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RUSTAMJI INSTITUTE OF
TECHNOLOGY
Submitted by:Anup Pandey
Contents :
Computer Network
Transmission Modes
Types of Network
Protocols
Models (OSI and TCP/IP)
Comparison between models
Network 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.
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.
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
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.
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
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.
OSI Model
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
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
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
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
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.
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.
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.
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
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
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
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
MESH Topology
All computers connected together
Internet is a mesh network
Advantage
Data will always be delivered
Disadvantages
Lots of cable
Hard to setup
TREE Topology
Hierarchal Model
Advantages
Scaleable
Easy Implementation
Easy Troubleshooting
Thank You