UNIT-01
Network :- Network is a group of nodes connected to
each other using a communication medium. The Medium can be wired or wireless.A node is a devices which is capable to
send or receive the information over the network.
Benefits
of networking :-
—There
are lots of advantages from build up a network, but the three big facts are:
1.File
Sharing.
2.Resource
Sharing.
3.Program
Sharing.
File
Sharing :-From sharing files you can view, modify,and copy files stored on a different computer on the network just as easily as
if they were stored on your computer.
Resource
Sharing :-—Resources such as printers, fax machines,
Storage Devices (HDD, FDD and CD Drives), Webcam,Scanners, Modem and many more
devices can be share.
Program
Sharing :-—Just as you can share files on a network,
you can often also share program on a network. For example,if you have the
right type of software license, you can have a shared copy of Microsoft Office,
or some other program, and keep it on the network server, from where it is also
run.
Types
of Networks :-
—There are different types of network on
basis of geographical area and technology, some of them are:-
1.Local
Area
Networks
(LAN).
2.Metropolitan
Area Networks
(MAN).
3.Wide
Area Networks
(WAN).
4.Storage
Area Networks
(SAN).
5.Intranet.
6.Extranet.
7.VPN.
Local
Area Networks (LAN) :-—Local area networks (LANs) are
used to connect networking devices that are in a very close geographic area,
such as a computer
lab, a
building itself, or a campus environment.
Metropolitan Area Networks (MAN) :-—A large computer network which extends to
a city or to a large university campus is termed as metropolitan area network
or MAN.
—The purpose
of MAN is to
provide the link to the internet in the long run.
Wide
Area Networks (WAN) :-A WAN spans a large geographic area, such
as a state, country.
WANs often connect multiple smaller networks, such as local area networks
(LANs) or metro area networks (MANs).
—The world's most popular WAN is the Internet.
Many WANs
are corporate or research networks that utilize leased lines.
—WANs generally utilize different and much
more expensive networking equipment than do
LANs. Key technologies often found
in WANs include
SONET,
Frame Relay, and ATM.
Storage
Area Networks (SAN) :-Storage area networks (SANs)
provide a high-speed infrastructure to move data between storage devices and
file servers.
Intranet :-An intranet is
basically a network that is local to a company. In other words, users from within this company can find all of their resources without having to go
outside of the company. An intranet can include LANs, private WANs and MANs.
Extranet :-An extranet is
an extended intranet, where certain internal services are made available to known external users or external business partners at remote locations.
VPN :-A virtual private network (VPN) is
a special type of secured network. A VPN is used to provide a secure connection
across a public network, such as an internet. Extranets typically use a VPN to
provide a secure connection between a company and its known external users or
offices.
UNIT-02
OSI
(OPEN SYSTEM INTERFACE)MODEL :-It is
a model for understanding data communication between two or more networking devices. It divides the communication process into seven separate layers. Each
layer perform specific functions. There are following seven layers of OSI
model.
Layer-7 Application Layer :-}The
application layer
allow a user to access the information over the network using an application,
and provides an interface for the end user to
operate a
device connected to a network.
}Application
layer functions:-
◦Network
virtual terminal.
◦File
Transfers Access and Management (FTAM).
◦Ability
to print on a network.
◦Electronic
mail.
◦Browsing
the World Wide Web.
◦Directory
Service.
}Network
virtual terminal:- It
is a software version of physical terminal. Using this software user can logon
them network.
}File
Transfers Access and Management (FTAM):- Using the application, user can access
files on a remote host. It also enable the user to retrieve and manage file
from a remote computer so that file can be used on a local computer.
}Ability
to print on a network:-Using
this service user can print their documents on a printer connected in the
network or on a pc of network.
Layer-6 Presentation Layer :-The presentation
layer, is responsible for how an application formats the data to be sent out onto the network. The
presentation layer basically allows an application to read (or understand) the
message.
}Presentation
Layer functions:
◦Translation.
◦Encryption.
◦Compression.
}Translation:- Before Transmitting the information
should be converted into bits format. Presentation layer handle
interoperability between different encoding system used by the computer system.
At the sending device, information is converted into a common format that can
be accepted by all devices. At the receiving side the common format converted
into receiver dependent format.
}ENCRYPTION:- The presentation layer also adds security
to data by encrypting it.Encryption
is a process in which the data is converted into a form that prevents
unauthorized users from reading. Encryption allows a system to carry sensitive
and private information. The encrypted data is decrypted by the presentation
layer at the receiving end. Decryption is a process opposite to encryption, it
converts encrypted message back to its original form.
}COMPRESSION:-Data
compression refers to a process of encoding data using less number of bits.
This process reduces the number of bits used to represent the information. It
is important while transmitting multimedia information, Such as text, Audio and
Video. Lossless and lossy compression are the two types of data compression techniques. In lossless
compression, the data received after decompressing the compressed data is the
exact replica of the original data.
}In lossy
compression, the data received after decompressing the compressed data is not the exact replica of the original data is lost in the compression and
decompression process. Presentation layer is responsible for performing data
compression.
Layer-5 Session Layer :-}The session
layer, provides various services, including tracking the number of bytes that
each end of the session
has acknowledged receiving from the other end of the session.
This session layer allows applications functioning on devices to establish,
manage, and terminate a dialog through the
network.
}Session
layer functions:-
◦Dialog
Control.
◦Synchronization.
}Dialog
control:-It
allow two devices to enter into a dialog (communication process). These dialog
can take place in any communication mode. There are three modes of
communication simplex, half duplex & full duplex.
}Synchronization:- At this layer check points are added into
a stream of data to synchronize the data flow.
Layer-4 Transport Layer :-}The transport
layer of the OSI model, offers end-to-end
communication between end devices through a
network. Depending on the application, the
transport layer either offers connection-oriented
or connectionless communications.
}Transport
layer functions:-
◦Service
Point Addressing
◦Segmentation
and reassembly
◦Connection
control
◦Flow
Control
◦Error
control
◦Identifying
Service.
}Service
Point Addressing:- There
may be many number of programs running at the same time on a computer, for this purpose source-to-destination delivery should also include process-to-process
delivery. For this purpose transport layer uses a port number to identify the
particular process.
}Segmentation
and reassembly:-At
this layer a message is divided into segments, with each segment having a
sequence number. Sequence number helps to reassemble the segments into
transport layer to determine and replace the segment that were lost in the
transmission.
}Connection
Control:- Transport layer provides either
connection-less or connection-oriented service. Transport layer is responsible
to manage the connection.
}Flow
Control :-Transport layer is also responsible for
flow control which is performed end to end.
}Error
Control :-It
performs error checking. Transport layer at the sending device insure that the
entire message is delivered at the receiving machine without an error.
}Identifying
Service:-There are two types of service at the
transport layer one is TCP, which is connection oriented and second is UDP,
which is connectionless. Transport layer is responsible to identifying these
services and provide a TCP or UDP port number on the different services.There
are following deference between TCP and UDP.
Layer-3
Network Layer :-}The network
layer of the OSI model, provides an end-to-end logical addressing system so that a packet of data
can be routed across several layer 2 networks (Ethernet, Token Ring,Frame
Relay, etc.).
}Network
layer functions:
◦Logical
addressing.
◦Routing.
◦Handling
Congestion issue.
}Logical addressing:-When the packet is transmitted outside the local network packet required other
addressing scheme to identify source and destination. The network layer add
header that contains logical address (IP address) of source and destination.
}Routing:-Routing
is a process which define the proper path to transmit the data packet to the destination. Routing can be implemented from two types- static and dynamic. In
static routing route is determine by the network administrator, in dynamic
routing route is determine by the any routing protocol.
}Handling Congestion
issue:-Network
has certain capacity to deliver or handle number of packets, when the packets exceed the handling capacity then the network is unable to cop with them.
Layer-2 Data Link layer :-}This
is the second layer of OSI model. Data unit at this layer is called as “frame”.
}Data
Link Layer functions:
◦Framing.
◦Physical
Addressing.
◦Access
Control.
◦Flow
Control.
◦Error
Control.
}Framing:
– During
transmission, the value of the bits can change. It is also possible that the
number of bits received by the receiver may be different from the number of
bits send by the sender. To resolve this problem, the data link layer organizes
the bits into manageable data unit called as “frame”.
}Physical
Addressing:-Data
link layer adds header to the frame which contain the physical address of the
sender and receiver.
}Access
control:-The
data link layer provides access to particular devices to use the link at a
given time.
}Flow
Control:-The
rate of data transmission between two nodes should be controlled to keep both
the nodes in synchronization
}Error
control:-Error
control detects and corrects errors during transmission, if a frame is lost or
corrupt, the data link retransmit that frame.
Layer-1 Physical Layer :-}Physical
layer is the first or bottom most layer
of the OSI model. It define the electrical and mechanical specifications like
cables, connectors and signaling option of the medium. There are the following
functions of this layer.
}Physical
Layer functions:-
◦Characteristics
of media.
◦Encoding.
◦Transmission
rate.
◦Transmission
mode.
◦Topology.
}Characteristics of media :– It
defines the characteristics of the interface which is used for connecting the
devices.
}Encoding: –it change bit stream (0s and 1s) into
medium compatible signals.
}Transmission
rate :–it defines the number of bits per second
for transmission.
}Transmission
mode :– It defines the transmission between two
devices. There are different types of transmission modes-
◦Simplex :–In this mode only one device can send
and other can only receive.Ex.-Radio
& Transmitter.
◦Half
duplex :–Both devices can send and receive but
not at a given time.Ex.-walky
talky.
◦Full
duplex: – Both devices can send and receive at a
given time.Mobile
Phone.
ØTopology :–Define how the devices are connected to
build a network.
}Summary
Of Layers :-
Layer
7. Application :
◦Network
virtual terminal.
◦File
Transfers Access and Management (FTAM).
◦Ability
to print on a network.
◦Electronic
mail.
◦Browsing
the World Wide Web.
Layer
6. Presentation :
◦Translation.
◦Encryption.
◦Compression.
Layer
5. Session:
◦Dialog
Control.
◦Synchronization.
Summary
Of Layers :-
Layer
4. Transport :
◦Service
Point Addressing.
◦Segmentation
and reassembly.
◦Connection
control◦Flow
Control.
◦Error
control.
◦Identifying
Service
Layer
3. Network :
◦Logical
addressing
◦Routing
◦Handling
Congestion issue.
Summary
Of Layers :-
Layer
2. Data Link :
◦Framing.
◦Physical
Addressing.
◦Access
Control.
◦Flow
Control.
◦Error
Control.
Layer
1. Physical :
◦Characteristics
of media.
◦Encoding.
◦Transmission
rate.
◦Transmission
mode.
◦Topology.
UNIT-03
Topology :-•Topology is a physical structure of a
network. It describe the way in which the network devices are connected.
•There are four main
local area network (LAN) topologies:
1.Single Node Topology.
2.Bus Topology.
3.Star Topology.
4.Ring Topology.
•Other network topologies include:
1.Mesh.
2.Tree.
3.Hybrid.
4.Wireless.
Single Node Topology :-•It is the simplest topology. In this
topology two nodes are connected with each other using a cross over cable or
straight through cable in case of gigabyte Ethernet.
•Advantage of Single node topology:
o Easy to install, configure and
manage.
o Less expensive then other topology.
o Single cable is required.
•Disadvantage:
o Only two devices can be connected in
the entire network.
o One device is dependent to other
device for resources.
Single Node Topology :-•It is the simplest topology. In this topology two nodes
are connected with each other using a cross over cable or straight through
cable in case of gigabyte Ethernet.
•Advantage of Single node topology:
o Easy to install, configure and manage.
o Less expensive then other topology.
o Single cable is required.
•Disadvantage:
o Only two devices can be connected in the entire
network.
o One device is dependent to other device for resources.
Bus Topology :-•In this topology all devices shares
a common backbone cable. A thin Co-axial
cable used to connect all devices. Terminator is placed at
each end of the cable. The central cable is known as backbone of the network.
•Advantage of Bus Topology:
o Easy to connect a device to linear bus.
o Require less cable.
o Works better for smaller networks.
o Less expensive to star and ring topology.
•Disadvantage:
o Entire network gets affected if there is a break in the
main (backbone) cable.
o Terminators are required.
o Difficult to detect the faulty device.
o Limited number of devices can be connected.
o Expensive then single node topology.
Star Topology :-•In the star
topology multiple devices are connected to a central device, the
central device may be hub, switch or MAU (Multi Access Unit). Devices are
attached to the hub or switch by using copper cables or fiber
optic cables. Central device manages
and controls all the functions of the network.
•Advantage of Star Topology:
o Easy to install, configure and manage.
o Easy to detect faulty device.
o Easier to expand.
o Connecting or removing device does not affect the
entire network.
o There is a central device which provide centralized
management.
•Disadvantage:
o In case of hub increased devices causes traffic which
makes network slow.
o Requires more cable length than bus topology.
o Central device failure leads to network failure.
o More expensive.
Ring Topology :-•In ring topology all hosts are setup in a circular form
in which data travels around the ring in one direction. Each device act as a
repeater to keep the signals strong as it travels. The ring topology
can use twisted pair or fiber optic cabling. The ring topology
uses the base band signaling method. Media Access Control
(MAC) is used for token passing.
•Advantage of Ring Topology:
o Easier to manage as compared to Bus topology.
o Handles large volume of traffic.
o Very reliable and offer good speed.
o Provide a good communication over a long distance.
•Disadvantage:
o More cables requires as compared to bus topology.
o A specific Ring NIC (Network Interface Card) is
required.
o One faulty device affect the entire network.
Mesh Topology :-•In this topology each device is connected with each
other. Typically uses fiber optic cabling for redundant wide area
network (WAN) links. Provides multiple paths
to destinations for fault tolerance. Supports baseband and
broadband signals. It has many number of cables that can be
identify by:
•Number of Cables = n(n-1)/2
on= number of nodes or devices connected in the network.
•Advantage of Mesh Topology:
o Provides individual path for each device for sending
the data
o Entire Network does not get affected by one faulty
device.
o Centralized management is not required as in star
topology.
o Easy to detect faulty device.
•Disadvantage:
o More cables are required then the other topology.
o Each link from one device to another required an NIC
(Network Interface Card)
o Very expensive as compared to Bus, Star and Ring
Topology.
o Difficult to reconfigure.
Tree Topology :-•Tree topology is the combination of Bus and Star
topology. In this topology group of star networks are connected to the linear
bus backbone. Tree topology enables the user to expand and configure the
existing networking as per the requirement.
•Advantage of
Tree Topology:
o Point to point wiring for each device.
o Easy to detect a faulty device.
o Easy to expand a network
•Disadvantage:
o Difficult to configure as compared to other topology.
o Faulty in backbone affect the entire network.
o Overall length of each segment is limited.
Hybrid Topology :-•Hybrid topology is a network where two or more
topologies are connected in such a way that the resulting network does not have
one of the standard forms. This network is the combination of two or more
topologies.
•Advantage of
hybrid topology:
o Useful for implementing larger networks.
o Handles larger volume of traffic.
o Easy to detect faulty devices
•Disadvantage:
o More cabling is required as compare to all other
topologies.
o More expensive than all other topologies.
o Complex structure.
o Installation and configuration is difficult.
UNIT-04
TRANSMISSION MEDIA
Transmission Media :-*Networking involves connection on nodes
using a communication media or transmission media this media can be wired or
wireless.
*There are basically two types of
transmission media.
1.Wired medium or Guided medium.
2.Wireless medium or Un-guided medium.
Types Of Transmission Medium :-
Twisted Pair Cable :-*In
its simplest form, twisted-pair cable consists of insulated
strands
of copper wire twisted around each other.
*There
are two types of twisted pair cable.
1. UTP
(Unshielded Twisted Pair) Cable.
2. STP
(Shielded Twisted
Pair) Cable.
Twisted Pair Cable :-*In
its simplest form, twisted-pair cable consists
of two insulated strands of copper wire twisted around each other.
*There
are two types of twisted pair cable.
1. UTP
( Unshielded Twisted Pair ) cable.
2. STP
( Shielded Twisted
Pair ) cable.
UTP :-*UTP is the most popular and is generally the
best option for LAN.
The
quality of UTP may vary from telephone-grade wire to extremely high-speed
cable. The cable has four pairs of wires inside the jacket. Each pair is
twisted to help
eliminate interference from adjacent pairs and other electrical devices. The
tighter the twisting, the higher the supported transmission rate and the
greater the cost per foot.
The EIA/TIA (Electronic Industry Association/Telecommunication Industry
Association) has established standards of UTP and rated six categories of wire.
It’s maximum segment length is 100 meter and it uses RJ-45 connector.
Categories of Unshielded Twisted Pair :-
*Advantage Of UTP Cable :-
*cheapest form of cable and used for data
transmission in LAN.
*Easy to handle and install.
*Disadvantage :-
*Highly prone to external interference
like EMI (Electro magnetic Interference)
and RFI
(Radio Frequency Interference).
*Highly prone to cross talk.
*Less security of data transmission.
STP :-*Although UTP cable is the least expensive cable,
it may be susceptible to radio and electrical frequency interference.
If
you must place cable in environments with lots of potential interference, or if
you must place cable in extremely sensitive environments that may be
susceptible to the electrical current in the UTP, shielded twisted pair may be
the solution. Shielded cables can also help to extend the maximum distance of
the cables.
*Shielded twisted pair cable is available
in three different configurations:-
1.Each pair of wires is individually shielded
with foil.
2.There is a foil or braid shield inside the
jacket covering all wires (as a group).
3.There is a shield around each individual pair,
as well as around the entire group of wires (referred to as double shield
twisted pair).
*Advantage Of STP
Cable:-
*Better Protection from external
interference like EMI (Electro magnetic
Interference)
and RFI (Radio Frequency Interference).
*Secure data transmission then UTP.
*Disadvantage:-
*Costlier than UTP.
*Difficult to install as compared to UTP.
Co-axial Cable:-*Coaxial cabling has a single copper
conductor at its center. A plastic layer provides insulation between the center
conductor and a braided metal shield. The metal
shield helps to block any outside interference from fluorescent lights, motors,
and other computers.
Although
coaxial cabling is difficult to install, it is highly resistant to signal interference. In addition, it can support greater cable lengths between network
devices than twisted pair cable.
RG-58 (Radio frequency Government ) :-*RG-58/U is a type of coaxial cable often
used for low-power signal and RF connections.The outside diameter of RG-58 is around
0.2 inches (5 mm). Plain
RG-58
cable has a solid center conductor. RG-58 cable can be used for moderately high
frequencies. Its signal attenuation depends on the frequency, e.g. from 0.11
dB/m at 50 MHz to 1.4 dB/m at 2 GHz. It is also known as thinwire Ethernet
or 10Base2 where 10 denotes 10 MBPS data transfer rate, Base denotes Baseband
signaling and 2 denotes the maximum segment length of 200 meter (practically
185 meter).
RG-8 :-*It is approximately 1 cm in diameter and
mainly used as a backbone cable in Thick net. It can also carry signals at great
distance. The Thick wire Ethernet is also known as 10 Base 5 where
10 denotes 10 MBPS data transfer rate, Base denotes Base band signaling and 5 denotes
the maximum segment length of 500 meters. A maximum of 100 nodes can be attached to each 10 Base 5 segment.
RG-6 :-*RG-6/U is a common type of coaxial cable
used in a wide variety of residential and commercial applications. The term
"RG-6" itself is quite generic and refers to a wide variety of cable
designs, which differ from one another in shielding characteristics,center
conductor composition, and dielectric type.
*The most commonly recognized variety of
RG-6 is cable television (CATV) distribution coax, used to route cable
television signals to and within homes. CATV distribution coax typically has a
copper-coated steel center conductor and a combination aluminum foil/aluminum
braid shield, typically with low coverage (about 60%). RG-6 type cables are
also used in professional video applications, carrying either base band analog
video signals,
in
these applications, the center conductor is ordinarily solid copper.
RG59 :-*RG-59 is a specific type of coaxial cable,
often used for low-power video and RF signal connections. RG-59 is often used
at baseband video frequencies, such as composite video. It may also be used for
broadcast frequencies, but its high-frequency losses are too high to allow its
use over long distances.
RG-59 coaxial cable is commonly packed with consumer equipment, such as VCRs or
digital cable/satellite receivers. RG-59 is frequently used to synchronize two
digital audio devices, such as ADAT optical devices.This is called word clock.
FIBER OPTIC CABLE (FOC):-*An optical fiber cable is a cable
containing one or more optical fibers. The optical fiber elements are typically
individually coated with plastic layers and contained in a protective tube
suitable for the environment where the cable will be deployed.
*Optical fiber consists of a core and a cladding layer.
In practical fibers, the cladding is usually coated with a layer of acrylate
polymer or polyimide.
Individual coated fibers then
have
a tough resin buffer layer and core tube extruded around them to form the cable core.
*An optical fiber cable is a cable
containing one or more optical fibers. The optical fiber elements are typically
individually coated with plastic layers and contained in a protective tube
suitable for the environment where the cable will be deployed.
*Optical fiber consists of a core and a cladding layer.
In practical fibers, the cladding is usually coated with a layer of acrylate
polymer or polyimide.
Individual coated fibers then
have
a tough resin buffer layer and core tube extruded around them to form the cable core.
*In a fiber optic cable the electrical
signals are converted into light signals. An emitter is use to transmit the
signals and a light sensor (typically photo-diode)sense the signals and then
convert into its digital equivalent.
*Optical cables transfer data at the speed
of light in glass. This is typically around 180,000 to 200,000 km/s, resulting
in 5.0 to 5.5 microseconds of latency per km.
*Fiber Optic Cables are available in
different sizes with varying core and
cladding diameter . There are basically two types of Fiber Optic Cable.
1.Single Mode Fiber Optic Cable.
2.Multi Mode Fiber Optic Cable.
Single Mode Fiber Optic Cable:-*A type of cable that has only a single
path of glass fiber with a thin diameter. The diameter of core glass is
approximate 8.3 to 10 micrometer . Only a single light signal can be transmitted through it. This
type of cable can transmits data over long distance at higher speed.
Multi Mode Fiber Optic Cable :- *A type of cable that contains a glass
fiber with a larger diameter. Multiple of light signals can be transmitted
through it. This is approximate 62.5 to 125 micrometer cable. In this cable multiple light signals
can be transmitted using different path and length.
Twisted Pair Cabling :-*Twisted Pair cable is mainly use for LAN.
There are three way for cabling,
1.Straight Through cable.
2.Cross Over cable.
3.Roll over Cable (console cable).
Straight Through cable :-*This type cable is use to connect
different types of devices, such as connecting PC to Switch, PC to hub, Switch
to Router, PC to DSL modem, DSL modem to Switch etc.
Cross Over cable :-*This type cable is use to connect same
types of
devices, such as connecting PC to PC, Hub to hub, Switch to Switch,
Switch to Hub(hub is same as switch), Router to Router,DSL modem to DSL
modem etc.
Roll Over cable :-*This type cable is use to connect
the manageable networking device with the PC for configuring them. Such as
configure the Router, configure the manageable Switch ,Hub, access point and
modem. This cable is also called as console cable.
UNIT-05
NETWORKING DEVICES
Networking
Devices :-•Computer
networking devices are units that mediate data in a computer network.Computer networking
devices are also called network equipment, Intermediate Systems (IS)
or InterWorking Unit
(IWU).
Units which
are the last receiver or generate data are called hosts or data terminal equipment.
The most
common kind of networking hardware today is copper-based.
•Wireless
networking
has become increasingly popular, however, especially for portable and handheld
devices.
List
of Networking Devices :
1.Repeater.
2.Hub.
3.Bridge.
4.Switch.
5.Router.
6.Proxy.
7.Firewall.
Repeater :-•A
repeater is an electronic device that receives a signal and retransmits it at a
higher level or higher power, or onto the other side of an obstruction, so that
the signal can cover longer distances. There are two types of repeaters
one is analog that amplifies an input signal regardless of
its nature.
Second is digital that amplifies,
reshapes, retimes, or performs a combination of any of these functions on a
digital input signal for retransmission.
Advantage
and Disadvantage of Repeater :-
•Advantages:
–Makes
it easy to expand a network over a large distance.
–Connection
between various types of media e.g fibre optic, UTP, STP, coaxial cable is
possible.
•Disadvantages :
–Traffic
cannot be filtered to ease congestion.
–A
repeater cannot work across multiple network architectures.
Hub :-•A hub
is a
device for connecting multiple Ethernet devices together and making them act as
a single network segment. It has multiple input/output (I/O) ports, in which a
signal introduced at the input of any port, appears at the output of every port
except the original incoming. A hub works at the physical layer of the
OSI model.
Types
of Hub :-
1.Passive
Hub-: It
does not require power as they do not regenerate the received signal before
forwarding it.
2.Active
Hub-: It
regenerate the received signals before forwarding it to all the ports. The active hub required power supply.
3.Intelligent
Hub-: It
provides additional features to the active hub . It is also known as manageable
hub as each port of the hub can be configured by the network administrator according to the network requirement.
Bridge :-•A
network bridge is a network device that connects more than one network segment.
In the OSI model bridging acts in the first two layers. They do this
by sitting
between two physical network segments and managing the flow of
data between
them.
By
looking at the MAC address of the devices connected to each segment, bridges can elect to
forward the data.
Types
of Bridges :-Three
types of bridges are used in networks:
•➤Transparent
bridge—Derives
its name from the fact that the devices on the network are unaware of its existence. A transparent bridge
does
nothing except
block or forward data based on the MAC address.
•➤Source
route bridge—Used
in Token Ring networks. The source route bridge derives its name from the fact that the entire path that the packet
is to
take through the network is embedded within the packet.
•➤Translational
bridge—Used
to convert one
networking data
format to
another; for example, from Token Ring to Ethernet vice versa.
Switch :-•A
network switch is a computer networking device that links network segments or network devices. The term commonly refers to a multi-port network bridge that
processes and routes data at the data link layer (layer 2) of the OSI model.
Switches that additionally process data at the network layer (layer 3) and
above are often called layer-3 switches or multilayer switches. A switch is a
telecommunication device which receives a message from any device connected to
it and then transmits the message only to the device for which the message was
meant. This makes the switch a more intelligent device than a hub.
•A
switch uses one of three method of switching to send data over the network.
1.Store
and
forward-:
The switch
buffers and verifies each frame before forwarding it.
2.Cut
through-: The
switch reads only up to the frame's hardware address before starting to forward
it. Cut-through switches have to fall back to store and forward if the outgoing port is busy at the time the packet arrives. There is no error checking with
this method.
3.Fragment
free-: A
method that attempts to retain the benefits of both store and forward and cut
through. Fragment free checks the first 64 bytes of the frame, where addressing information is stored. According to Ethernet specifications, collisions should
be detected during the first 64 bytes of the frame, so frames that are in error
because of a collision will not be forwarded. This way the frame will always
reach its intended destination. Error checking of the actual data in the packet
is left for the end device.
Router :-•A
router is a device that forwards data packets between different
computer networks,
A router is connected to two or more data lines from different networks. When a
data packet comes in one of the lines, the router reads the address information
in the packet to determine its ultimate destination. Then, using information in
its routing table or routing policy, it directs the packet to the next network
on its journey. Routers perform the "traffic directing" functions on
the Internet. A data packet is typically forwarded from one router to another
through the networks that constitute the internetwork until it gets to its destination node.
Proxy
Server :-•In
computer networks, a proxy server is a server (a computer system or an
application) that acts as an intermediary for requests from clients seeking
resources from other servers. A client connects to the proxy server, requesting
some service, such as a file, connection,web page, or other resource available
from a different server and the proxy server evaluates the request as a way to
simplify and control their complexity. Today, most proxies are web proxies,
facilitating access to content on the World Wide Web.
Firewall :-•A
firewall can either be software-based or hardware-based and is used to help
keep a network secure. Its primary objective is to control the incoming and
outgoing network traffic by analyzing the data packets and determining whether
it should be allowed through or not, based on a predetermined rule set. Many
personal computer operating systems include software-based firewalls to protect
against threats from the public Internet. Many routers that pass data between
networks contain firewall components and, conversely, many firewalls can
perform basic routing functions.
Router
is intelligent
device which
routes
data to destination
computers. It helps in connecting two different logical and physical
networks
together. In small network server is connected to router along
with clients for
communication. Router uses software known as routing table. Routing
table is used to store source and destination address. Major companies which know for
manufacturing routers and wireless routers are TP Link, Cisco systems, Nortel, D
link etc.
proxy server :-A proxy
server is
a computer that offers a computer network service to allow clients to make
indirect network connections to other network services. A client connects to the proxy
server,
then requests a connection, file, or other resource available on a different server.
Firewall :- A firewall
is a system designed to prevent unauthorized access to or from a private network.
Firewalls
can be implemented in both
hardware and software
or a combination of both. Firewalls are frequently used to prevent
unauthorized Internet users from accessing private networks connected
to the Internet, especiallyintranets. All messages entering or leaving the intranet pass through the firewall, which
examines each message and blocks those that do not meet the
specified security criteria.
UNIT-06
Networking Protocols
Network
Protocol :-A
Protocol is set of rules that determine
how the data is transmitted over the network. It is a communication standard
followed by the networking devices and computers to communicate with each
other. Protocols exists at several levels such as hardware level and
application level.
}There
are different protocols as following-:
Types
of Protocols :-
1.NetBIOS/NetBEUI.
2.TCP/IP.
3.ARP/RARP.
4.ICMP/IGMP.
5.UDP.
6.IPX/SPX.
7.HDLC/SDLC.
NetBIOS/NetBEUI
(Network Basic Input Output System/Network BIOS
Extended User Interface) :-}It
provides services related to the session layer of the OSI model allowing applications on separate computers to communicate over a local area network. In
modern networks, NetBIOS normally runs over TCP/IP via the NetBIOS over TCP/IP
(NBT) protocol. This results in each computer in the network having both an IP
address and a NetBIOS name corresponding to a host name.
NetBIOS/NetBEUI
Services :-}NetBIOS
provides three distinct services:
◦Name
service for name registration and resolution.
◦Datagram
distribution service for connectionless
communication.
◦Session
service for connection-oriented
communication.
TCP/IP
(Transmission Control Protocol/Internet Protocol) :-}TCP
and IP were developed by a Department of Defense (DOD) research project to
connect a number different networks designed by different vendors into a
network of networks (the "Internet"). It is
successful because it delivered a few basic services
that everyone needs (file transfer, electronic mail, remote logon) across a
very large number of client and server systems.
}TCP/IP
provides end-to-end connectivity specifying how data should be formatted,
addressed, transmitted, routed and received at the destination. It has four
abstraction layers, each with its own protocols.
Comparison
of OSI and TCP/IP Model :-
Network
Interface Layer (Link Layer) :-}The
Network Interface is the physical and logical network
component used to interconnect hosts or nodes in the network and a link
protocol is a suite of methods and standards that operate only between adjacent
network nodes of a Local area network segment or a wide area network connection.
}Link-layer
protocols-:
There are following protocols supported by this
layer.
}ARP/RARP.
}NDP.
}Tunnels.
}PPP.
}Media
access control
(MAC) :-
◦DSL.
◦ISDN.
◦FDDI.
Internet
Layer :-}The
internet layer is a
group of protocols, and
specifications in the Internet protocol suite that are used to transport
datagrams (packets) from the originating host across network boundaries, if
necessary, to the destination host specified by a network address (IP address)
which is defined for this purpose by the Internet Protocol (IP). Internet-layer protocols use IP-based packets. The internet layer does not include the protocols that define communication between local network
nodes such as the local network topology, and
that usually use protocols that are based on the framing of packets specific to
the link types.
Protocols
of Internet Layer :-}The
primary protocols in the internet layer are the Internet protocol (IP). Itis
implemented in two versions, IPv4 and IPv6. The Internet Control Message
Protocol (ICMP) is primarily used for error and diagnostic functions. Different
implementations exist for IPv4 and IPv6. The Internet Group Management Protocol
(IGMP) is used by IPv4 hosts and adjacent multicast routers to establish
multicast group memberships.
Transport
Layer :-}In
computer networking, the transport layer provides
end-to-end communication services for applications
within a layered architecture of network
components and protocols. The transport layer provides convenient services such
as connection-oriented data stream support,reliability, flow control, and
multiplexing.
Protocols
of Transport Layer :-}The
most well-known transport protocol is the Transmission Control Protocol (TCP).
It is used for connection-oriented
transmissions, whereas the connectionless User Datagram Protocol (UDP) is used
for simpler messaging transmissions. Other
prominent protocols in this group are the Datagram Congestion Control Protocol
(DCCP) and the Stream Control Transmission Protocol (SCTP).
Application
Layer :-}In
computer network programming, the application layer is an abstraction layer
reserved for communications protocols and methods designed for process-to-process communications across an Internet Protocol (IP) computer
network. Application layer protocols use the underlying transport layer
protocols to establish host-to-host connections.
}In the
OSI model, the definition of its application layer is narrower in scope. It
separates functionality above the transport layer at two additional levels, the
session layer and the presentation layer. OSI specifies strict modular
separation of functionality at these layers and provides protocol implementations for each layer.
Protocols
of Application Layer :-
}Remote
login category :
◦Telnet
◦SSH
}File transfer
category :
◦FTP.
◦TFTP.
}Electronic
mail category :
◦SMTP.
◦IMAP.
◦POP.
}Support
services category :
◦DNS
◦RARP
◦BOOTP
◦SNMP
◦CMOT
}ARP/RARP :-}The
packets travel through various physical networks to reach the destination. At
the physical layer, routers and hosts are recognized by their physical
address(MAC) which is a local address. To communicate between the different
networks and to deliver a packet, both the physical address(MAC) and logical
(IP) address are required.
}The
user should be able to map a logical address to its corresponding physical
address and vice versa. Two protocols which can be used for mapping the logical
and physical addresses are ARP (address Resolution Protocol) and RARP (Reverse
Address Resolution Protocol).
}The
ARP maps the logical address to a physical address and the RARP maps the
physical address to a logical address.
ICMP/IGMP :-}In
the TCP/IP protocol suite, IP supports four protocols at the network layer. Two
among them are ICMP (Internet Control Message Protocol) and IGMP (Internet
Group Message Protocol). IP does not provide error reporting or
error-correcting mechanisms. It also has no mechanism for host and management queries.
ICMP is the protocol designed to overcome these drawbacks of the IP protocol.
It handles the problem such as rejection of datagrams or fragments, congestion
in the network and parameter problem of datagram header.
}Two
types of communications, unicast and multicast take place at the network layer.
In unicasting only the sender and receiver are involved in the communication
process where as in multicasting there is a single sender and multiple
recipients. IGMP protocol is used to send a message to multiple recipients at
the same time.
UDP :- }UDP
uses a simple transmission model with a minimum of protocol mechanism.
As this is normally IP over unreliable
media, there is no guarantee of delivery, ordering or duplicate protection. UDP
provides checksums for data integrity, and port numbers for addressing
different functions at the source and destination of the datagram.
}UDP is
suitable for purposes where error checking and correction is either not
necessary or performed in the application, avoiding the overhead of such
processing at the network interface level. Time-sensitive applications often
use UDP.
IPX/SPX
(Internetwork
Packet Exchange/Sequenced Packet Exchange)
:-}IPX
and SPX are networking protocols used primarily on networks using the Novell
NetWare operating systems. IPX is a network layer protocol used for connectionless communication whereas SPX is a transport layer protocol used
for connection-oriented communication. IPX/SPX provides same connection
services as TCP/IP with IPX working as IP and SPX working as TCP. IPX/SPX was
designed mainly for LAN whereas TCP/IP provides superior performance over WAN.
SDLC/HDLC
(Synchronous Data
Link Control :-
}SDLC
is a computer communications protocol.
SDLC supports multipoint links as well as
error correction. SDLC was
mainly used by IBM mainframe and midrange systems; however, implementations
exist on many platforms from many vendors. The use of SDLC is
becoming more and more rare,mostly
replaced by IP-based protocols or being tunneled through IP.
HDLC is
a bit-oriented code-transparent synchronous data link layer protocol developed
by the International Organization for Standardization(ISO). HDLC provides both
connection-oriented and connection less service.HDLC can
be used for point to multipoint connections, but is now used almost exclusively
to connect one device to another.
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