending device first contact with receiving device, it sends
syn(synchronization(to happen at the same time)) packet to establish a connection &
determines the order in which information will be sent. Receiver sends ack
(acknowledgement). So the session can be set & end.
 Dialog Control: This function determines that which device will communicate first
and the amount of data that will be sent.
 Dialog separation: Process of adding checkpoints & markers to the stream of data
is called dialog separation.

Presentation Layer
 This is the sixth or second last layer of OSI model. This layer defines how the
system provides files and services in a uniform way to application.
 It was designed for data encryption, decryption and compression.
 This layer can in some ways be considered the function of the operating system.

Functions of Presentation Layer
 Data Presentation or Translation: Because different computers use different
encoding systems. It ensures that the data being sent is in the format that the
recipient can process.
 Data Encryption: PL provides this facility by which hides the information from
everyone except the person who originally sent the information & the intended
recipient. When encrypted data arrives at destination, PL decrypts the message.
 Data Compression: PL shrinks large amount of data into smaller pieces i.e. it
reduces the size of data.

Application Layer
 It is the topmost i.e. seventh layer of OSI Model.
 It enables the user to access the network.
 It provides user interface & supports for services such as e-mail, file transfer, access
to the world wide web.
 So it provides services to different user applications.

Functions of Application Layer
 Mail Services: This application provides various e-mail services.
 File transfer & Access: It allows users to access files in a remote host, to retrieve
files from remote computer for use etc.
 Remote log-in: A user can log into a remote computer and access the resources of
that computer.
 Accessing the World Wide Web: Most common application today is the access of
the World Wide Web.

TCP/IP
 Communication between computers on a network is done through protocol suits(a
number of things forming a set). The most widely used and most widely available
protocol suite is TCP/IP protocol suite. TCP/IP is an industry standard suite of
protocols designed for local and wide area network. It was developed by the united
states. Department of defense (DOD) advanced research projects agency (ARPA) in
1969 for a research sharing project called ARPANET. Internet was built on the
foundation of the original ARPANET projects

TCP/IP protocol suite architecture
 TCP/IP architecture
 TCP/IP PORTS
 TCP/IP Application

TCP/IP Architecture
 TCP/IP protocol suit consists of a layered architecture where each layer depicts
some functionality which can be carried out by a protocol. Each layer usually has
more than one protocol options to carry out the responsibility that the layer
adhere. It is named from two of the most important protocols in it. That is
Transmission Control Protocol and Internet Protocol, TCP/IP is normally considered
to be a 4 layer system. The TCP/IP model breaks down into the following four layer
 Application layer
 Transport layer
 Internet layer
 Network Access Layer

TCP/IP Architecture
 All application data whether it is an email a file an instant message a video or voice
call is divided into data segments and encapsulated in transport layer PDU,s (TCP
or UDP segments). The transport layer PDU,s (protocol data unit) are then
encapsulated in internet layer's internet protocol packets.
 The internet protocol packets are then divided into frames at the Network Access
Layer and transmitted across the physical media (copper wire, fiber optic cable or
the air) to the next station in the network .

Application Layer
 This is top layer of TCP/IP protocol suite. This layer includes applications or
processes that use transport layer protocols to deliver the destination computers.

Transport Layer
 The transport layer provide the means for the transport data segments across the
internet. The transport layer is concerned with host-to-host communication.
Transmission Control Protocol provides reliable connection-oriented transport of
data between two endpoints (sockets) on two computers that use Internet Protocol
to communicate.

Internet Layer
 The internet layer provides a global logical addressing scheme(a plan or
arrangement or a way of doing) a process for packetization of data. Another
process for routing packets to their destination and for providing connectivity
between networks. The internet layer is concerned with network to network
communication. The main protocol used at this layer is IP

Network Access Layer
 The network access layer provides access to the physical network. The data is
transmitted and received across the physical network in network access layer. This
layer combines the physical and Data link layers and routes the data between
devices on the same network. It also manages the exchange of data between the
network and other devices.

Port SOME IMPORTANT POINTS
 Port is a communication channel through which device can communicate with each
other.
 For example :
 Keyboard port , mouse port
 Two types of port :
 Physical port :
like that type of port that we can watch it physically like mother board
port e.g usb port , serial port , VGA port

 Logical port :
 with the help of logical port we do protocol communication with each other ,
network application communication with each other.
 E.g. telnet data send from the computer to another computer so that data go in
telnet form so the other computer received it in telnet form and open it in telnet
form.
 Internet explore send received and show in internet explore form
 Mozilla Firefox send received and show in Mozilla Firefox form
 HTTP send received and show in HTTP form

telnet some Important points
 telnet provide command line remote administration of a device.
 Or
 To access device remotely or to do changed in it device form remote location
 Devices router , switch , firewall , computer ;
 Basically telnet is a protocol which used port no 23
 telnet is not secure because telnet communication is not in encrypted form.

TCP/IP Port
 Every computer or device on the internet must have a unique number assigned to it called the IP
address. This IP address is used to recognize each particular computer out of the millions of other
computers connected to the internet. The information sent over the internet to a particular computer is
received by using TCP or UDP ports. There are a total of 65,535 TCP ports and another 65,535 UDP
ports. The internet assigned numbers authority (IANA) is responsible for assigning TCP and UDP port
numbers to specific uses.
 For instance port 23 is used for telnet services, HTTP uses port 80 for providing web browsing services
and FTP servers use TCP ports 20 and 21 to send and receive information. There are some ports that
are assigned, some reserved and many unassigned which may be utilized by application programs.
 The port numbers are divided into three ranges:
 The well known ports
 The registered ports
 The dynamic and / or private port

Well known port number
 Well-known ports (0-1023) are used for the major internet application such as web
and email. For example all port 80 packets (HTTP packets) are directed to and
processed by a web server

Registered Port Number
 Registered ports are assigned to application that are mostly vendor specific. Such
as skype and Bit torrent. The registered ports are in the range 1024 -49151

Dynamic Port number
 The dynamic and /or private Ports are those in the range 49152-65535. these ports
are not used by any defined application

Dynamic port number
 The dynamic port numbers (also known as the private port numbers) are
the port numbers that are available for use by any application to use in
communicating with any other application, using the Internet's Transmission
Control Protocol (TCP) or the User Datagram Protocol (UDP).

TCP/IP Application
 All modern operating system supports TCP/IP and most large private networks rely
on TCP/IP for much of their traffic. A technology used for connecting dissimilar
systems. Many TCP/IP application protocols were designed to access and transfer
data between dissimilar systems. These protocols include HTTP, FTP and Telnet,
TCP/IP provides a robust, scalable cross-platform client/server framework.

 The TCP/IP is used by the following application
 Web browsers (internet Explorer, FireFox,Safari,Opera etc)
 Web servers
 File servers
 Terminal servers
 Online games
 File transfer application
 Microsoft window update
 Anti-virus application

Packet switching
 The entire message is broken down into smaller chunks called packets. The
switching information is added in the header of each packet and transmitted
independently.

Packet switching
 Packet switching enhances (better) line efficiency as packets from multiple
applications can be multiplexed over the carrier. The internet uses packet switching
technique. Packet switching enables the user to differentiate data streams based on
priorities. Packets are stored and forwarded according to their priority to provide
quality of service.

 Example of packet-switching: In the second example, you switch on your PC and
connect to your favorite site that offers a number of applications you can
download from, so you begin downloading one application at a time. Each
has to find its own route to the destination, i.e., your computer. Each packet finds
its way using the information it carries, such as the source and destination IP
address. If network congestion occurs, the routers responsible for routing packets
between networks will automatically select different paths to ensure data is
transferred as required. This is an example of a packet-switched network

Circuit switching
 Circuit switching is a scheme in which the network sets up a dedicated point-to-
point connection between nodes and terminals before the communication starts
just like the nodes were already connected.
 or
 When two nodes communicate with each other over a dedicated communication
path, it is called circuit switching. There is a need of pre-specified route from which
data travels and no other data is permitted(to allow). In circuit switching to transfer
the data, circuit must be established so that the data transfer can take place.
 Circuits can be permanent or temporary. Applications which use circuit switching
may have to go through three phases:
 Establish a circuit
 Transfer the data
 Disconnect the circuit

Circuit switching
 Circuit switching was designed for voice applications. Telephone is the best suitable
example of circuit switching. Before a user can make a call, a virtual path between
caller and callee is established over the network.

IP addressing
 An internet protocol address (IP address) is number that is used to identify a
device. For example a computer a printer etc. on the network. Each device on a
network must have a unique IP address to communicate with other network
devices. A host (usually a computer) is a device that sends or receives information
on the network. Network devices transmit the data across the network. These
devices include hubs switches and routers. On a LAN each host and network device
must have an IP address within the same network to be able to communicate with
each other.
 An IP address can be static or dynamic. A static IP address will never change and its
permanent internet address. A dynamic IP address is a temporary address that is
assigned each time a computer or device access the internet.

IP addressing
 The address is made up of 32 binary bits which can be divided into a network
portion and host portion with the help of a subnet mask. The 32 binary bits are
broken into four octets(1 octet = 8bits). Each octet is represented in decimal and
separated by a period (dot). For this reasons an IP address is expressed in dotted
decimal format (eg, 172.16.81.100). The value in each octet range from 0 to 255 in
decimal or 00000000-11111111 in binary.
 The following IP address is an example which shows an IP address represented in
both binary and decimal formats.
 00001010.00000001.00010111.00010011 (binary)10 231 19 decimal

Classes of IP address
 There are five different classes of an IP address from A to E
 Class A
 Class B
 Class c
 Class D
 Class E

Class A
 Class A is used for the large networks and is implemented by large companies with
many network devices. Binary address for the class A start with 0. its range is
between 1 to 126 and the default subnet mask of this class is 255.0.0.0. its network
part consists of 1 octet and host part consists of 3 octets. An example of class A is
100.10.11.1
+---------------------+---------------+---------------+--------------------+
| network part | Host Part |
+---------------------+---------------+----------------+-------------------+
0 7-8 15-16 23-24 31
1 octets 3 octets

Class B
 Class B address scheme is used for the medium sized networks. The binary address
for the class B starts with 10. the range of the IP address in the class B is between
128 to 191 and the default subnet mask of this class B is 255.255.0.0 . Its network
part consists of 2 octets and Host part also consists of 2 octets. An example of the
class B address is 150.101.110.120.
+---------------------+---------------+---------------+--------------------+
+---------------------+---------------+----------------+-------------------+
0 7-8 15-16 23-24 31
2 octets 3 octets

Class C
 Class C is used for the small networks. The binary address for the class C starts with
110. the range addresses in the class C is between 192 to 223 and the default
subnet mask for this class is 255.255.255.0 it network part consists of 3 octets and
Host part consists of 1 octet. An example of the class C IP address is
210.190.100.150
+---------------------+---------------+---------------+--------------------+
+---------------------+---------------+----------------+-------------------+
0 7-8 15-16 23-24 31
3 octets 1 octets

Class D
 Class D is for special use for multicasting. The binary addresses for the class D
starts with 1110 and the IP address ranges from 224 to 239. An example of the
class D IP address is 230.150.110.11

Class E
 Class E is under experimental research. The binary address can start with 1111 and
the decimal can be in range from 240 to 255. An example of the class E IP address
is 245.101.110.110

Subnet Masks
 A subnetwork or subnet is a logical subdivision of an IP network.[1] The practice of
dividing a network into two or more networks is called subnetting
 Subnet mask indicates the network portion of an IP address. Like the IP address the
subnet mask is a dotted-decimal number. Usually all hosts within a LAN use the
same subnet mask. Subnet mask is a 32 bit combination used to describe which
portion of an address refers to the subnet and which part refer to the host.
 Figure shows default subnet masks for usable IP address that are mapped to the
first three classes of IP adresses

 Class A(1-126):
Default subnet mask = 255.0.0.0
Network HostHostHost
255 0 0 0

 Class B (128-191)
Network HostHostNetwork
255 255 0 0

 Class C (192-223)
Network HostNetworkNetwork
255 255 255 0

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