Part-II
Read Ist Part [What is a computer Network] in your group's
mail
dated: Mon May 29, 2006.
OR Click here to read in our group
Categories of Network:
Network can be divided in to two main categories:
Peer-to-peer.
Server – based.
In peer-to-peer networking there are no dedicated servers or
hierarchy among the computers. All of the computers are
equal and
therefore known as peers. Normally each computer serves as
Client/Server and there is no one assigned to be an
administrator
responsible for the entire network.
Peer-to-peer networks are good choices for needs of small
organizations where the users are allocated in the same
general
area, security is not an issue and the organization and the
network
will have limited growth within the foreseeable future.
The term Client/server refers to the concept of sharing the
work
involved in processing data between the client computer and
the most
powerful server computer.
The client/server network is the most efficient way to
provide:
Databases and management of applications such as
Spreadsheets,
Accounting, Communications and Document management.
Network management.
Centralized file storage.
The client/server model is basically an implementation of
distributed or cooperative processing. At the heart of the
model is
the concept of splitting application functions between a
client and
a server processor. The division of labor between the
different
processors enables the application designer to place an
application
function on the processor that is most appropriate for that
function. This lets the software designer optimize the use
of
processors--providing the greatest possible return on
investment for
the hardware.
Client/server application design also lets the application
provider
mask the actual location of application function. The user
often
does not know where a specific operation is executing. The
entire
function may execute in either the PC or server, or the
function may
be split between them. This masking of application function
locations enables system implementers to upgrade portions of
a
system over time with a minimum disruption of application
operations, while protecting the investment in existing
hardware and
software.
The OSI Model:
Open System Interconnection (OSI) reference model has become
an
International standard and serves as a guide for networking.
This
model is the best known and most widely used guide to
describe
networking environments. Vendors design network products
based on
the specifications of the OSI model. It provides a
description of
how network hardware and software work together in a layered
fashion
to make communications possible. It also helps with trouble
shooting
by providing a frame of reference that describes how
components are
supposed to function.
There are seven to get familiar with and these are the
physical
layer, data link layer, network layer, transport layer,
session
layer, presentation layer, and the application layer.
Physical Layer, is just that the physical parts of the
network such
as wires, cables, and there media along with the length.
Also this
layer takes note of the electrical signals that transmit
data
throughout system.
Data Link Layer, this layer is where we actually assign
meaning to
the electrical signals in the network. The layer also
determines the
size and format of data sent to printers, and other devices.
Also I
don't want to forget that these are also called nodes in
the
network. Another thing to consider in this layer is will
also allow
and define the error detection and correction schemes that
insure
data was sent and received.
Network Layer, this layer provides the definition for the
connection
of two dissimilar networks.
Transport Layer, this layer allows data to be broken into
smaller
packages for data to be distributed and addressed to other
nodes
(workstations).
Session Layer, this layer helps out with the task to carry
information from one node (workstation) to another node
(workstation). A session has to be made before we can
transport
information to another computer.
Presentation Layer, this layer is responsible to code and
decode
data sent to the node.
Application Layer, this layer allows you to use an
application that
will communicate with say the operation system of a server.
A good
example would be using your web browser to interact with the
operating system on a server such as Windows NT, which in
turn gets
the data you requested.
Continued...READ IN NEXT MAIL: "Network
Architectures"
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