chapter 11 network operations

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


• 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


• 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


• 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


• Some of the commonly available network operating systems include:– Linux– Novell NetWare– SunOS/Solaris – FreeBSD – Unix– Windows


• 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


• 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


• 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


• 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


• 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


• 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


• 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


• 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


• 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


• The advantages of a client/server network include: – Centralization – Interoperability – Scalability – Flexibility – Expense


• The advantages of a client/server network include:– Dependence – Administration

• The client NOS makes network resources look to the user like they are local


• 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


• Some of the advantages and disadvantages of a peer-to-peer network are:– Less initial expense – Setup – Decentralization – Security – Performance


• 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


• 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


• 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


• 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


• 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


• 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


• 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


• 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


• 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


• 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


• 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


• 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


• 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


• 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


• 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


• 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


• 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


• 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


• 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


• 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


• 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

chapter 11 network operations

Documents

basic network services

network file system

popular commercial network

standalone operating

networking hardware

networked computers

multitasking multitasking

systems noss