Protocol Suite

7/29/2019 Protocol Suite

1/20

The OSI Model & the TCP/IP Protocol Suite


2/20

Protocols

It means-a set of rules

It is defined as a set of rules that governscommunication.

Eg: Telephonic conversation there are set of rulesthat we need to follow

Dialing the numberPicking up the receiver

Hanging up

In computer networks, communication occursbetween entities. An entity is anything capable ofsending and receiving information.


3/20

Key elements of a protocol are

1 Syntax

Refers to the structure or format of thedata,meaning the order in which they arepresented.

eg- a protocol expect 8 bits to be the address of the

sender,next 8 bits to be the address of the receiverand the rest will be the msg.

2 Semantics

Refers to the meaning of each section of bits.how is a

particular pattern to be interpreted,what action isto be taken based on that interpretation.

Eg-does an address identify the route to be taken to

the final destination


4/20

3 Timings

Refers two characteristics:what data should be sentand how fast it can be sent.

eg-if a sender produces data at 100 megabits persecond but the receiver can process data at only 1mbps,the transmission will overload the receiver

and data will be lost.


5/20

Standards

These are essential in creating and maintaining anopen and competitive market for equipmentmanufactures.

also in guaranteeing national & internationalinteroperability of data and telecommunications

technology and processes.Standards Organisations

1 ISO-International Standard Organization(alsoreffered as International Organization for

Standardization).It is a multinational body dedicated to worldwide

agreement on international standards.


6/20

2 ANSI

American National Standards Institute is acompletely private, non profit corporation,

It aims include serving as the national coordinatinginstitution for United States

3 IEEE

Institute of Electrical and Electronics Engineeringis a professional engineering society in the world.

Aims to advance theory, product quality in the fieldof electrical & electronics engineering.


7/20

Protocol Layer

A protocol is required when two entities need tocommunicate.

when communication is not simple we divide thetask into several layers.

Each layer has to deal with the protocol


8/20

OSI(Open System Interconnection) Model -

ISO is a multinational body dedicated to worldwide

agreement on international standards.It covers all aspects of network communication

which is known as OSI Model.

The purpose is to show how to facilitate

communication b/w different systems.It is a model for understanding and designing a

n/w architecture that is flexible, robust.


9/20

Layers are-

DATA LINK LAYER

NETWORK LAYER

TRANSPORT LAYER

SESSION LAYER

PRESENTATIONLAYER

PHYSICAL LAYER

APPLICATIONLAYER


10/20


11/20

1 Physical Layer

Function is to carry a bit stream over a physicalmedium.

It deals with the mechanical and electricalspecifications of the interface and transmissionmedia.

Functions are : Physical characteristics of interfaces and media.

Representation of bits

Data rate

Physical topology(how the devices are connectedto make connections)

Transmission mode


12/20

2 Data link layerIt makes the physical layer appear error-free to the

upper layer

Functions are:Framing-it divides the stream of bits received from

the n/w layer into manageable data units calledframes.

Physical addressing-adds a header to the frame todefine the sender or receiverFlow control- overwhelming(mouth-

watering/irresistibile)

Error control-add mechanism to detect andretransmit damaged or lost frames, recognizeduplicate framesAccess control


13/20

3 Network layer

It is responsible for the source to destination deliveryof a packet, across multiple n/w.

It ensures that each packet gets from its origin to itsfinal destination.

Functions are

Logical addressing-this layer adds a header to thepacket coming from the upper layer that includesthe logical addresses of the sender and receiver.

Routing-when independent networks are connected

together to create internetworks, the connectingdevices route or switch the packets to their finaldestination.


14/20

4 Transport Layer

It is responsible for process to process delivery of the

msg.other functions are:Service-point addressing(port address)

Segmentation and assembly-msg is divided intotransmittable segments containing a sequence

number. these numbers enables to reassemble andreach the destination and identify and replace thelost packets

Connection control

Flow control

Error control


15/20

5 Session Layer

It is the n/w dialog controller. It establishes,

maintains and synchronizes the interaction b/wcommunicating systems.

Functions are:

Dialog control-it allows two systems to enter into a

dialog.it allows the communication to take place inhalf full duplex mode.

Synchronization-it allows a process to addcheckpoints


16/20

6 Presentation Layer

Translation-the information is changed to bitstreams before it is transmitted.

Encryption-it means the sender transform theoriginal information to another form and sends theresulting msg over the n/w.

Compression-data compression reduces thenumber of bits contained in the information. theyare useful in text, audio, video.


17/20

7 Application Layer

N/w virtual terminal

File transfer, access and management

E-mail services

Directory Service


18/20

TCP/IP PROTOCOL SUITE

APPLICATION

SESSION

TRANSPORT

PRESENTATION

NETWORK

DATA-LINK

NETWORK

PHYSICAL

APPLICATION

DATA LINK

TRANSPORT

PHYSICAL


19/20

NETWORK

APPLICATION

DATA LINK

TRANSPORT

PHYSICAL

Message

Segment

Datagram

Frame

Bit Stream

APPLICATIONSPECIFIC

ADDRESSES

PORT ADDRESSES

LOGICALADDRESSES

PHYSICALADDRESSES

DATA UNITADDRESSES


20/20

More on Addresses

While routing data packets hop from one nodeto another, during this process the headerinformation i.e. senders address & receiversaddress changes according to address of nextnode.

This means physical address of sender &receiver changes from hop to hop(sendingaddress will be replaced by that of sendingrouter & receiving address will be replaced byphysical address of next node) while logicaladdress of sender & receiver remains the samethroughout the routing process.

Protocol Suite

Documents

Transcript of Protocol Suite