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RUSTAMJI INSTITUTE OF TECHNOLOGY Submitted by: Anup Pandey

Computer network : models and topologies

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Page 1: Computer network : models and topologies

RUSTAMJI INSTITUTE OF

TECHNOLOGY

Submitted by:Anup Pandey

Page 2: Computer network : models and topologies

Contents :

Computer Network

Transmission Modes

Types of Network

Protocols

Models (OSI and TCP/IP)

Comparison between models

Network Topologies

Page 3: Computer network : models and topologies

Computer Network

Computer network

is a number of computers (also

Known as Nodes) connected by some communication lines.

Uses of Computer Network: Exchange of information between them

Interconnected small computers in place of large computers

For direct communication e g: voice , video.

Page 4: Computer network : models and topologies

Modes of Communication Point to point

Broadcasting

Multicasting

it is between the point to point and broadcasting

Dedicated (Simplex, half duplex, full duplex).

Shared (Multiplexing).

Dedicated (Channel level- one way)

Shared (Multiple access)

shared between multiple access and some

protocols are used that how they are using.

Communication to the specified group but not to others.

Page 5: Computer network : models and topologies

Transmission Modes

Simplex One direction

○ e.g. Television

Half duplex Either direction, but only one way

at a time○ e.g. police radio

Full duplex Both directions at the same time

○ e.g. telephone

Page 6: Computer network : models and topologies

Types of Networks

LAN (Local Area Network)

MAN (Metropolitan Area Network)

Privately Owned (Main feature)

Contains printers, servers and computers

Systems are close to each other

Limited to a building

For bigger sizes (City, State etc.)

Access issues : How to connect each one of them

because each of them are geographically distributed.

A network provider sells time.

Page 7: Computer network : models and topologies

WAN (Wide Area Network)

Costly

For more then 1000 of Km.

Networks of Networks (LAN +LAN +…)

Typically use public or leased lines

The Internet is a WAN

Page 8: Computer network : models and topologies

Protocols :

These are the rules and regulations that how

communication takes place.

These are the building blocks of a Network.

Each protocol object has two interfaces.1. Service Interface: Defines operation on this Protocols

2. Peer to Peer interface: Defines messages exchanged with peer.

Page 9: Computer network : models and topologies

OSI Model

Page 10: Computer network : models and topologies

Working of each layers of OSI Model

Physical Layer : How to Transmit Bits

Data Link Layer : How to Transmit Frames

Responsible for transmission of bits

Always implemented through hardware

Encompasses mechanical, electrical, and

functional interfaces

Error Detection

Responsible for error-free, reliable transmission of data,

Error correction, Access control.

Line Discipline

• ENQ / ACK (for Peer to Peer)

• POLL / SELECT( for establishment of proper communication

in primary and secondary device)

Flow Control

• STOP & WAIT

• SLIDING WINDOW

Page 11: Computer network : models and topologies

Network Layer : How to route packets to the node

Transport Layer : How to send packets to the

application

Responsible for routing of messages through network

Concerned with type of switching used (circuit v.

packet)

Handles routing between networks, as well as through

packet-switching networks

Concerned with reliable transfer of information

between applications

Includes aspects like flow control and error

checking

Breaks down message size

Isolates messages from lower and upper layers

Page 12: Computer network : models and topologies

Session Layer : Manage connections

Presentation Layer : Encode/ Decode

message security

Application Layer :

Establishes logical connections between systems

Terminates connection at end of session

Manages log-ons, password exchange, log-offs

Provides format and code conversion services

Provides access to network for end-user

User’s capabilities are determined by what

items are available on this layer

Page 13: Computer network : models and topologies

TCP/IP (Transfer Control Protocol)

OSI Model TCP/IP Hierarchy Protocols

7th

Application Layer

6th

Presentation Layer

5th

Session Layer

4th

Transport Layer

3rd

Network Layer

2nd

Link Layer

1st

Physical Layer

Application Layer

Transport Layer

Network Layer

DataLink Layer

Page 14: Computer network : models and topologies

Application Layer :

The application layer is equivalent to the combined OSI

Session, Presentation and Application Layers.

All the functions Handled by these 3 layers in OSI

model are handled by the Application layer of TCP/IP

model.

This Layer contains all the higher Layer Protocols.

• FTP (File Transfer Protocol)- Basic file transfer between

Hosts ( computers)

• SMTP ( Simple Mail Transfer Protocol)-Used for Email.

• HTTP (Hyper text Transfer Protocol)- For web Browsing

Data unit created at this layer is called Message.

Page 15: Computer network : models and topologies

Transport Layer : This Layer is represented by 2 protocols TCP and UDP

1. TCP ( Transmission Control Protocol)

• TCP is reliable connection Oriented Protocol

• Allows Error Free Transmission

• At the receiving end TCP reassembles the message to

an output stream

• TCP also Handles Flow control.

2. UDP (User Datagram Protocol)

Datagram: A self contained message unit which

contains sufficient information to allow it to be routed from

the source to the destination

• UDP is simpler but used when Reliability and security

are less important the size and speed such as speech,

video.

Page 16: Computer network : models and topologies

Network Layer :

Also referred to as network Layer or internetwork Layer

No error Checking

Datagrams are discarded due to time Out Layers.

Comparison of OSI and TCP/IP models

OSI model has 7 Layers while the TCP/IP has 5 Layers.

Both have Network , Transport and application Layers

but the other Layers are different.

OSI model supports both Connectionless and

Connection Oriented Communication.

TCP/IP supports only Connectionless communication.

Page 17: Computer network : models and topologies

Network Topology

Logical layout of wires and equipment.

Choice affects

Types of Topologies:

• BUS topology

• STAR topology

• RING topology

• MESH topology

• TREE topology

• Network performance

• Network size

• Network collision detection

Page 18: Computer network : models and topologies

BUS Topology

Also called linear bus

One wire connects all nodes

Terminator ends the wires

Advantages

Easy to setup

Small amount of wire

Disadvantages

Slow

Easy to crash

Page 19: Computer network : models and topologies

STAR Topology

All nodes connect to a hub

Packets sent to hub

Hub sends packet to destination

Advantages

Easy to setup

One cable can not crash network

Disadvantages

One hub crashing downs entire network

Uses lots of cable

Most common topology

Page 20: Computer network : models and topologies

RING Topology

Nodes connected in a circle

Tokens used to transmit data

Nodes must wait for token to send

Advantages

Time to send data is known

No data collisions

Disadvantages

Slow

Lots of cable

Page 21: Computer network : models and topologies

MESH Topology

All computers connected together

Internet is a mesh network

Advantage

Data will always be delivered

Disadvantages

Lots of cable

Hard to setup

Page 22: Computer network : models and topologies

TREE Topology

Hierarchal Model

Advantages

Scaleable

Easy Implementation

Easy Troubleshooting

Page 23: Computer network : models and topologies

Thank You