NETWORKING ESSENTIALS

PREPARED BY RADHAKRISHNA K 1

Models of network

There are three types of network models

1. Centralized Computing 2. Work Group (peer-to-peer) 3. Domain (Client-Server)

Centralized Computing:

It is the oldest model of networking based on the idea of having one very large and powerful central computer, to which a number of computer terminals are directly connected. In the early days of computing, this central computer would invariably have been a mainframe computer (often called the host computer). This arrangement allowed many users to access the resources of the "host" mainframe computer simultaneously

Workgroup (Peer to peer):

A workgroup is a collection of computers on a local area network (LAN) that share common resources and responsibilities. You simply use the same Workgroup for all the computers and a unique name for each computer. Being a peer-to-peer (P2P) network design all computers acts as a client because there is no centralized server. The user on each computer determines which data on that computer is shared on the network. Security is also managed by the user of the devices. The Microsoft Windows family of operating systems supports assigning of computers to named workgroups. Macintosh networks offer a similar capability through the use of AppleTalk zones. The Open Source software package Samba allows UNIX and Linux systems to join existing Windows workgroups. Criteria for selecting peer to peer

1. Where 10 to 15 or fewer users will be sharing resources. 2. No server is available. 3. Nobody has the time or knowledge to act as a network administrator. 4. There is little or no concerns about security (security in data processing is the ability to protect

data from unauthorized access or, theft or damage) 5. The organization and the network will experience only limited growth within the foreseeable

future. Advantages of using peer to peer

They are easy to configure

Computers communicate easily.

They dont require additional server hardware or software

Users can manage their own resources.

They dont require a network administrator

They reduce total cost of network setup. Disadvantages of using peer to peer

1. They provide a limited number of connections for shared resources. 2. Computers with shared resources suffer from sluggish performance. 3. They dont allow for central management 4. Users are responsible for managing resources. These resources include data in shared

directories, printers, fax cards, and so on. 5. They offer very poor security.

NETWORKING ESSENTIALS

PREPARED BY RADHAKRISHNA K 2

Domain (Client/Server Model)

It is the most common type of network architecture today that provides centralized data storage, security. In client-server model one or more computers work as servers and other computers work as clients. A client is a machine, typically a personal computer (or mobile, desktop or laptop) that is equipped with network software applications. These applications are designed to request and receive data over the span of the network. The server computer controls the whole network, this enables server to keep profile of users, data, and software etc completely in tacked and organized. A server is a storehouse of files, folders, databases and even more complicated applications. A server is more powerful than a client and can support and process the requests of a large number of clients. Operating systems of servers are different from that of clients. Client Operating systems: Windows 95, 98, Me, 2000, XP, Vista, 7 Server Operating Systems: Windows NT, server2000, 2003, 2008 Disadvantages

Cost: - More expensive in terms of hardware and network operating system.

Complexity: - Experienced system administrators are required to manage the systems.

Dependence: - When server goes down, operations will cease across the network. Advantages

1. They are best suited for 10 or more users. 2. Security: - All major server based systems provides sophisticated security. 3. Administration: - Servers are centralized making them easier to manage. 4. Stability: - Server based systems are designed to support a wide range of organization sizes.

Additional servers are added to increase capacity. 5. Client server networks offer centralized backup where data can be stored in one server. 6. Flexibility - New technology can be easily integrated into the system. 7. Accessibility - Server can be accessed remotely and across multiple platforms.

A Windows domain is a logical group of computers running versions of the Microsoft Windows operating system that share a central directory database. This central database known as Active Directory (starting with Windows 2000) contains the user accounts and security information for the resources in that domain. Each person who uses computers within a domain receives his or her own unique account, or user name. This account can then be assigned access to resources within the domain. In a domain, the directory resides on computers that are configured as "domain controllers." A domain controller is a server that manages all security-related aspects between user and domain interactions, centralizing security and administration.

NETWORKING ESSENTIALS

PREPARED BY RADHAKRISHNA K 3

A domain does not refer to a single location or specific type of network configuration. The computers in a domain can share physical proximity on a small LAN or they can be located in different parts of the world. As long as they can communicate, their physical position is irrelevant.

Networking Standards:

A network standard is in short a reference model to make sure products of different vendors can work together in a network; The International Organization for Standardization (ISO) lays out those standards. A network protocol is a set of rule, which govern communication between two or more devices or computer; or, a set of rule and regulation for the communication between devices within a network. For example in order for you to be able to internet you need to have the 'tcp/ip'-protocol enabled. In short, a network standard helps vendors to create products that can all work together; a network protocol allows different network devices to communicate with each other. There are a lot of different network standards that the majority of computers use. There are standards for both physical hardware and for signaling. For example, IEEE 802.11g is a wireless networking standard. It includes specifications for the type of radio that is used, how strong the signal can be amplified, a standard set of encryption schemes, etc. Another standard is Ethernet, also known as IEEE 802.3. This is a standard for hardwired networks. When people talk about Cat 5 cable, this is usually what they mean. It defines what types of wiring can be used, transmission power requirements, connector styles, etc. There are also protocols. TCP/IP is basically the protocol that runs the internet and most LANs that exist today. When people talk about IP addresses, subnet masks, default gateways, etc. those usually pertain to this. Note that TCP/IP is a protocol that is used in conjunction with things like 802.11g or Ethernet. Baseband:

Baseband systems use digital signaling over a single frequency. Signals flow in the form of discrete pulses of electricity or light. With baseband transmission, the entire communication channel capacity is used to transmit a single data signal. The digital signal uses the complete bandwidth of the cable, which constitutes a single channel. A cable's total bandwidth is the difference between the highest and lowest frequencies that are carried over that cable. Each device on a baseband network transmits bidirectional, and some can transmit and receive at the same time.

NETWORKING ESSENTIALS

PREPARED BY RADHAKRISHNA K 4

Bidirectional Digital Wave As the signal travels along the network cable, it gradually decreases in strength and can become distorted. If the cable length is too long, the result is a signal that is weak or distorted. The received signal may be unrecognizable or misinterpreted. As a safeguard, baseband systems sometimes use repeaters to receive an incoming signal and retransmit it at its original strength and definition to increase the practical length of a cable. It is the Digital communication technology in which the entire bandwidth of a medium such as a wire, cable, or channel, is used to transmit a single signal. Therefore, only one communication channel is available at any given time. Baseband is cheaper and simpler technology than broadband, and is employed in most types of local area networks such as Ethernet. Broad Band:

Broadband systems use analog signaling and a range of frequencies. With analog transmission, the signals are continuous and no discrete. Signals flow across the physical medium in the form of electromagnetic or optical waves. With broadband transmission, signal flow is unidirectional.

Unidirectional Analog Wave

If sufficient total bandwidth is available, multiple analog transmission systems such as cable television and network transmissions can be supported simultaneously on the same cable. Each transmission system is allocated a part of the total bandwidth. All devices associated with a given transmission system, such as all computers using a LAN cable, must then be tuned so that they use only the frequencies that are within the allocated range. While baseband systems use repeaters, broadband systems use amplifiers to regenerate analog signals at their original strength. Because broadband transmission signal flow is unidirectional, there must be two paths for data flow in or