NETWORKING

WHAT IS COMPUTER NETWORK??

• Networks are collections of computers, software, and hardware that are all connected to help their users work together. 
• Computer networks fall into two main types: 

1. client/server networks = Uses one or more dedicated machines to share the files, printers, and applications.
2. and peer-to-peer networks= A peer-to-peer network allows any user to share files with any other user and doesn’t require a central, dedicated server.

• The most common networks are Local Area Networks or LANs for short. 
• A LAN connects computers within a single geographical location, such as one office building, office suite, or home. By contrast, Wide Area Networks (WANs) span different cities or even countries, using phone lines or satellite links.
• Networks are often categorized in other ways, too. You can refer to a network by what sort of circuit boards the computers use to link to each other – Ethernet and Token-Ring are the most popular choices. You can also refer to a network by how it packages data for transmission across the cable, with terms such as TCP/IP (Transmission Control Protocol/Internet Protocol) andIPX/SPX (Internet Package eXchnage/Sequenced Package eXchange).

TYPE OF NETWORK :

• Personal Area Network (PAN)
• Local Area Network (LAN)
• Metropolitan Area Network (MAN)
• Wide Area Network (WAN)

# this video are very useful to understanding the type of network communication. I've also understand more about this chapter from this video ;D

Personal Area Network ( PAN )

-A personal area network (PAN) is a computer network used for communication among computerized devices, including telephones and personal digital assistants. 

EXAMPLE:

Bluetooth

Bluetooth uses short-range radio waves over distances up to approximately 10 metres. For example, Bluetooth devices such as a keyboards, pointing devices, audio head sets, printers may connect to Personal digital assistants (PDAs), cell phones, or computers wirelessly.

Infrared Data Association

Infrared Data Association uses infrared light, which has a frequency below the human eye's sensitivity. It is used, for instance, in cell phones, TV remotes and ps3 controllers. Typical WPAN devices that use IrDA include printers, keyboards, and other serial data interfaces.

WiFi

WiFi uses radio waves for connection over distances up to around 91 metres, usually in a local area network (LAN) environment. Wifi can be used to connect local area networks, to connect cellphones to the Internet to download music and other multimedia, to allow PC multimedia content to be stream to the TV (Wireless Multimedia Adapter), and to connect video game consoles to their networks.

# one type of PAN

Local Area Network

LAN stands for Local Area Network (as opposed to WAN, or Wide Area Network), which commonly refers to how a connection to the Internet is made. LANs are used to connect computers that are geographically close together, whether inside a room or inside a building. This allows people to share files and printers, play computer games together and even send music to a stereo system or videos to a television

The Basic LAN

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  The basic type of LAN is connected by Ethernet cables to a router or hub (modern routers usually integrate hubs). A router allows all computers connected to it to access a high-speed modem connected to the router. Each computer has an IP (Internet Protocol) address, but a computer on the other side of the Internet will only see the router's IP address. This, and a router's built-in firewall, creates a safer environment for accessing the Internet. (Firewalls are used to filter out unauthorized access to the network.)

#one type of LAN 

Metropolitan Area Network 

A metropolitan area network (MAN) is a computer network that usually spans a city or a large campus. A MAN usually interconnects a number of local area networks (LANs) using a high-capacity backbone technology, such as fiber-optical links, and provides up-link services to wide area networks (or WAN) and the Internet.

Type of Metropolitan Area Network ( MAN )

Wide Area Network ( WAN )

Definition: A WAN spans a large geographic area, such as a state, province or country. WANs often connect multiple smaller networks, such as local area networks (LANs) or metro area networks (MANs).

TYPE OF WAN 

Networking Guide : Network Components

Besides a physical medium, a network operation needs devices that are designed to handle certain network functions. The devices are often called networking devices or equipment and specifically referred to as network components in this guide. Each network component has a name that is related to its functions. For example, a network adapter works to "adapt" a computer message that is going to be sent to a network, to a format that is defined by the network.

Picture: Networking Hardware

1. Terminal and Workstation
2. Transmission Media
3. Network Electronic Device
4. Software 

1. Terminal and Workstation

what is terminal and workstation in networking?

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Terminal as it relates to a workstation is usually a user interface [keyboard/mouse/video] that has enough stuff to get connected to a main frame/VAX/terminal server. A terminal does minimal processing.

A workstation on the other hand has all the stuff it needs and does all of the processing. It does not need to connect to a server to do its stuff.

example:

#lowest workstation terminal

 # Network terminal

2. Transmission Media

The means through which data is transformed from one place to another is called transmission or communication media. There are two categories of transmission media used in computer communications.

1. BOUNDED MEDIA:

Bounded media are the physical links through which signals are confined to narrow path. These are also called guide media. Bounded media are made up o a external conductor (Usually Copper) bounded by jacket material. Bounded media are great for LABS because they offer high speed, good security and low cast. However, some time they cannot be used due distance communication. Three common types of bounded media are used of the data transmission. These are

• Coaxial Cable
• Twisted Pairs Cable
• Fiber Optics Cable

COAXIAL CABLE:

Coaxial cable is very common & widely used commutation media. For example TV wire is usually coaxial.

CHARACTERISTICS OF COAXIAL CABLE

• Low cost
• Easy to install
• Up to 10Mbps capacity
• Medium immunity form EMI
• Medium of attenuation

ADVANTAGES COAXIAL CABLE

• Inexpensive
• Easy to wire
• Easy to expand
• Moderate level of EMI immunity

DISADVANTAGE COAXIAL CABLE

• Single cable failure can take down an entire network

Twisted Pair Cable

The most popular network cabling is Twisted pair. It is light weight, easy to install, inexpensive and support many different types of network. It also supports the speed of 100 mps.Twisted pair cabling is made of pairs of solid or stranded copper twisted along each other. The twists are done to reduce vulnerably to EMI and cross talk. The number of pairs in the cable depends on the type. The copper core is usually 22-AWG or 24-AWG, as measured on the American wire gauge standard. There are two types of twisted pairs cabling

1. Unshielded twisted pair (UTP)

2. Shielded twisted pair (STP)

1. Unshielded twisted pair (UTP)

      

Characteristics of UTP

•  low cost
• easy to install
• High speed capacity
• High attenuation
• Effective to EMI
• 100 meter limit

Advantages of UTP

• Easy installation
• Capable of high speed for LAN
• Low cost

Disadvantages of UTP

• Short distance due to attenuation

2. Shielded twisted pair (STP)

It is similar to UTP but has a mesh shielding that’s protects it from EMI which allows for higher transmission rate.

Characteristics of STP

• Medium cost
• Easy to install
• Higher capacity than UTP
• Higher attenuation, but same as UTP
• Medium immunity from EMI
• 100 meter limit

Advantages of STP:

• Shielded
• Faster than UTP and coaxial

Disadvantages of STP:

• More expensive than UTP and coaxial
• More difficult installation
• High attenuation rate

Fiber Optics

Fiber optic cable uses electrical signals to transmit data. It uses light. In fiber optic cable light only moves in one direction for two way communication to take place a second connection must be made between the two devices. It is actually two stands of cable. Each stand is responsible for one direction of communication. A laser at one device sends pulse of light through this cable to other device. These pulses translated into “1’s” and “0’s” at the other end.

In the center of fiber cable is a glass stand or core. The light from the laser moves through this glass to the other device around the internal core is a reflective material known as CLADDING. No light escapes the glass core because of this reflective cladding.

Fiber optic cable has bandwidth more than 2 gbps (Gigabytes per Second)

Characteristics Of Fiber Optic Cable:

• Expensive
• Very hard to install
• Capable of extremely high speed
• Extremely low attenuation
• No EMI interference

Advantages Of Fiber Optic Cable:

• Fast
• Low attenuation
• No EMI interference

Disadvantages Fiber Optics:

• Very costly
• Hard to install

3. NETWORK ELECTRONIC DEVICE

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.

HUB

A common connection point for devices in a network. Hubs are commonly used to connect segments of a LAN. A hub contains multiple ports. When apacket arrives at one port, it is copied to the other ports so that all segments of the LAN can see all packets.

A passive hub serves simply as a conduit for the data, enabling it to go from one device (or segment) to another. So-called intelligent hubs include additional features that enables an administrator to monitor the traffic passing through the hub and to configure each port in the hub. Intelligent hubs are also called manageable hubs.

A third type of hub, called a switching hub, actually reads the destination address of each packet and then forwards the packet to the correct port.

ROUTER

Definition: Routers are physical devices that join multiple wired or wireless networks together. Technically, a wired or wireless router is a Layer 3 gateway, meaning that the wired/wireless router connects networks (as gateways do), and that the router operates at the network layer of the OSI model.

WHAT IS BETWEEN HUB AND ROUTER??? ;)

SWITCH

In electronics, a switch is an electrical component that can break an electrical circuit, interrupting the current or diverting it from one conductor to another.




BRIDGE


Definition: A bridge device filters data traffic at a network boundary. Bridges reduce the amount of traffic on a LAN by dividing it into two segments.

Bridges operate at the data link layer (Layer 2) of the OSI model. Bridges inspect incoming traffic and decide whether to forward or discard it. An Ethernet bridge, for example, inspects each incoming Ethernet frame - including the source and destination MAC addresses, and sometimes the frame size - in making individual forwarding decisions.

Bridges serve a similar function as switches, that also operate at Layer 2. Traditional bridges, though, support one network boundary, whereas switches usually offer four or more hardware ports. Switches are sometimes called "multi-port bridges" for this reason.

GATEWAY

Definition: A network gateway is an internetworking system capable of joining together two networks that use different base protocols. A network gateway can be implemented completely in software, completely in hardware, or as a combination of both. Depending on the types of protocols they support, network gateways can operate at any level of the OSI model.

What is gateway & how it works?

Gateways work on all seven OSI layers. The main job of a gateway is to convert protocols among communications networks. A router by itself transfers, accepts and relays packets only across networks using similar protocols. A gateway on the other hand can accept a packet formatted for one protocol (e.g. AppleTalk) and convert it to a packet formatted for another protocol (e.g. TCP/IP) before forwarding it. A gateway can be implemented in hardware, software or both, but they are usually implemented by software installed within a router. A gateway must understand the protocols used by each network linked into the router. Gateways are slower than bridges, switches and (non-gateway) routers.

A gateway is a network point that acts as an entrance to another network. On the Internet, a node or stopping point can be either a gateway node or a host (end-point) node. Both the computers of Internet users and the computers that serve pages to users are host nodes, while the nodes that connect the networks in between are gateways. For example, the computers that control traffic between company networks or the computers used by internet service providers (ISPs) to connect users to the internet are gateway nodes.

# ENJOY WATCHing DIS VIDEO !! ;D

SOFTWARE

A network (=server) operating system (NOS)

– a piece of software that controls a network and its message traffic and queues, controls

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access by multiple users to network resources such as files, and provides for certain administrative functions, including security.

– Installed on the server

client software
– Installed on the PC/cmputers to access the
network and to issue requests to the
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network

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