Computer
network is a collection of interconnected computers, which are able to exchange
information between each other. In other words, it is a collection of computers
and peripheral devices connected by communication links that allows the network
components to work together autonomously.
What is a protocol?
A
Network protocol is a specialized electronic language that enables network
computers to communicate. Different types of computers, using different
operating systems, can communicate with each other, and share information as
long as they follow the network protocols. A protocol suite is a set of related
protocols that come from a single developer or source.
A
protocol stack is a set of two or more protocols that work together, with each
protocol covering a different aspect of data communications.
What is client server technology?
It is a network of shared or
distributed computing in which the tasks and computing power are split between
the servers and clients. The servers store and process data common to the users
across the organization and these data can be accessed by any client.
In this networking requests are
made by different clients to the server.
Server then process the request and provide the desired result to the client.
All the information are stored with the server. Server acts like a database
which extract the relevant information to the client. In this way it becomes
fast and client becomes thin.
The client server architecture
is versatile, supports GUI and has modular infrastructure. The technology is
described as a cost reduction technology. It includes fourth generation
languages, relational databases, distributing computing etc.
What are the basic elements of data
communication system?
1) Message - the data or
information that is to be sent. It could be text, picture, etc.
2) Sender - a device that
transmits the message. It could be a computer, telephone, etc.
3) Receiver - a device that
receive the message. It could be the same components as sender.
4) Medium - is the path through
that the data is sent, wire, air, light, etc.
5) Protocol - Set of rules and
regulations that should be observed by the devices.
What are the components in data
communication system?
5 Major components of data
communication systems are :-
1. Message Message is the
information to be communicated. The message may consist of text, numbers,
pictures etc.
2. Sender Sender is a device
that sends the message. Normally, computer is used as sender in data
communication systems. It is also called source or transmitter.
3. Medium Medium is the physical
path that connects sender and receiver. It is used to transmit data. The medium
can be a copper wire, a fiber optic cable, microwaves etc.
4. Receiver Receiver is a device
that receives message. It is also called sink. The receiver can be computer,
printer, or another computer related device. It must be proficient of
accommodating the message.
5. Protocol A protocol is a set
of policies that administrates data communication. It represents an agreement between
communication devices. Devices cannot communicate without protocol.
What is data communication?
Data communication refers to the
exchange of data between a source and a receiver. Data communication is said to
be local if communicating devices are in the same building or a similarly
restricted geographical area.
The meanings of source and
receiver are very simple. The device that transmits the data is known as source
and the device that receives the transmitted data is known as receiver. Data
communication aims at the transfer of data and maintenance of the data during
the process but not the actual generation of the information at the source and
receiver.
What does Distributed Network mean?
A distributed network is a type
of computer network that is spread over different networks. This provides a
single data communication network, which can be managed jointly or separately
by each network. Besides shared communication within the network, a distributed
network often also distributes processing.
What Is Distributed Computing?
What you need is a distributed
computing system. A distributed system uses software to coordinate tasks that
are performed on multiple computers simultaneously. The computers interact to
achieve a common goal, and they interact by sending each other messages.
In the case of the software you
developed, the actual calculations need to be broken up into separate elements
that can be run on different computers. Some calculations may be entirely
sequential, meaning that you can only go to step two after step one has been
completed. However, some calculations may be able to run in parallel, meaning
that you can break them up into elements, run them separately but at the same
time, and then combine the results.
Advantages and Disadvantages of
Different Network Topologies
Network
topologies describe the ways in which the elements of a network are connected.
They describe the physical and logical arrangement of network nodes. Let us
look at the advantages different network topologies offer, and their
shortfalls.
Advantages
and Disadvantages of...
o
Bus Topology
o
Ring Topology
o
Mesh Topology
o
Star Topology
o
Tree Topology
o
Hybrid Topology
Bus Topology
Advantages
▸ It is
easy to set up, handle, and implement.
▸ It is
best-suited for small networks.
▸ It
costs very less.
Disadvantages
▸ The
cable length is limited. This limits the number of network nodes that can be
connected.
▸ This
network topology can perform well only for a limited number of nodes. When the
number of devices connected to the bus increases, the efficiency decreases.
▸ It is
suitable for networks with low traffic. High traffic increases load on the bus,
and the network efficiency drops.
▸ It is
heavily dependent on the central bus. A fault in the bus leads to network
failure.
▸ It is
not easy to isolate faults in the network nodes.
▸ Each
device on the network "sees" all the data being transmitted, thus
posing a security risk.
Ring Topology
Advantages
▸ The
data being transmitted between two nodes passes through all the intermediate nodes.
A central server is not required for the management of this topology.
▸ The
traffic is unidirectional and the data transmission is high-speed.
▸ In
comparison to a bus, a ring is better at handling load.
▸ The
adding or removing of network nodes is easy, as the process requires changing
only two connections.
▸ The
configuration makes it easy to identify faults in network nodes.
▸ In
this topology, each node has the opportunity to transmit data. Thus, it is a
very organized network topology.
▸ It is
less costly than a star topology.
Disadvantages
▸ The
failure of a single node in the network can cause the entire network to fail.
▸ The
movement or changes made to network nodes affect the entire network's
performance.
▸ Data
sent from one node to another has to pass through all the intermediate nodes.
This makes the transmission slower in comparison to that in a star topology.
The transmission speed drops with an increase in the number of nodes.
▸ There
is heavy dependency on the wire connecting the network nodes in the ring.
Mesh Topology
Advantages
▸ The
arrangement of the network nodes is such that it is possible to transmit data
from one node to many other nodes at the same time.
▸ The
failure of a single node does not cause the entire network to fail as there are
alternate paths for data transmission.
▸ It
can handle heavy traffic, as there are dedicated paths between any two network
nodes.
▸
Point-to-point contact between every pair of nodes, makes it easy to identify
faults.
Disadvantages
▸ The
arrangement wherein every network node is connected to every other node of the
network, many connections serve no major purpose. This leads to redundancy of
many network connections.
▸ A lot
of cabling is required. Thus, the costs incurred in setup and maintenance are
high.
▸ Owing
to its complexity, the administration of a mesh network is difficult.
Star Topology
Advantages
▸ Due
to its centralized nature, the topology offers simplicity of operation.
▸ It
also achieves isolation of each device in the network.
▸
Adding or removing network nodes is easy, and can be done without affecting the
entire network.
▸ Due
to the centralized nature, it is easy to detect faults in the network devices.
▸ As
the analysis of traffic is easy, the topology poses lesser security risk.
▸ Data
packets do not have to pass through many nodes, like in the case of a ring
network. Thus, with the use of a high-capacity central hub, traffic load can be
handled at fairly decent speeds.
Disadvantages
▸
Network operation depends on the functioning of the central hub. Hence, central
hub failure leads to failure of the entire network.
▸ Also,
the number of nodes that can be added, depends on the capacity of the central
hub.
▸ The
setup cost is quite high.
Tree Topology
Imagine
a hierarchy of network nodes, with the root node serving client nodes, that in
turn serve other lower-level nodes. The top-level node is mostly a mainframe
computer while other nodes in the hierarchy are mini or microcomputers. In this
arrangement, the node at each level could be forming a star network with the
nodes it serves. In this case, the structure combines star and bus topologies
and inherits their advantages and disadvantages.
Advantages
▸ The
tree topology is useful in cases where a star or bus cannot be implemented
individually. It is most-suited in networking multiple departments of a
university or corporation, where each unit (star segment) functions separately,
and is also connected with the main node (root node).
▸ The
advantages of centralization that are achieved in a star topology are inherited
by the individual star segments in a tree network.
▸ Each
star segment gets a dedicated link from the central bus. Thus, failing of one
segment does not affect the rest of the network.
▸ Fault
identification is easy.
▸ The
network can be expanded by the addition of secondary nodes. Thus, scalability
is achieved.
Disadvantages
▸ As
multiple segments are connected to a central bus, the network depends heavily
on the bus. Its failure affects the entire network.
▸ Owing
to its size and complexity, maintenance is not easy and costs are high. Also,
configuration is difficult in comparison to that in other topologies.
▸
Though it is scalable, the number of nodes that can be added depends on the
capacity of the central bus and on the cable type.
Hybrid Topology
A
hybrid topology combines two or more topologies and is meant to reap their
advantages. Obviously, the advantages and disadvantages of a hybrid topology
are a combination of the merits and demerits of the topologies used to
structure it.
Go
through types of network topologies for a detailed description of the various
network topologies in use today.
What Is Server ?
Servers
are physically like other computers where their hardware configuration is
specifically optimized to make them most appropriate for their role. In many
servers the hardware installed is alike the hardware of any other normal
computer but the software run in the server is far more different form the
software that are installed in other computers.
Additional processing, storage capacity and memory are commonly
configured in the network servers to improve its capacity to handle clients –
other computers on the network.
The
underlying hardware or software for a system that drives the server is called a
server platform. Instead of operating system, the term server platform is used.
What is Client ?
A
client is a computer that retrieves information from or uses resources provided
by the server or main computer. Many corporate networks are comprised of a
client computer at each of the employees' desks. Each of these computers
connects to a central server or mainframe, which allows processing to be done
on the client side instead of the server side and reduces the processing
requirements of the server.
Client
is also another name for a software program used to connect to a server.
DIFFERENT TYPES OF NETWORKS
o
Local
Area Network (LAN)
o
Metropolitan
Area Network (MAN)
o
Wide
Area Network (WAN)
Local
Area Network (LAN)
A LAN is a network that is used
for communicating among computer devices, usually within an office building or
home.4
• LAN’s enable the sharing of
resources such as files or hardware devices that may be needed by multiple
users
• Is limited in size, typically
spanning a few hundred meters, and no more than a mile.
• Is fast, with speeds from 10
Mbps to 10 Gbps
• Requires little wiring,
typically a single cable connecting to each device
• Has lower cost compared to
MAN’s or WAN’s
• LAN’s can be either wired or
wireless. Twisted pair, coax or fiber optic cable can be used in wired LAN’s.
• Every LAN uses a protocol – a
set of rules that governs how packets are configured and transmitted.
• Nodes in a LAN are linked
together with a certain topology. These topologies include:
– Bus
– Ring
– Star
• LANs are capable of very high
transmission rates (100sMb/s to Gb/s).
Metropolitan
Area Network (MAN)
A metropolitan area network
(MAN) is a large computer network that usually spans a city or a large campus.
• A MAN is optimized for a
larger geographical area than a LAN, ranging from several blocks of buildings
to entire cities.
• A MAN might be owned and
operated by a single organization, but it usually will be used by many
individuals and organizations.
A MAN often acts as a high speed
network to allow sharing of regional resources.
• A MAN typically covers an area
of between 5 and 50 km diameter.
• Examples of MAN: Telephone
company network that provides a high speed DSL to customers and cable TV
network.
Wide
Area Network (WAN)
WAN covers a large geographic
area such as country, continent or even whole of the world.
• A WAN is two or more LANs
connected together. The LANs can be many miles apart.
• To cover great distances, WANs
may transmit data over leased high-speed phone lines or wireless links such as
satellites.
• Multiple LANs can be connected
together using devices such as bridges, routers, or gateways, which enable them
to share data.
• The world's most popular WAN
is the Internet.
No comments:
Post a Comment