Network Operating Systems : Tasks and Examples Instructor: Dr. Najla Al-Nabhan

Overview  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. 2

Major Tools of NOS 1. 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 2. Enabling and managing access to files on remote systems, and determining who can access what—and who can't 3. 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) 3

Major Tools of NOS 3. Providing routing services, including support for major networking protocols, so that the operating system knows what data to send where 4. Monitoring the system and security, so as to provide proper security against viruses, hackers, and data corruption. 5. 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. 4

Networking Operating Systems (NOS)  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.  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. 5

Tasks of NOS  There are several different Network Operating Systems, each with its own set of features and protocols.  In order to transmit signals across a network, it is necessary for the computer to communicate with its modem or Network Interface Card.  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. 6

Tasks of NOS  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. 7

Tasks of NOS  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. 8

Terminologies  Driver—Also referred to as a device driver. Software that allows communication between the computer and an input/output port or external device.  For example, a driver allows a network operating system to communicate with the Network Interface Card.  · 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. 9

Terminologies  ·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. 10

Terminologies  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. 11

Types of NOSs  There are several different Network Operating Systems, each with its own set of features and protocols.  Sharing of network resources can be peer-to-peer or client/server.  Which NOS is the best is dependent on the end goal of the network. 12

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. 13

Peer-to-Peer NOSs  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.  Examples:  AppleShare used for networking connecting Apple products.  Windows for Workgroups used for networking peer-to-peer windows computers. Advantages  Ease of setup  Less hardware needed, no server needs to be purchased. Disadvantages  No central location for storage.  Lack of security that a client/server type offers.

Client/Server Networks  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. 15

Windows for Workgroups/Windows 95  Windows for Workgroups, introduced in the early 90s  Windows 95, introduced in 1995  They are both considered peer-to-peer networking systems and do not have the capabilities of true internetworking operating systems.  They are, however, inexpensive and more than adequate for small workgroups wanting to share resources, use , and connect to the Internet. 16

Client/Server NOSs  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  Examples:  Novell NetWare  Windows Server  Banyan VINES  Advantages  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  Cost of buying and running a server are high.  Dependence on a central location for operation.  Requires regular maintenance and updates.

Routers NOSs  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:  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  next lecture 20