What is a Network Operating System?
Unlike operating systems, such as DOS and
Windows, that are designed for single users to
control one computer, network operating systems
(NOS) coordinate the activities of multiple
computers across a network. The network
operating system acts as a director to keep the
network running smoothly.
The two major types of network operating
systems are:
Peer-to-Peer
Peer-to-peer network operating systems allow
users to share resources and files located on
their computers and to access shared resources
found on other computers. However, they do not
have a file server or a centralized management
source (See fig. 1). In a peer-to-peer network,
all computers are considered equal; they all
have the same abilities to use the resources
available on the network. Peer-to-peer networks
are designed primarily for small to medium local
area networks. AppleShare and Windows for
Workgroups are examples of programs that can
function as peer-to-peer network operating
systems.
Fig. 1. Peer-to-peer network
Advantages of a peer-to-peer network:
- Less initial expense - No need for a
dedicated server.
- Setup - An operating system (such as
Windows XP) already in place may only need
to be reconfigured for peer-to-peer
operations.
Disadvantages of a peer-to-peer network:
- Decentralized - No central repository
for files and applications.
- Security - Does not provide the security
available on a client/server network.
Client/Server
Client/server network operating systems allow
the network to centralize functions and
applications in one or more dedicated file
servers (See fig. 2). The file servers become
the heart of the system, providing access to
resources and providing security. Individual
workstations (clients) have access to the
resources available on the file servers. The
network operating system provides the mechanism
to integrate all the components of the network
and allow multiple users to simultaneously share
the same resources irrespective of physical
location. Novell Netware and Windows 2000 Server
are examples of client/server network operating
systems.
Fig. 2. Client/server network
Advantages of a client/server network:
- Centralized - Resources and data
security are controlled through the server.
- Scalability - Any or all elements can be
replaced individually as needs increase.
- Flexibility - New technology can be
easily integrated into system.
- Interoperability - All components
(client/network/server) work together.
- Accessibility - Server can be accessed
remotely and across multiple platforms.
Disadvantages of a client/server network:
- Expense - Requires initial investment in
dedicated server.
- Maintenance - Large networks will
require a staff to ensure efficient
operation.
- Dependence - When server goes down,
operations will cease across the network.
Examples of network operating systems
The following list includes some of the more
popular peer-to-peer and client/server network
operating systems.
