The network topologies
Network topology is the overall scenerio of network
and arrangement in which nodes on a network are
connected to each other. It defines in two types:
LAN (local area network)
WAN(wide area network)
LAN’s (LocAL AreA Networks)
Set of hosts in same building connected
by a high speed medium such as
Eg . Network setup in a building
A LAN might be a single IP network or a
collection of networks or subnets that
are connected through high speed
switches and routers.
wAN’s (wide AreA Networks)
WAN is a network that covers a
potentially vast geographical area.
Eg . Internet
A WAN makes use of third party service
providers for interconnection such as
A network protocol is the part of network that
we configure but can’t see.
It controlls data transmission b/w systems
across the network.
These are abstract common structure used
to describe communication b/w systems.
The two network models are :
1. ISO/OSI model ( International
Standards Organisation/Open Systems
2. TCP/IP model (Transmission Controll
1. ISO/OSI model
Application : Utilities such as TELNET and FTP opertate at this layer.
Presentation : It allows incompatible in the application layer to communicate via
layer the session layer.
layer It handles security and creation of the sessions.
TCP operates at this layer
Network Manages the delivery of data via the data link layer and is used
layer by the transport layer.
layer It performs error checking and retransmit frames that are
not received correctly
Describes the network Hardware
2. TCP/IP Model
Fig :2-The five
layers of the
Transport Transport model
Data link Network interface
Layer 1: Physical:
Layer1 deals with the network
Itcorresponds to the physical
layer in the OSI model.
Layer 2: Network Interface.
Thislayer specifies how to
organize data into packets called
frames and how to address the
machines in a LAN.
Itcorresponds to the data link
layer in the OSI model.
Layer 3: Internet.
Thislayer specifies the format of
data packets called IP datagrams
and is responsible for delivering
these datagrams across the
layer corresponds to the
network layer in the OSI model.
Layer 4: Transport.
This layer has protocols that specify
Itcorresponds to the transport layer
in the OSI model.
Layer 5: Application.
Thislayer corresponds to layers 6
and 7 in the OSI model that are
presentation layer and application
Encapsulation & decapsulation
A header is added to each segment that
is received on the way down the layers
is k/as ENCAPSULATION.
A header is removed from each segment
that is received on the way up through
the layers is k/as DECAPSULATION.
It defines the physical components a
machine uses to access the network
and the speed at which network runs.
An Ethernet network has three main
components: data packets, media, and
media access (MAC) mechanism.
Ethernet uses a protocol called
CSMA/CD, which stands for Carrier
Sense Multiple Access with collision
The computer hardware that allows you to
connect a computer to a network is k/as
network interface card.
On an Ethernet network, a hardware
address is burned into a NIC, but the IP
address is not. That means if you change
the NIC of your computer, the hardware
address of your machine changes.
HUBS AND SWITCHES :
Each computer is connected to a different
port on the hub. A hub receives signal on
one port and repeats it on all other ports.
As opposed to a hub, a switch repeats a
received signal only on a port to which the
intended recipient of the data is connected.
When a switch is powered up, it starts off
acting like a hub.
A router is a machine that forwards
packets from one network to another.
A hub connects computers and a router
IP (version 4) addresses are 32-bit
Each IP address has a structure—that is,
it’s composed of two parts, netid and
hostid. All the computers on the same
network (e.g.,LAN) have the same netid
but different hostids.
Netid is assigned by RIR’s and hostid is
assigned by local network administrator.
IP addresses are assigned by special
organisations k/as Regional internet
Class A addresses
Class A network number falls in the
range of 0 to 127.
Mayuresh kumar bhardwaj
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