NETWORK CLASSIFICATION

LAN (LOCAL AREA NETWORK)

·         A LAN connects network devices over a relatively short distance.

·         A networked office building, school, or home usually contains a single LAN, though sometimes one building will contain a few small LANs (perhaps one per room), and occasionally a LAN will span a group of nearby buildings.

·         In TCP/IP networking, a LAN is often but not always implemented as a single IP subnet.

·         In addition to operating in a limited space, LANs are also typically owned, controlled, and managed by a single person or organization.

·         They also tend to use certain connectivity technologies, primarily Ethernet and Token Ring.

WAN (WIDE AREA NETWORK)

·         As the term implies, a WAN spans a large physical distance. The Internet is the largest WAN, spanning the Earth.

·         A WAN is a geographically-dispersed collection of LANs. A network device called a router connects LANs to a WAN. In IP networking, the router maintains both a LAN address and a WAN address.

·         A WAN differs from a LAN in several important ways. Most WANs (like the Internet) are not owned by any one organization but rather exist under collective or distributed ownership and management. WANs tend to use technology like ATM, Frame Relay and X.25 for connectivity over the longer distances.

MAN (METROPOLITAN AREA NETWORK)

·         Network that interconnects users with computer resources in a geographic area or region larger than that covered by even a large local area network (LAN) but smaller than the area covered by a wide area network (WAN). The term is applied to the interconnection of networks in a city into a single larger network (which may then also offer efficient connection to a wide area network). It is also used to mean the interconnection of several local area networks by bridging them with backbone lines. The latter usage is also sometimes referred to as a campus network.

PAN (PERSONAL AREA NETWORK)

·         Computer network organized around an individual person. Personal area networks typically involve a mobile computer, a cell phone and/or a handheld computing device such as a PDA. You can use these networks to transfer files including email and calendar appointments, digital photos and music.

·         Personal area networks can be constructed with cables or wirelessly. USB and FireWire technologies often link together a wired PAN while wireless PANs typically use Bluetooth or sometimes infrared connections. Bluetooth PANs are also called piconets.

·         Personal area networks generally cover a range of less than 10 meters (about 30 feet).

What Email is and How It Works

Email and Postal Mail

• The email message - Instead of using a pen to write a letter on paper, you're using your keyboard to type an email message in an email program on your computer.
• Sending the email - When the email is finished and has been addressed to the recipient's email address, you don't put a stamp on it and post it but press the Send button in the email program. This makes the email message go on its journey.
• Email transport - Like postal services transport letters and parcel, email servers transmit email messages from sender to recipient. Usually, emails are not delivered to the recipient directly, though, but waiting at the "nearest" mail server to be picked up by them.
• Fetching new mail - If you've got new mail in your mailbox, you go and fetch it. Similarly, your email program can check for new email messages at your mail server and download them for you to read.

The benefits and wonders of email include

• Convenience - If a desktop computer, laptop or mobile phone is around, you can type your email message wherever you want, save it for later use and send it at any time without having to worry about envelopes, stamps and tariffs.
• Speed - Emails typically arrive within seconds or minutes — anywhere in the world, something that can be said only about a negligible number of the letters I've sent via postal mail.
• Attachments - You can attach any file on your computer to an email message easily, regardless of its type and, mostly, size. It's as easy to send a long master's thesis around the world as it is to email a spread sheet, a report, pictures, or a saved game of your favorite game.
• Accessibility - Emails can be stored conveniently in your email program. Good programs make it easy to organize, archive and search your emails, so any information contained in an email is always readily accessible.
• Cost - Safe for the fee you pay for accessing the internet, sending and receiving emails is typically free.

Email's Problem

Unfortunately, the last beneficial wonder in particular is also responsible email's big problem: spam — unsolicited emails that are sent in huge numbers and clog mail servers as well as email programs.

With hundreds of these junk mails in your inbox, the occasional good email can be hard to spot. Fortunately, though, sophisticated filters exist that go through your new messages and sort out the unwanted ones automatically.

NETWORK TOPOLOGY

Architecture

·         One of the 2 major type of network architecture

Ø  Peer to peer

      Communications between diplomats of the same rank. In the networking environment, "peer to peer" refers to communications between similar processes running in different computers, or communication between devices that are equal with regard to how they exchange information and control communications.

Ø  Client and server

      Server-powerful computer or process dedicated to managing disk drivers (file server), printer (print server), or network traffic (network servers).

      Clients-PC’s or workstations on which users run applications. Client rely on server for resources such as files, devices and even processing power.

Topology

·         Geometric arrangement of network.

Protocol

·         Command set of rules and signal competence on the network use to communicate.

Network topology

·         Bus wire

·         Star ring

·         Star

·         Tree

Linear bus

Ø  One computer can transfer information at a time.

Ø  Suitable for small area.

Ø  Each end of terminator (device that absorb the signal transmitted on the network cable). The terminator prevent signal from being bounce back a long the cable and cause interference.

Ø  Node (devices-computer, printer, and others).

Star

Ø  Individual connected to a center point of the network (hub/concentrator).

Ø  All information passes through hub.

Ø  Cable length between computers and hub should be less than 100 meter.

Ø  Hub commonly connects for 8 and 16 computers.

Ø  Office or large buildings of each floor of the building have to have its own hub.

Ø  In the middle of the star should have a hub.

Ø  Information going to the hub first.

Ø  Hub is functioning as a repeater.

Star-wired

Ø  Individual computer connected at each in a single ring cable.

Ø  Information travel in one direction only.

Ø  Next computer that will not address will pass to the next, continue pass until it reach its destinations.

Ø  There is no beginning or end.

Tree

Ø  Combines characteristics of linear bus and star topology.

Ø  Tree topologies integrate multiple star topologies together onto a bus. In its simplest form, only hub devices connect directly to the tree bus, and each hub functions as the "root" of a tree of devices. This bus/star hybrid approach supports future expandability of the network much better than a bus (limited in the number of devices due to the broadcast traffic it generates) or a star (limited by the number of hub connection points) alone.

How WiFi Works

Wireless Technology

Wireless Networking Hardware

network cables, for example, between two rooms or two buildings. However,
recent advances in wireless networking technology make wireless networking
practical and affordable. New wireless standards have facilitated the
development of wireless products with good performance and the ability to
integrate easily into a wired Ethernet network.
The Ethernet standard for wireless networking is the IEEE 802.11b
wireless standard. The 802.11b standard supports wireless connections at
speeds up to 11 Mps, comparable to 10 Mbps wired Ethernet. Wireless
industry leaders formed the Wireless Ethernet Compatibility Alliance
(WECA) to certify cross-vendor compatibility with the 802.11b standard.
These products display the WECA "Wireless Fidelity" (Wi-Fi†) logo.


Suppose you want to network a few computers together in a small area
where it would be expensive to have network cabling installed in an existing building. Or perhaps you just have a desktop computer and a notebook
computer at home and you would like to be able to roam the house with the
notebook computer and perhaps even browse the Web from the hammock in
the back yard. Wireless Ethernet makes all this possible. You can install
wireless adapters in each computer and form a wireless network.

Building a Simple Network

Sharing an Internet Connection
If you already have access to the Internet from one computer on your
network, you can share that Internet connection with other computers on the
network. Then all the computers on your network can browse the Web at the
same time, using this single Internet connection.
Networking Components
To network computers together, you need to install networking hardware and
software. Every network includes these three components:
􀂄 The computers that are connected together. Computers and similar
devices are called nodes when connected to a network.
􀂄 The networking hardware that connects the computers together,
including hardware installed in your computer, network cables, and
devices that connect all the cables together.
􀂄 Networking software that runs on each computer and enables it to
communicate with other computers on the network.
Networking Hardware
Here is the networking hardware you need to set up a small network:
􀂄 Network adapter cards: expansion cards that provide the physical
connection between each computer and the network. The card installs
into a slot on your computer, just like a sound card or modem card.
Some newer computers have a network adapter already built into the
system. Laptop computers often use a card that slides into a PC card
slot.
Chapter 1: Introduction to Networking 5
Figure 1.5 Network Adapter Card
􀂄 Network hub: the central connection point for network cables that
connect to computers or other devices on a network. The hub has
several network cable jacks or ports that you use to connect network
cables to computers. The hub contains circuitry that enables each
computer to communicate with any other computer connected to
the hub.
Figure 1.6 Network Hub
􀂄 Network cables: special, unshielded twisted-pair (UTP) cables used
to connect each computer to the hub. The cable you need is Category
5 UTP cable with a square plastic RJ-45 connector on each end.
6 Building a Simple Network
Figure 1.7 Network Cable with RJ-45 Connector
All the networking hardware described here is known as Ethernet.
Ethernet is the industry-wide standard for computer networks. Standard
Ethernet networks transmit data at 10 million bits per second (Mbps).
A newer Ethernet standard, called Fast Ethernet, transmits data at 100 Mbps.
Computer networks often contain a mixture of 10 Mbps and 100 Mbps
devices.