Transcript Computer Networks

Network Operating Systems :
Tasks and Examples
Instructor: Dr. Najla Al-Nabhan
2015
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Overview
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A network operating system (NOS) provides services to
clients over a network.
Both the client/server and peer-to-peer networking
models use network operating systems
NOSs must be able to handle typical network duties.
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Major Tools of NOS
Providing access to remote printers, managing which
users are using which printers when, managing how print
jobs are queued, and recognizing when devices aren't
available to the network
Enabling and managing access to files on remote systems,
and determining who can access what—and who can't
Granting access to remote applications and resources,
such as the Internet, and making those resources seem
like local resources to the user (the network is ideally
transparent to the user)
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Major Tools of NOS
Providing routing services, including support for major
networking protocols, so that the operating system
knows what data to send where
Monitoring the system and security, so as to provide
proper security against viruses, hackers, and data
corruption.
Providing basic network administration utilities (such as
SNMP, or Simple Network Management Protocol),
enabling an administrator to perform tasks involving
managing network resources and users.
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Networking Operating Systems (NOS)
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Computers have operating system software that allows
them to function. Without operating system instructions, a
computer is nothing more than a box with circuits. This is
the same with networks.
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Without a Network Operating System, a network is
nothing more than a number of computer devices
connected together. In order to transmit information and
communicate across a network, it is necessary to have a
Network Operating System.
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Tasks of NOS
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There are several different Network Operating Systems,
each with its own set of features and protocols.
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In order to transmit signals across a network, it is
necessary for the computer to communicate with its
modem or Network Interface Card.
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Network Operating Systems (NOS) provide the protocols
necessary to achieve this goal, but each different type of
modem or NIC needs to be able to communicate with the
particular NOS.
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Tasks of NOS
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It is therefore necessary to install the special software that
comes with the interface device.
This software is often referred to as a driver.
Computers made today usually come with both the
interface and necessary drivers installed.
Occasionally, you must install the modem or NIC yourself.
It is necessary to install the correct driver for that
interface device. Failure to so install the driver means that
the device will be unable to communicate over the
network or with the computer it is installed in.
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Tasks of NOS
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Network Operating Systems not only allow
communication across a network, they also allow a
network administrator to organize resources, control
access, and ensure that the network is operating efficiently.
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Terminologies
Driver—Also referred to as a device driver.
Software that allows communication between the
computer and an input/output port or external device.
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For example, a driver allows a network operating system
to communicate with the Network Interface Card.
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· Network Operating System—A combination
of software programs that instruct computers and
peripherals to accept requests for services
 across the network and then provide those services.
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Terminologies
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·User Account
An account used by Windows NT Server Operating
Systems and other NOS's that provides access to the
network. Each user on the network has his/her own
unique user name.
User Manager for Domains
A Windows NT Server application program that is
used to maintain individual and group user accounts.
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Terminologies
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Workgroup
Group of devices logically networked together as a single
unit. This simplifies network management by segmenting
and organizing users into defined groups that can be
managed as one. For example, everyone in the accounting
department may be considered a workgroup. One change
in security for the group changes security for all users.
File Servers: Store files created by application
programs.
Print Server: Accept print jobs sent by anyone across
the network.
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Types of NOSs
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There are several different Network Operating
Systems, each with its own set of features and
protocols.
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Sharing of network resources can be peer-to-peer or
client/server.
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Which NOS is the best is dependent on the end goal of
the network.
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Peer-to-Peer Networking
In peer-to-peer networking there is a
complete sharing of resources, both hardware
and software.
 All systems act as both users of resources and
providers of resources, but no one system is
dedicated to a single function.
 Peer-to-peer networks are generally best
suited to small networks and usually are less
expensive than client/server networks.
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Peer-to-Peer NOSs
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In a peer-to-peer network operating system users are allowed to share resources and
files located on their computers and access shared resources from others. This
system is not based with having a file server or centralized management source. A
peer-to-peer network sets all connected computers equal; they all share the same
abilities to use resources available on the network.
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Examples:
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AppleShare used for networking connecting Apple products.
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Windows for Workgroups used for networking peer-to-peer windows computers.
Advantages
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Ease of setup
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Less hardware needed, no server needs to be purchased.
Disadvantages
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No central location for storage.
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Lack of security that a client/server type offers.
Client/Server Networks
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Client/server networks dictate that systems are most
often dedicated to a single function.
They are either users of network resources or
providers of resources.
Client/server networks are typically more expensive
and robust than peer-to-peer networks and generally
support the building of larger networks.
Discussion of Internetworking Operating Systems will
cover the four major systems currently in use:
Windows, Novell, UNIX/LINUX, and Mac.
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Windows for Workgroups/Windows 95
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Windows for Workgroups, introduced in the early 90s
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Windows 95, introduced in 1995
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They are both considered peer-to-peer networking
systems and do not have the capabilities of true
internetworking operating systems.
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They are, however, inexpensive and more than adequate
for small workgroups wanting to share resources, use
email, and connect to the Internet.
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Client/Server NOSs
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Network operating systems can be based on a client/server
architecture in which a server enables multiple clients to share
resources.
Client/server network operating systems allow the network to
centralize functions and applications in one or more dedicated
file servers.
The server is the center of the system, allowing access to
resources and instituting security.
The network operating system provides the mechanism to
integrate all the components on a network to allow multiple
users to simultaneously share the same resources regardless of
physical location.
Client/Server NOSs
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Examples:
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Advantages
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Novell NetWare
Windows Server
Banyan VINES
Centralized servers are more stable.
Security is provided through the server.
New technology and hardware can be easily integrated into the system.
Servers are able to be accessed remotely from different locations and types of
systems.
Disadvantages
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Cost of buying and running a server are high.
Dependence on a central location for operation.
Requires regular maintenance and updates.
Routers NOSs
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Network operating systems can be embedded in a router or hardware
firewall that operates the functions in the network layer (layer 3) of the OSI
model.
Examples:
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JUNOS, used in routers and switches from Juniper Networks,
Cisco IOS (formerly "Cisco Internetwork Operating System").
TiMOS, used in routers from Alcatel-Lucent
VRP (Versatile Routing Platform), used in routers from Huawei
RouterOS, software which turns a PC or MikroTik hardware into a dedicated router
ZyNOS, used in network devices made by ZyXEL.
ExtremeXOS, used in network devices made by Extreme Networks. Also called
EXOS.
Embedded Linux, in distributions like Openwrt and DD-WRT which run on low-cost
platforms such as the Linksys WRT54G.
Quiz
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next lecture
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