Transcript Document

Chapter 11
Network Operations
Introduction
• Look at:
– Network Operating Systems (11.1)
– Software Components of Networking (11.2)
– Installing a Network Operating System
(11.3)
– Understanding Basic Network Services
(11.4)
Network Operating Systems
• Network operating systems (NOSs)
have existed for more than 30 years
• In the early 1980s, NOSs were mainly
research projects
• Many of the original ones were actually
a type of software package added to
standalone operating systems rather
than a true NOS
Network Operating Systems
• The first networks allowed computers to
exchange data by means of a basic network
protocol
• The application programs running on these
computers controlled the exchange of data
and used the network to share data for
specific purposes
• One of the first successful attempts at
integrating networking extensions into an
operating system resulted in Berkeley Unix
also known as BSD
Network Operating Systems
• As the networked computers increased, some
type of uniform networking support in the
operating system would be necessary
• A user could only use a computer on which
he or she had an account, so users would
want accounts on all computers
• In order to work collectively users had to
move files back and forth
• This required they know each other’s
passwords and manually track the versions of
the files
Network Operating Systems
• The first popular commercial network
operating system was SunOS
• Two major improvements were present
in SunOS:
– A network file system allowing a file that
exists on one computer to be visible from
other computers
– A directory service
Network Operating Systems
• Some of the commonly available
network operating systems include:
– Linux
– Novell NetWare
– SunOS/Solaris
– FreeBSD
– Unix
– Windows
Network Operating Systems
• Current operating systems provide a large
number of services to provide application
programs with a unified view of the network
• The basic functions of an operating system
include:
– Directing and controlling activities of a
computer’s hardware components
– Coordinating the interaction between
software applications and computer
hardware
Network Operating Systems
• A network operating system utilizes
device drivers as well as protocol stacks
for networking hardware
• Typically, there is at least one shared
server providing access to files and
shared hardware resources
• It coordinates the activities of multiple
computers across a network
Network Operating Systems
• The network operating:
• Advertises and manages resources
from a centralized directory
• Provides mechanisms to easily add and
remove services
• Reconfigures the resources
• Has the ability of supporting multiple
services of the same kind
Network Operating Systems
• Besides the mechanisms for supporting
services, the NOS also needs to draw
as much power out of its hardware as
possible
• One way of doing this is through a
process called multitasking
• Multitasking is doing more than one
thing at a time
Network Operating Systems
• There are two types of multitasking:
– Pre-emptive, where the processes are
assigned CPU time slices by the operating
system
– Cooperative, where the operating system
has no control over the processes
• When determining which operating
system to use, preemptive multitasking
should be a key factor
Software Components of Networking
• Because a NOS provides a large variety
of services and functions, there are
quite a few software components that
help make up a network operating
system
• Some of those include:
– Naming and directory services,
– Client and server network software,
– Drivers and stacks
Software Components of Networking
• For the devices on the network to
communicate, they use a special interface
card
• Before the card can be used, a software or
device driver must be installed on the
computer
• A driver is a program that interacts with either
a particular device or type of software
Software Components of Networking
• Some of the driver technologies are:
– The Network Device Interface System
(NDIS)
– Open Data-Link Interface (ODI)
– Win32 Driver model (WDM)
• Every NIC must have at least one
protocol stack bound to it
Software Components of Networking
• A stack is a set of network protocol
layers that work together
• The set of TCP/IP protocols that define
communication over the Internet is the
most common stack
• TCP/IP stacks have been written for
NDIS, ODI and WDM driver interfaces
Software Components of Networking
• Client/server network operating systems
allow the network to centralize services and
applications in one or more dedicated servers
• There is usually a clear distinction between
client and server NOS software
• Client software is a bit simple
• Server software is more complex and its
implementation depends on the type of NOS
Software Components of Networking
• The advantages of a client/server
network include:
– Centralization
– Interoperability
– Scalability
– Flexibility
– Expense
Software Components of Networking
• The advantages of a client/server
network include:
– Dependence
– Administration
• The client NOS makes network
resources look to the user like they are
local
Software Components of Networking
• The server NOS provides the following
functions:
– Manages a directory that contains user
permissions to resources
– Supports file access compatible with
various client operating systems
– Supports consistent user environment
– Provides interfaces to Internet Services
– Manages shareable mass storage
Software Components of Networking
• Some of the advantages and
disadvantages of a peer-to-peer
network are:
– Less initial expense
– Setup
– Decentralization
– Security
– Performance
Software Components of Networking
• The most important component of a NOS is
redirection
• Network operating systems depend heavily
on redirection
• The redirector operates at the Presentation
layer of the OSI model and its function is to
accept requests from applications and
determine whether network access is needed
Software Components of Networking
• Another process used by a NOS is a
designator
• This works in coordination with the redirector
and is associated with drive mapping
• The client /server style is sometimes referred
to as request/reply architecture
• Many request/reply architectures are now
being replaced by event-driven,
publish/subscribe architectures to achieve
real item data delivery
Installing a Network Operating
System
• The installation of a NOS is a bit different
than the installation of a desktop operating
system
• You will configure network services that
determine the framework for the rest of the
network and clients
• Before the server operating system can be
installed, there are some decisions to make
about how the computer will interact on the
network
Installing a Network Operating
System
• Here are some additional
considerations for a server:
– Function of the server
– File systems to be used
– Naming convention to be used
– Other operating systems and applications
– How data will be stored and protected
– Hardware compatibility
Installing a Network Operating
System
• Here are come of the most common
server uses:
– Logon server
– Network services server
– Application, File or Print server
– Web server
– FTP or News/Usenet (NNTP) server
– E-mail server
Installing a Network Operating
System
• After you choose the server type, you must
decide on a file system
• File systems are used to describe the
operating system’s method of organizing,
managing and accessing files through logical
structuring on the hard drive
• File systems interact with the operating
system to be sure that the operating system
can find files that are requested on the hard
disk
Installing a Network Operating
System
• The most common file systems are:
– FAT
– HPFS
– NTFS
• FAT stands for File Allocation Table
• It is simple, reliable, and uses little storage
• Virtual FAT (VFAT) is an enhanced version of
the FAT file system
Installing a Network Operating
System
• High-Performance File System (HPFS) was
designed for the OS/2 operating system to
allow for greater access to larger hard drives
• New Technology File System (NTFS) was
developed expressly for versions of Windows
NT and Windows 2000
• NTFS is required to provide full security for a
Windows file server, and to support
Macintosh datasets
Installing a Network Operating
System
• A naming convention is a process by which
names are created for the workstations and
servers on the network
• It is important to incorporate a scheme for
user accounts, computers, directories,
network shares, printers, and servers so
there is uniformity and logical structure
• They should be descriptive enough to be able
to locate devices quickly, yet not have silly
names
Installing a Network Operating
System
• Determine how data will be stored and
protected
• RAID organizes multiple disks into a
large, high performance logical disk
• There are many types of RAID:
– RAID Level 0
– RAID Level 1
– RAID Level 2
Installing a Network Operating
System
• There are many types of RAID:
– RAID Level 3
– RAID Level 4
– RAID Level 5
– RAID Level 6
– RAID Level 10
• Not all operating systems support all
versions of RAID
Installing a Network Operating
System
• Microsoft publishes what' s called a Hardware
Compatibility List (HCL) which details
compatible hardware for their operating
systems
• Each operating system has minimum
hardware requirements
• Although all NOSs have different installation
steps, the basic process is quite similar
Installing a Network Operating
System
• Most NOSs are installed from a CD-ROM, but
some can be installed over the network if you
have a shared directory and a network boot
disk
• There are setup logs created when a NOS is
installed that can tell what happened to cause
the install to fail
• The cleanup procedure attempts to delete
items that were partially installed or left in an
incomplete state
Installing a Network Operating
System
• After the installation, the server needs to be
configured for:
– DHCP scope(s)
– WINS
– DNS zones
• Once the operating system is installed and
configured it must be kept up to date
• A service pack is an update to an existing
release
Understanding Basic Network
Services
• As the network configuration changes,
the role of the server may change
• Most NOSs have some type of
administrative tool for removing or
adding services
• Often services depend on each other
and stopping one can have a
detrimental effect on others
Understanding Basic Network
Services
• Binding is the process of linking network
components on different levels to enable
communication between the components
• Bindings are links that enable communication
between network adapter card drivers,
protocols, and services
• Bindings establish a logical link between the
upper protocols and lower protocols on the
NIC to provide interoperability
Understanding Basic Network
Services
• The number of protocols run and the
order of the bindings on the client side
can impact network performance
• The more protocols installed, the more
network traffic
• The most frequently used protocol
service or adapter should be bound first
Understanding Basic Network
Services
• With network printing, there are different
operating systems, printer languages, and
various user or department requirements to
meet
• There are three ways a printer can be
networked:
– Connect via serial/parallel to a server
– Connect via serial/parallel to a remote print
server
– Connect via an internal NIC
Understanding Basic Network
Services
• Some factors to be considered when
choosing a strategy for network printing:
– Determine the connection speed
– Check the amount of RAM in the printer
– Be sure you have the proper amount of
RAM
– It might be better to deploy several smaller
printers rather than one large printer
– Make sure that the printer, print server, and
users are close to each other, if possible
Understanding Basic Network
Services
• The directory service is a database of
service names and service addresses
• Different operating systems have
different techniques for doing this
• To ensure the directory service is not
dependent on one computer, the
directory service is often replicated or
mirrored
Understanding Basic Network
Services
• Here is a summary of the features of
directory services:
– A network service that identifies all
resources on a network and makes them
accessible to users and applications
– Stores collection of information about
objects that are name related
– Makes it easier to locate and manage
network resources
Understanding Basic Network
Services
• Two standards for using directory
services over large networks such as
the Internet have been developed:
– X.500 directory service
– Lightweight Directory Access Protocol
(LDAP)
• LDAP is now incorporated in most
vendor releases of Linux
Understanding Basic Network
Services
• Novell NetWare Directory Services (NDS) is
an object-oriented implementation of directory
services that allows sophisticated naming
schemes and databases
• The NDS architecture provides access to all
network resources regardless of where the
resources are physically located