WHAT IS IP ADRESS

An identifier for a computer or device on a TCP/IP network. Networks using the TCP/IP protocol route messages based on the IP address of the destination. The format of an IP address is a 32-bit numeric address written as four numbers separated by periods. Each number can be zero to 255. For example, 1.160.10.240 could be an IP address.

Within an isolated network, you can assign IP addresses at random as long as each one is unique. However, connecting a private network to the Internetrequires using registered IP addresses (called Internet addresses) to avoid duplicates.

The four numbers in an IP address are used in different ways to identify a particular network and a host on that network. Four regional Internet registries -- ARIN, RIPE NCC, LACNIC and APNIC -- assign Internet addresses from the following three classes.

Class A - supports 16 million hosts on each of 126 networks

Class B - supports 65,000 hosts on each of 16,000 networks

Class C - supports 254 hosts on each of 2 million networks

The number of unassigned Internet addresses is running out, so a new classless scheme called CIDR is gradually replacing the system based on classes A, B, and C and is tied to adoption of IPv6.

Also see Understanding IP Addressing in the Did You Know . . .? section of Webopedia.

 

What type of network do I need? How will WAN optimization help my network? How do I deploy Wireless LAN?

What are Network Topologies? IP address What wireless networking standard do I use?

How do I secure my wireless network? What appliances will secure my network? How Do I Optimize My Wireless

What is ISP??

Short for Internet Service Provider, it refers to a company that provides Internet services, including personal and business access to the Internet. For a monthly fee, the service provider usually provides a software package,username, password and access phone number. Equipped with a modem, you can then log on to the Internet and browse the World Wide Web andUSENET, and send and receive e-mail. For broadband access you typically receive the broadband modem hardware or pay a monthly fee for this equipment that is added to your ISP account billing.

In addition to serving individuals, ISPs also serve large companies, providing a direct connection from the company's networks to the Internet. ISPs themselves are connected to one another through Network Access Points (NAPs). ISPs may also be called IAPs (Internet Access Providers).

HTTP (Hypertext Transfer Protocol)

HTTP (Hypertext Transfer Protocol) is the set of rules for transferring files (text, graphic images, sound, video, and other multimedia files) on the World Wide Web. As soon as a Web user opens their Web browser, the user is indirectly making use of HTTP. HTTP is an application protocol that runs on top of the TCP/IP suite of protocols (the foundation protocols for the Internet).

HTTP concepts include (as the Hypertext part of the name implies) the idea that files can contain references to other files whose selection will elicit additional transfer requests. AnyWeb server machine contains, in addition to the Web page files it can serve, an HTTPdaemon, a program that is designed to wait for HTTP requests and handle them when they arrive. Your Web browser is an HTTP client, sending requests to server machines. When the browser user enters file requests by either "opening" a Web file (typing in a Uniform Resource Locator or URL) or clicking on a hypertext link, the browser builds an HTTP request and sends it to the Internet Protocol address (IP address) indicated by the URL. The HTTP daemon in the destination server machine receives the request and sends back the requested file or files associated with the request. (A Web page often consists of more than one file.)

The latest version of HTTP is HTTP 1.1.

What is terrestrial microwave technology?

Terrestrial microwave technologies share with satellite microwave technologies many of the scientific and technical improvements used to accomplish microwave transmissions. They are different in that satellite microwave technolgies seek to neutralize the effects of the atmosphere in the microwave transmissions. On the other hand, terrestrial micowave technologies seek the aid of atmospheric effects on microwaves to extend the range limitations imposed by the Earth's curvature. Examples of these terrestrial technologies include those used to exploit troposcattering and meteor-burst in microwave communications--not used at all in satellites.

What is Unbound or Unguided media? 

UNBOUNDED / UN GUIDED MEDIA

Unbounded / Unguided media or wireless media doesn't use any physical connectors between the two devices communicating. Usually the transmission is send through the atmosphere but sometime it can be just across the rule. Wireless media is used when a physical obstruction or distance blocks are used with normal cable media. The three types of wireless media are:

• RADIO WAVES
• MICRO WAVES
• INFRARED WAVES

1. RADIO WAVES:-

It has frequency between 10 K Hz to1 G Hz. Radio waves has the following types.

• Short waves
• VHF (Very High Frequency)
• UHF (Ultra High Frequency)

SHORT WAVES:-

There are different types of antennas used for radio waves. Radio waves transmission can be divided into following categories.

• LOW POWER, SINGLE FREQUENCY.
• HIGH POWER, SINGLE FREQUENCY

1. LOW POWER , SINGLE FREQUENCY:-

As the name shows this system transmits from one frequency and has low power out. The normal operating ranges on these devices are 20 to 25 meter.

CHARACTERISTICS LOW POWER , SINGLE FREQUENCY:-

• Low cost
• Simple installation with pre-configured
• 1 M bps to 10 M bps capacity
• High attenuation
• Low immunity to EMI

2. HIGH POWER, SINGLE FREQUENCY:-

This is similar to low power single frequency. These devices can communicate over greater distances.

CHARACTERISTICS HIGH POWER, SINGLE FREQUENCY:-

• Moderate cost
• Easier to install than low power single frequency
• 1 Mbps to 10 Mbps of capacity
• Low attenuation for long distances
• Low immunity to EMI

Infrared

Infrared frequencies are just below visible light. These high frequencies allow high sped data transmission. This technology is similar to the use of a remote control for a TV. Infrared transmission can be affected by objects obstructing sender or receiver. These transmissions fall into two categories.

1. Point to point
2. Broadcast

(i) Point to Point: - Point to point infrared transmission signal directly between two systems. Many lap top system use point to pint transmission. These systems require direct alignment between many devices.

Characteristics of Point to point:-

• Wide range of cost
• Moderately easy installation.
• 100 k bps to 16 Mb of capacity.
• Variable attenuation.
• High immunity to EMI

(i) Broad Cast: - These infrared transmission use sprayed signal, one broad cast in all directions instead of direct beam. This help to reduce the problems of proper alignment and abstraction. It also allows multiple receiver of signal

Characteristics of Broad Cast:-

• In expensive.
• Single installation.
• 1M bps capacity.
• Variable attenuation.

radio frequency (RF, rf, orr.f.)

Radio frequency (abbreviated RF, rf, orr.f.) is a term that refers to alternating current (AC) havingcharacteristics such that, if the current is input to an antenna, an electromagnetic (EM) field is generated suitable for wireless broadcastingand/or communications. These frequencies cover asignificant portion of the electromagnetic radiation spectrum, extending from nine kilohertz (9 kHz),the lowest allocated wireless communications frequency (it's within the range of human hearing), to thousands of gigahertz(GHz).

When an RF current is supplied to an antenna, itgives rise to an electromagneticfield that propagates through space. This field is sometimescalled an RF field; in less technical jargon it is a "radiowave." Any RF field has a wavelength that is inverselyproportional to the frequency. In the atmosphere or in outerspace, if f is the frequency in megahertz and sis the wavelength in meters, then

s = 300/f

The frequencyof an RF signal is inversely proportional to the wavelengthof the EM field to which it corresponds. At 9 kHz, the free-spacewavelength is approximately 33 kilometers (km) or 21 miles (mi). At the highestradio frequencies, the EM wavelengths measure approximately one millimeter (1 mm). As the frequency isincreased beyond that of the RF spectrum, EM energy takes the form ofinfrared (IR), visible, ultraviolet (UV), X rays, and gamma rays.

Many types of wireless devices makeuse of RF fields. Cordless and cellular telephone, radio andtelevision broadcast stations, satellite communications systems,and two-way radio services all operate in the RF spectrum. Somewireless devices operate at IR or visible-light frequencies,whose electromagnetic wavelengths are shorter than those of RFfields. Examples include most television-set remote-controlboxes, some cordless computer keyboards and mice, and a fewwireless hi-fi stereo headsets.

The RF spectrum is divided into several ranges, orbands. With theexception of the lowest-frequency segment, each band represents an increaseoffrequencycorresponding to an order of magnitude (power of 10). The tabledepictsthe eightbands in the RF spectrum, showing frequency and bandwidth ranges. TheSHF and EHFbands are often referred to as themicrowave spectrum.

Wi-Fi (wireless fidelity)

Wi-Fi (short for "wireless fidelity") is a term for certain types of wireless local area network (WLAN) that use specifications in the 802.11 family. The term Wi-Fi was created by an organization called the Wi-Fi Alliance, which oversees tests that certify product interoperability. A product that passes the alliance tests is given the label "Wi-Fi certified" (a registered trademark).

Originally, Wi-Fi certification was applicable only to products using the 802.11b standard. Today, Wi-Fi can apply to products that use any 802.11 standard. The 802.11 specifications are part of an evolving set of wireless network standards known as the 802.11 family. The particular specification under which a Wi-Fi network operates is called the "flavor" of the network. Wi-Fi has gained acceptance in many businesses, agencies, schools, and homes as an alternative to a wired LAN. Many airports, hotels, and fast-food facilities offer public access to Wi-Fi networks. These locations are known as hot spots. Many charge a daily or hourly rate for access, but some are free. An interconnected area of hot spots and networkaccess points is known as a hot zone.

Unless adequately protected, a Wi-Fi network can be susceptible to access by unauthorized users who use the access as a free Internet connection. The activity of locating and exploiting security-exposed wireless LANs is called war driving. An identifying iconography, called war chalking, has evolved. Any entity that has a wireless LAN should use security safeguards such as the Wired Equivalent Privacy (WEP) encryption standard, the more recent Wi-Fi Protected Access (WPA), Internet Protocol Security (IPsec), or a virtual private network (VPN). 

CABLE

LAN Technology  Cabling
A wireless LAN or WLAN is a wireless local area network, which is the linking of two or more computers without using wires. LAN utilizes spread-spectrum based on radio waves to enable communication between devices in a limited area, also known as the basic service set.

Types Of Cables

•  Unshielded Twiested Pair (UTP) cable  

•   Shielded Twisted Pair (STP) cable 

•  Coaxial Cable 

•  Fiber Optic Cable

•  Wireless LANs

Unshielded Twisted Pair (UTP) cable

 



 The standard connector for unshielded twisted pair cabling is an RJ-45 connector

 










RJ stands for REGISTERED JACK, implying that the connector follows a standard borrowed from the telephone industry. This standard designates which wire goes with each pin inside the connector.


Shielded Twisted Pair (STP) cable

STP is to help provide a more reliable data communication, suitable for environments with electrical interference and consists of two individuals wires wrapped in a foil shielding.
  

Coaxial cable

 







The most common type is called barrel connector because of its shape. Coaxial connectors are familiar from cable TV and VCR hook-ups, which employ both threaded and slip-on styles.



Fibre Optics

The most common connector used with fibre optic cable is an ST connector. It is barrel shaped, similar to a BNC connector.


 Wireless

Wireless telecommunications is the transfer of information between two or more points that are not physically connected.


For Your Addition Notes:


UTP, STP and Coaxial Cable used current while Fiber Optic and Wireless used light.

NETWORK TOPOLOGY

Network topology also called network structures. It is the study of the arrangement or mapping of the elements (links,nodes) of a network, especially the physical and logical level.  The four main type of network topology are bus, star, ring and hybrid. 

A PHYSICAL TOPOLOGY

It is any given node in the LAN will have one or more links. There are some examples of physical topology:

• Ethernet 
• Local Talk

A LOGICAL TOPOLOGY

The mapping of the data flow of the data between the nodes in the network determines the logical topology of the network.

Linear Bus

A linear bus topology consists of a main run of cable with a terminator at each end and continuous length of cable that connects two or more devise together. A linear bus also called a backbone network. Only one computer can transfer information at a time. When a computers sends information, the information move s through the entire length of the cable. The destination computer must retrieve the information from the cable.

• ADVANTAGE

1. Easy to connect a computer or peripheral to a linear bus
2. Requires less cable length than a star topology.
3. Often used to connect a few computers located in a small area.

• DISADVANTAGE

1. Terminators are required at both ends of the backbone
2. A faulty cable or workstation will take the entire LAN.
3. The other computers on the network cannot exchange information while the cable is broken.

STAR TOPOLOGY

Is designed with each node (file server,workstation) connected directly to a central network HUB or concentrator. Data on a star topology passes through the HUB before continuing to its destination. The HUB manages and controls all function of the network.

• ADVANTAGE

1. Easy to install and wire
2. Easy to add new workstations
3. Centralized control

• DISADVANTAGE

1. Requires more cable length than a linear topology
2. If the HUB fails ,nodes attached are disabled
3. Large amount of cable are also used in star topology.

RING TOPOLOGY

A ring topology consists of individual computers connected to a single length of cable arranged in a ring. The information on the ring network travels in one direction only. When computers transfer information it send the information to the computer lactated next to it.

• ADVANTAGE

1. Great for small networks as it easy to install and the cost is usually low.
2. The Media Access Unit (MAU) can also be used to help prevent network shutdown.
3. A break in rings occurs, all computer before break will be able to exchange information.

• DISADVANTAGE

1. Expending a ring network may be difficult that expanding other type of networks.
2. Ring networks can be slightly more expensive to set up the other types pf networks.

HYBRID NETWORK TOPOLOGY

A network structures used a mixture of many different kings of network structures. A hybrid network structures such as ring, star. and bus network in one large network. The bus, ring, star and hybrid, structures all can be used with a centralization network layout.

LAST BUT NOT LEAST :

1. NIC is a network interface controller (also known as a network interface card, network adapter, LAN adapter and by similar terms) is a computer hardware component that connects a computer to a computer network.
2. NOS is a networking operating system (NOS) the software that runs on a server and enables the server to manage data, users, groups, security, applications, and other networking functions.
3. An Ethernet hub or concentrator is a device for connecting multiple twisted pair or fibre optic Ethernetdevices together, making them act as a single segment.
4. LocalTalk is a particular implementation of the physical layer of the AppleTalk networking system from Apple Computer. LocalTalk specifies a system of shielded twisted pair cabling, plugged into self-terminating transceivers.
5. A gateway is a node that allows you to gain entrance into a network and vice versa. On the Internet the node which is the stopping point can be a gateway or a host node. A computer that controls the traffic your network or your ISP (Internet Service Provider) receives is a node. In most homes a gateway is the device provided by the Internet Service Provider that connects users to the internet.
6. In a telecommunications network, a switch is a device that channels incoming data from any of multiple input ports to the specific output port that will take the data toward its intended destination.
7. A repeater is an electronic device that receives a signal and retransmits it at a higher level or higher power, or onto the other side of an obstruction, so that the signal can cover longer distances.

COMPUTER NETWORK

What is meant by computer network??

    Computer Network is connecting a computer with other computers or other devices to enable them to communicate with each other. In addition, communication devices to transmit or to send data from sources to destinations.

NETWORKING COMPONENTS

A network component's functions are not necessarily handled by a specific device. If you browse a networking products catalog, you will find that many products combine several networking components in a device. For example: a router that has a built-in switch, a residential gateway that includes a broadband modem, etc. So, be sure to check the product specification before buying to avoid duplication. You must also check interfaces that are supported by a product. They must be compatible with the ports available in your computers or other devices. A network component's functions may also be performed by a software application. For example, Windows XP provides built-in support for Network Bridging that handle a bridge's functions in a home network with mixed media. There are also built-in or add-on software applications that handle modem, router, or gateway functions. However, the software-only alternative is mostly suitable for small networks.

Do you know what are meant by:

1. Router: A specialized network device that determines the next network point to which it can forward a data packet towards the destination of the packet. Unlike a gateway, it cannot interface different protocols. 
2. AM : Amplitude Modulation is a technique used in electronic communication, most commonly for transmitting information via a radio carrier wave. AM works by varying the strength of the transmitted signal in relation to the information being sent.  
3. FM :   frequency modulation (FM) conveys information over a carrier wave by varying its instantaneous frequency.
4. Bridge: a device that connects multiple network segments along the data link layer. 

Basic Differences Between AM and FM

We need to mention a couple of other things before we leave the discussion of how radio works.  We've talked about AM and FM radio, but we haven't explained the real difference.

In fact, there is a lot of difference — and not just a difference in the station numbers on your radio dial.

The first type of radio service — the one we've been talking about in the last couple of modules — was AM (amplitude modulation) radio.

The term modulation refers to how sound is encoded on a radio wave called a carrier wave; or, more accurately, how the sound affects the carrier wave so that the original sound can later be detected by a radio receiver.

In the top-left of this drawing the RF energy (carrier wave) is not modulated by any sound.  There would be silence on your radio receiver.

In the broadcast process sound is made to affect (modulate) AM carrier wave by changing the amplitude (height) of the wave, as shown on the left.

Unfortunately, this type of modulation is subject to static interference from such things as household appliances — and especially from lightening.

AM also limits the loud-to-soft range of sounds that can be reproduced (called dynamic range) and the high-to-low sound frequency range (called frequency response, to be explained below).  

FM radio, which came along in the 1930s, uses a different approach than AM. It's virtually immune to any type of external interference, it has a greater dynamic range, and it can handle sounds of higher and lower frequencies. This is why music, with its much greater frequency range than the human voice, sounds better on FM radio.

Note on the left that when the carrier wave of FM radio is modulated with sound that the distance between the waves, or the frequency of the carrier wave, changes.  

Thus, AM radio works by changing the amplitude of the carrier wave and FM radio works by changing the frequency of the carrier wave.

TERMINAL AND WORKSTATION

A workstation is a high-end microcomputer designed for technical or scientific applications. Intended primarily to be used by one person at a time, they are commonly connected to a local area network and run multi-user operating systems. The term workstation has also been used to refer to amainframe computer terminal or a PC connected to a network. 

 In computers, a terminal (sometimes qualified as a "dumb" terminal) is an end-use device (usually with display monitor and keyboard) with little or no software of its own that relies on a mainframe or another computer (such as a PC server) for its intelligence.

Transmission Media is to transmit signal or electrical pulse through a medium. There are two types of transmission media such as BOUNDED AND UNBOUNDED.

Example for BOUNDED are:

• Twisted Pair Wire
• Co-Axial
• Fiber Optic Cable

Example for UNBOUNDED are:

• Tv Broadcasting
• Microwave radio
• Infrared signals

NETWORK ELECTRONIC DEVICES

Network devices are components used to connect computers or other electronic devices together so that they can share files or resources like printers or fax machines. Devices used to setup a Local Area Network (LAN) are the most common type of network devices used by the public. A LAN requires a hub, router, cabling or radio technology, network cards, and if online access is desired, a high-speed modem. Happily this is much less complicated than it might sound to someone new to networking.

In a network, one computer is designated as the server, and the others, clients. The server is connected to an external hub, which the clients are also connected to. Now that the computers each have one foot in a common electronic door (the hub), they can use the hub to pass signals back and forth. To direct these signals, the hub contains a device known as a router. The router is the equivalent of an electronic traffic cop that handles data traffic between the computers. Example of network electronic devices are bridges, routers, HUBS, gateway and Front End Processors.

NETWORK OPERATING SYSTEM

 A network operating system (NOS) is a computer operating system system that is designed primarily to support workstation, personal computer, and, in some instances, older terminalthat are connected on a local area network (LAN). Artisoft's LANtastic, Banyan VINES, Novell's NetWare, and Microsoft's LAN Manager are examples of network operating systems. In addition, some multi-purpose operating systems, such as Windows NT and Digital's OpenVMS come with capabilities that enable them to be described as a network operating system.

A network operating system provides printer sharing, common file system and database sharing, application sharing, and the ability to manage a network name directory, security, and other housekeeping aspects of a network.