Transcript Network 1 S02

Network 1
S02
By Dr Ahmad AA Alkhatib
Network Cabling Basics
For networks to work, the computers must have the capability to take the
bits sitting in RAM on one computer and somehow send a copy of those bits
into RAM on the other computer. For the process to work, the computer
typically asks the NIC to send the bits over the cable that is connected to the
NIC. So, the NIC must be connected to some form of transmission medium
over which it can send the bits to the other computer.
Creating a Transmission Medium Using Cables
To send data—bits—to another computer, the computers can use some
physical medium over which electricity can be sent. In this case, the
physical medium is typically a set of copper wires because copper easily
conducts electricity. Because copper wires are brittle, the wires are usually
wrapped in a colored plastic coating to help prevent them from breaking.
The plastic coating also helps provide some electrical insulation.
The term bits per second (bps) often refers to the speed of network
connections. Note that the unit is bits, not bytes. In real life, LANs typically
run at much higher speeds, with a slow LAN transmitting at 10 million bits
per second (megabits per second, or Mbps). The section “Names for the
Rate at Which a Network Sends Data” describes the speeds at which bits
can be sent over a networking cable
Networks Basics(Cont…)
Transmission Control
Protocol/Internet Protocol (TCP/IP)
is a set of protocols or rules
developed to allow cooperating
computers to share resources across a
network.
To enable TCP/IP on the
workstation, it must be configured
using the operating system tools.
Telecommunication Systems
Consider for a moment all the different communications that take place in an
organization. Some communications are face to face, but others use some
type of technology. Think of email, phone calls, text messaging, viewing
pages on the Internet, downloading files. All of these communications make
use of a telecommunications system.
A telecommunications system is a collection of nodes and links to enable
telecommunication. Telecommunication is communication at a distance
using electrical signals or electromagnetic waves.
Examples of telecommunications systems are the telephone network, the
radio broadcasting system, computer networks and the Internet. The nodes
in the system are the devices we use to communicate with, such as a
telephone or a computer.
Components of a Telecommunication System
In its most fundamental forms, a telecommunication system includes a
transmitter to take information and convert it to a signal, a transmission
medium to carry the signal and a receiver to take the signal and convert it
back into usable information. This applies to any communication system,
whether it uses computers or not.
Most modern day telecommunications systems are best described in terms
of a network. This includes the basic elements listed above but also the
infrastructure and controls needed to support the system. There are six
basic components to a telecommunications network.
1.
Input and output devices, also referred to as 'terminals‘ These provide the
starting and stopping points of all communication. A telephone is an
example of a terminal. In computer networks, these devices are commonly
referred to as 'nodes' and consist of computer and peripheral devices.
2. Telecommunication channels, which transmit and receive data This
includes various types of cables and wireless radio frequencies.
3. Telecommunication processors, which provide a number of control and
support functions For example, in many systems, data needs to be
converted from analog to digital and back.
4. Control software, which is responsible for controlling the functionality
and activities of the network
5. Messages represent the actual data that is being transmitted In the case
of a telephone network, the messages would consist of audio as well as
data.
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6. Protocols specify how each type of telecommunication systems handle
the messages For example, GSM and 3G are protocols for mobile phone
communications, and TCP/IP is a protocol for communications over the
Internet.
Different Types of Networks
There are a number of different ways to describe computer networks,
including network size, transmission media, management method and
network topology.
Network types
The transmission media of a computer network describes the material
substances that carry energy waves, which include the data being
transferred. The two main categories are wired connections, which use
physical cables, and wireless connections, which use electromagnetic
waves and do not require a physical medium. The most commonly used
wired connections use twisted-pair cables, coaxial cables and fiber optic
cables. The most commonly used wireless connections use radio waves,
microwaves and infrared waves.
Networks Types
There are several different types of computer networks. Computer networks can be characterized by
their size as well as their purpose.
The size of a network can be expressed by the geographic area they occupy and the number of computers
that are part of the network. Networks can cover anything from a handful of devices within a single room
to millions of devices spread across the entire globe.
Some of the different networks based on size are:
Personal area network, or PAN
Local area network, or LAN
Metropolitan area network, or MAN
Wide area network, or WAN
In terms of purpose, many networks can be considered general purpose,
which means they are used for everything from sending files to a printer to
accessing the Internet. Some types of networks, however, serve a very
particular purpose. Some of the different networks based on their main
purpose are:
Storage area network, or SAN
Enterprise private network, or EPN
Virtual private network, or VPN
Let's look at each of these in a bit more detail.
Personal Area Network
A personal area network, or PAN, is a computer network organized around
an individual person within a single building. This could be inside a small
office or residence. A typical PAN would include one or more computers,
telephones, peripheral devices, video game consoles and other personal
entertainment devices.
If multiple individuals use the same network within a residence, the network
is sometimes referred to as a home area network, or HAN. In a very typical
setup, a residence will have a single wired Internet connection connected to
a modem. This modem then provides both wired and wireless connections
for multiple devices. The network is typically managed from a single
computer but can be accessed from any device.
This type of network provides great flexibility. For example, it allows you to:
Send a document to the printer in the office upstairs while you are sitting on
the couch with your laptop.
Upload the photo from your cell phone to your desktop computer.
Watch movies from an online streaming service to your TV.
If this sounds familiar to you, you likely have a PAN in your house without
having called it by its name.
Networks Types(Cont…)
Local Area Networks (LANs) are designed to :
- Operate within a limited geographical area.
- Allow multi-access to high bandwidth media.
- One single interface for each host (Point to multipoint).
- Control the network privately under local administration
(installation, troubleshooting, developing).
- Provide full-time connectivity to local services.
- Connect Physically adjacent devices.
- All the devices must be owned by the customer.
A local area network, or LAN, consists of a computer network at a single
site, typically an individual office building. A LAN is very useful for sharing
resources, such as data storage and printers. LANs can be built with
relatively inexpensive hardware, such as hubs, network adapters and
Ethernet cables.
The smallest LAN may only use two computers, while larger LANs can
accommodate thousands of computers. A LAN typically relies mostly on
wired connections for increased speed and security, but wireless
connections can also be part of a LAN. High speed and relatively low cost
are the defining characteristics of LANs
LANs are typically used for single sites where people need to share
resources among themselves but not with the rest of the outside world.
Think of an office building where everybody should be able to access files
on a central server or be able to print a document to one or more central
printers. Those tasks should be easy for everybody working in the same
office, but you would not want somebody just walking outside to be able to
send a document to the printer from their cell phone! If a local area network,
or LAN, is entirely wireless, it is referred to as a wireless local area network,
or WLAN.
Networks Types(Cont…)
Wide Area Networks (WANs) are designed to :
- Operate over wide geographical area.
- Allow access over serial interfaces operating at lower speeds.
- Provide full time and part time connectivity.
- Connect devices separated over wide, even global areas.
- There is an fee paid to the provider.
A wide area network, or WAN, occupies a very large area, such as an entire
country or the entire world. A WAN can contain multiple smaller networks,
such as LANs or MANs. The Internet is the best-known example of a public
WAN.
MAN
A metropolitan area network, or MAN, consists of a computer network
across an entire city, college campus or small region. A MAN is larger than a
LAN, which is typically limited to a single building or site. Depending on the
configuration, this type of network can cover an area from several miles to
tens of miles. A MAN is often used to connect several LANs together to form
a bigger network. When this type of network is specifically designed for a
college campus, it is sometimes referred to as a campus area network, or
CAN.
Private Networks
One of the benefits of networks like PAN and LAN is that they can be kept
entirely private by restricting some communications to the connections
within the network. This means that those communications never go over
the Internet.
Networks Types(Cont…)