Service initialization and service termination
of workstations
Network Interfaces
The network interfaces provide the low-level
subnet protocols and basic translation for bridging
hardware drivers with the network operating system.
In sophisticated systems, the network interfaces can
also provide for bridging a new network into an
operating network without having to rebuild the
operating system.
File Systems
The file system controls the way the data is
organized, stored, and retrieved from the storage
systems available to the network. The files may be
stored on hard drives, RAM disks, or optical storage
devices, such as CD-ROM or write once, read many
(WORM) drives.
File systems are generally designed to provide
universal applicability.
This means that the file
system can be compatible with any application
program’s expectation of file input/output protocol.
When adaptable interfaces are used, the file system
can appear to emulate a number of different file
systems.
System Extensions
The system extensions define the openness of the
network operating system and are used by third party
developers to produce add-on products.
The
extensions are usually high-level protocol handlers
that perform operations, such as file access protocol
translations required by different operating systems.
The extensions available also include network
management, system tools, and data-base services.
System Services
Network system services contain all services that
are not easily defined by any of the other areas of the
network. Examples of network services are security,
system reliability features, error conditions, and
access violations.
NETWORK
OPERATING
SYSTEMS
SOFTWARE
The most important job of a network operating
system (NOS) is to provide file service for the
attached computers. This allows information retrieval
and usage and the storage of data in a shared
environment. A NOS manages the other resources
shared by the network and provides the following
functions:
Directory structure for shared hard disk
storage devices
File service for sharing and using data
Interface to the network for application
software/programs
The means by which the network manager
manages the network and its users
Network security and data protection
Communications with other networks
The types of network operating systems include
full-featured, low-cost, and zero-slot operating
systems.
Full-Featured Network Operating Systems
Most full-featured network operating systems
allow for high performance, flexibility, and excellent
security measures. They require a LAN administrator.
They require network interface cards. Also, they can
be quite costly. Examples of a fill-featured NOS are
EtherNet, Novell’s NetWare, 3Com’s 3+Share, IBM’s
Token Ring Network, and Banyan’s Vines.
Low-Cost Network Operating Systems
Most low-cost network operating systems differ
from full-featured systems only in the maximum
number of users accommodated on the network and
the number of security levels incorporated into the
operating system. In general, they are much lower in
cost and are easier to install and use. Examples of
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