Download Network 1 S03

Network 1
S03
By Dr-Ahmad AA Alkhatib
Network Architecture
There are several ways in which a network can be designed: peer-to-peer,
client/server and mainframe systems. These are also referred to as different
types of network architecture.
In a peer-to-peer, or P2P, network, tasks are allocated among all the
computers in the network. There is no real hierarchy among the computers,
and all of them are considered equal. This is also referred to as a
'distributed architecture,' or 'workgroup without hierarchy.' This is the
simplest type of architecture since it does not have a central server.
Peer-to-Peer vs. Client/Server Architecture
In peer-to-peer networks, the connected computers have no centralized
authority. From an authority viewpoint, all of these computers are
equal. In other words, they are peers. If a user of one computer wants
access to a resource on another computer, the security check for
access rights is the responsibility of the computer holding the
resource.
Each computer in a peer-to-peer network can be both a client that
requests resources and a server that provides resources.
In peer-to-peer network each user is responsible for local backup.
Security considerations are minimal. A limited number of computers are
involved.
Peer-to-Peer vs. Client/Server Architecture
In a peer-to-peer network, a group of computers is connected together so
that users can share resources and information. There is no central location
for authenticating users, storing files, or accessing resources. This means
that users must remember which computers in the workgroup have the
shared resource or information that they want to access. It also means that
users must log on to each computer to access the shared resources on that
computer.
Peer-to-Peer vs. Client/Server Architecture(Cont…)
Peer-to-Peer vs. Client/Server Architecture
In most peer-to-peer networks, it is difficult for users to track where
information is located because data is generally stored on multiple
computers. This makes it difficult to back up critical business information,
and it often results in small businesses not completing backups. Often,
there are multiple versions of the same file on different computers in the
workgroup.
In some peer-to-peer networks, the small business uses one computer that
is running a client operating system, such as Microsoft Windows 98 or
Windows XP Professional, as the designated "server" for the network.
Although this helps with saving data in a central location, it does not
provide a robust solution for many of the needs of a small business, such as
collaborating on documents.
Peer-to-Peer vs. Client/Server Architecture
In a client/server network, a number of network clients or workstations
request resources or services from the network. One or more network
servers manage and provide these resources or services. The clients are
computers that depend on the server for data and software. In a mainframe
system, all the processing is done by a single, very powerful computer.
Individual terminals are used to access the mainframe computer but don't
run any applications themselves.
Peer-to-Peer vs. Client/Server Architecture(Cont…)
In contrast to a peer-to-peer network, a client/server network uses a network operating system designed to
manage the entire network from a centralized point, which is the server. Clients make requests of the
server, and the server responds with the information or access to a resource.
Peer-to-Peer vs. Client/Server Architecture
Most Local Area Networks (LANs) use a client/server architecture. Network
servers contain data and software applications that can be accessed by the
clients in the network. Network servers are also referred to as 'computer
servers,' or simply 'servers'. Sometimes a server is described in terms of the
specific service it provides, such as an e-mail server, print server or storage
server. Many servers, however, provide all these services.
Peer-to-Peer vs. Client/Server Architecture
Servers are typically computers with more processing speed, memory and
hard disk space than a regular desktop computer. Network servers run their
own operating system that manages various network tasks, as well as
services that run on the network. Depending on the need for network
storage and services, a single network may use anywhere from only one to a
large number of servers.
Peer-to-Peer vs. Client/Server Architecture
'Clients' are hardware devices that provide end users with access to data
and services on the server. Desktop and laptop computers are examples of
typical clients. You can also use these devices more or less independently.
For example, you can open up software applications, create and edit
documents and save files on the local storage medium, such as a hard disk.
However, in a typical client/server network, a number of essential tasks are
not performed by the clients alone. Some typical examples are:A printer is
connected to the network, and to print a document, the client sends a print request to the
server
E-mail messages are stored on the server, and the client is used to view and manage
messages
Very large databases are stored on the server, and the client accesses these without
copying them onto the local hard drive
Peer-to-Peer vs. Client/Server Architecture
There are a number of different types of clients. Stand-alone desktop and
laptop computers that are used as clients are known as 'fat clients.' These
computers can run programs on their own, have a local hard drive for
storage and only use the network for certain tasks.
'Thin clients', on the other hand, have their own processor but may not have
a hard drive. They depend entirely on the network to access software
applications and data. 'Dumb terminals' have a monitor, keyboard and a
minimum amount of hardware to connect to the network. All the processing
is done by the server. Good examples of thin clients are computers at a
public library. Typically, they are only used to access the library's catalog,
and they don't run any other applications.
Peer-to-Peer vs. Client/Server Architecture
In a server-based network, the server is the central location where users
share and access network resources . This dedicated computer controls the
level of access that users have to shared resources. Shared data is in one
location, making it easy to back up critical business information. Each
computer that connects to the network is called a client computer. In a
server-based network, users have one user account and password to log on
to the server and to access shared resources. Server operating systems are
designed to handle the load when multiple client computers access serverbased resources.
Mainframe Systems
Computer networks have become part of everyday life. Take the example of
a bank. Every moment of the day, customers carry out transactions deposits, withdrawals, transfers, etc. A typical national bank can easily have
over one million customers, and they can access their account information
at hundreds of different branches, thousands of ATM machines and from
just about any computer or smartphone. The account information for each
customer needs to be kept up-to-date in real time.
Consider for a moment what kind of computer you would need to manage all
this account information. You probably get the picture - this is not the kind
of computer you can buy at your local electronic store. You need a
mainframe.
Mainframe Systems
A mainframe is a powerful computer to handle all the processing of large
amounts of data. They are typically used by large companies or government
agencies. The term originates from the large cabinets that were used to
store the processor, memory and other parts of early computers. The term
continues to be used to distinguish between very large and powerful
computing systems and regular personal computers (PCs).
Some computing tasks require the power of multiple computers. Learn how
distributed computing coordinates tasks performed on multiple computers
at the same time.
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.
Recap -Different Types of Networks
There are a number of different ways to describe computer networks,
including network size, transmission media, management method and
network topology. Network size relates to the geographic area occupied by
the computers and the network and the behavior of the computers when
data is shared. For example, a local area network, or LAN, consists of a
computer network at a single site, typically an individual building. A wide
area network, or WAN, occupies a very large area, such as an entire country
or the entire world. The Internet is the best-known example of a WAN.
The transmission media of a computer network describes the material
substances that carry energy waves, which include the data being
transferred. The two main categories are wired connections, which use
physical cables, and wireless connections, which use electromagnetic
waves and do not require a physical medium. The most commonly used
wired connections use twisted-pair cables, coaxial cables and fiber optic
cables. The most commonly used wireless connections use radio waves,
microwaves and infrared waves.
Computers in a network are connected in some logical manner, referred to
as network topology or network architecture. Learn about the different types
of network architecture.