Sunday, 3 June 2012

Internet Infrastructure -- Last Lecture


Wednesday, 30th May 2012
This was the last lecture for SPPM 1013. We had learned about Internet Infrastructure as our last topic of this subject.
Firstly, I learned that there is a hierarchy of Networks : -
(I.)          from a single computer to LAN
(II.)         from LAN to ISP
(III.)       ISP to WWW
Besides, other things I came across several specific terms which related to Internet. These terms were Internet Protocol (IP), Domain Name System (DNS), Internet Service Provider (SP) and Hyper Text Transfer Protocol (HTTP).
These things are really technical stuff but I always have a curios heart to know more about them.

Internet Protocol  (IP)
IP is the Internet Standard that provides a common layer over dissimilar networks which is used to move packets among host computers and through gateways if necessary.
IP addresses are used to identify computers available through the Internet. They are numeric and commonly used by computers to refer to other computers. An IP address consists of 32 bits, which distribute evenly in 4 octets (each octet consists of 8 bits). The numbers in each octet are ranged from 0-225. There are two forms of IP address : -
(I)            Numeric form – eg. 168.212.226.204
(II)          Binary form – eg. 10101000.11010100.11100010.11001100
 There are two parts in an IP address. The beginning of the IP address indicates the networks that it belongs to whereas the other numbers show the host on that network. All nodes in the same network will begin with the same prefix, the rest of the numbers are representing the specific nodes or hosts. There are 5 classes of networks exist nowadays.
Next, we had learned about Domain Name System (DNS)
DNS reflects the name of the individual or organization associated with that Web site and the different parts of a domain name are separated by a period.
DNS is easier to remember as the identity of a specific website when it is compared to the IP address (no matter numeric or binary address).
Lastly, there were two terms that we were required to find out.
Ø  ISP – Internet Service Provider (ISP) / Internet Access Provider (IAP) is business or other organizations that provide Internet access to others, typically for a fee.
Ø  HTTP – Hyper Text Transfer Protocol (HTTP) is the underlying protocol used by the World Wide Web (WWW). It defines how messages are formatted and transmitted, and what actions Web servers and browsers should take in response to various commands. For instance, when we type URL in the searching bar and clicks ENTER, a HTTP command is then sent to the Web Server in order to reach to the requested web page. HTTP only transfers the contents of web page into browser for viewing.

That’s all from me ^^
 

Sunday, 13 May 2012

Bluetooth + Broadband + Infrared >>> Unbounded Media

Wednesday, 9th May 2012

Bluetooth >>> this is a very familiar word among youngster. We use it whenever we want to transfer media like songs and pictures between mobile phones. 
So, the function of Bluetooth is to connect and exchange information between devices such as mobile phones, laptops, PCs, printers, digital cameras and video game consoles over a secure, globally unlicensed short-range radio frequency. Similarly, we need to know how the data transfer through Bluetooth and what are the devices used in the transfer.

Transfer of Data using Bluetooth

Basically, Bluetooth technology use radio wave to transmit data and it follows the IEEE 802.15 standard. The technology that enables it to transmit data with lesser problems caused by interference is Spread-spectrum Frequency Hopping technology. This technology enables the data transfer occurs on unlicensed 2.4 GHz (Industrial, Scientific and Medical) frequency band that is shared among other devices (microwave ovens, cordless phones, garage door openers, etc. ) and hence, avoiding the interference with other devices.
On the other hand, the speed of the data transmission is the same when there are more than one user using Bluetooth technology to transfer data at the same time. Unlike Wi-Fi, when there are many users using Wi-Fi at the same time, the speed of data transmission is definitely slower. 

Before the client (the sender) transfers a media (data) to the server (other bluetooth enabled devices), the client has to send a request to the server. Then, the server has to receive the data transfer from the client in order to initiate the transfer of data. 


The data transfer through Bluetooth consume only a little amount of energy as compared to cellphone. Bluetooth transfer emit only 1 miliwatt of signal whereas cellphone emit 3 milliwatt. However, one of the advantages of bluetooth transfer is that it can tranmit data although there is barrier like walls.


The Devices Used
In order to connect with other Bluetooth enabled devices, every device no matter the client or the server has to associate with a transceiver microchips, either build in (eg. Bluetooth card) or connect externally (eg. Bluetooth USB Dongle). 
-    
     Devices build-in with transceiver microchips which function as transferring and receiving devices.

OR

-    External Bluetooth device called Bluetooth dongle for those devices that do not have build-in transceiver.

^^ Bluetooth Microchip
^^ Bluetooth Dongle

Drawbacks of Using Bluetooth to Transfer Data
-     Distance covered is limited within 10m
-    Speed of transferring data is slowest (1Mbps) when it compared to Infrared (4Mbps) and Wi-Fi (11Mbps – 54Mbps)

The Future of Bluetooth
Bluetooth technology is expected to stay strong in the future because Windows and Mac OS continue their native support for it. Besides, there are also many emerging features such as Bluetooth in cars; automatic configuration of Piconets; and Quality of Service (QoS) improvements which shows its potential to be used widely in the future.

Broadband
Broadband is a technology that transmits data faster than Bluetooth. Band refers to the bandwidth which means the amount of data that can be sent from one computer to another through a particular connection in a certain amount of time; thus, broadband means that this technology is able to transmit more data and at a higher speed than narrowed frequencies (eg. Bluetooth).
Data transmission using broadband is more effective than Bluetooth because it can carry multiple media such as voice, video or other data at once with different channels. These channels are taking different frequencies or specific time slot to avoid interference occur. Examples of broadband technologies are broadcast television, cable television, microwave, satellite, wireless phones and others. To make it clear, let’s take cable television as an example. Cable television is able to carry 30 or more TV channels just like broadband.     

Infrared
Infrared technology transmits data slower than broadband but faster than Bluetooth. The maximum amount of data that can be carried through infrared is 4Mb. 

To understand the data transfer through infrared, let’s use remote control as an example.
Basically, remote control use a particular wavelength to communicate with the device that it command. When there is an instruction from the remote control, its transmitter sends out infrared light in the form of pulses to the device that is commanded by it. Then, the pulses are translated into binary codes which represent its command. At this moment, the remote control must be placed in front of the commanded device in order to transmit data in the line of sight.  Later on, the commanded device receives these pulses of light and decodes them into binary data, which is understood by the microprocessor inside it. 

That's all from me. Thanks!

Saturday, 5 May 2012

Unbounded Media....(haizzz....abstract....==")


Wednesday, 2nd May 2012

We learned about Unbounded Media today. As I mentioned last week, Unbounded Media is also known as Unguided Media. This means that transmission of data is done without any physical conductor or in other words, wireless. When I learned the introduction of Unbounded Media, the first thing came into my mind was Wi-Fi. I can imagine that the data is all over the air and some devices are used to receive the data so that Internet users can online. However, this was only my own perception and I not sure whether it was correct or not before I learned it in advance.

Basically, there are several examples of Wireless Technology such as Terrestrial Microwave, Satellite Communication, Cellular Telephony, Wi-Fi and Radio Frequency.

Chart 1 below shows the differences between these technologies.

The aspects that I am going to compare are based on these questions : -

A.) What are the equipments used?

B.) How does it work?

C.) How is the distance covered for the transmission of data?


Chart 1





Figure 1.1 : Two pairs of parabolic dish antenna, 60 feet in diameter supported on seven lattice steel girder legs












Figure 1.2 : The transmitters, receivers and power supplies were located in a single storey brick building between the pairs







Figure 1.3 : Horn Antenna



Figure 2 : Geostationary Satellite
Figure 3.1 : Mechanism of Calling from a Phone

Figure 3.2 : Mechanism of Calling from a Land Phone to a Mobile Phone



  So, here is the video clip that shows how Wi-Fi works.

video

Then, here is the classification of Radio Frequency based on different types of radio waves' propagation.

Table 1 : Different types of Radio Waves Propagation

 That's all, thanks!!










Thursday, 26 April 2012

Cabling used in Telecommunication & Networking

Wednesday, 25th April 2012
Today I was able to understand the whole lesson because it was related to something that I am able to see and imagine. Unlike previous lesson, I faced hard to understand the meaning of networking terminologies. Besides, I felt great that I had printed out the notes before our class started. I felt easier to understand Dr. Dayang’s teaching when I have the notes to refer.
So, today’s lesson was CABLING.
Cables are everywhere in our life. However, these cables are those that use in networking and we rarely notice them unless when we face networking technical problem.
Let’s start our discoveries…!!
Cabling is a type of transmission media. It is classified into two main groups – Bounded / Guided and Unbounded / Unguided.



From the above table, we notice that there are several examples of bounded media. So, next I will share about the information on these cable. 
 
a.) Twisted-pair cable can be classified into Unshielded Twisted Pair and Shielded Twisted Pair

       Unshielded Twisted Pair (UTP)
-    4 pairs of wires
-    Each is twisted with different number of twists per inch ( help eliminate interference from adjacent pairs)
-     Standard Connector to connect UTP : RJ-45 connector
-     eg. Telephone line
-     Categories of UTP :
~ Category 1 is used for voice transmission especially telephone wire
~ Category 2 is used for data transmission up to 4 Mbps (suitable for LocalTalk protocol)
~ Category 3 is used for data transmission up to 10 Mbps (suitable for Ethernet)
~ Category 4 is used for data transmission up to 16 Mbps (suitable for Token Ring)
~ Category 5 is used for data transmission up to 100 Mbps.
(* Most school use category 3 and 5. Category 5 enables fast data transmission although it is used for sharing hotspot. As for category 4, it will slow down after sharing hotspot.)

* Unshielded Twisted Pair Cable (notice that there are different number of twists per inch)

* Cross section of UTP Cable

 Shielded Twisted Pair
-          Difference with UTP:
~ 4 pairs of wires but each of them is shielded with metal shield (to prevent electromagnetic noise; thus, it looks bulky) 



* STP Cable

* Cross section of STP Cable


b.)   Co-Axial Cable
-   Different from twisted; it only has one single copper conductor at the center.
-  Conductor is surrounded by plastic insulator to separate it from the braided metal shield (to prevent electromagnetic noise and as 2nd conductor to complete the circuit.)
- Common connector used : Bayonet-Neill-Concelman (BNC) connector with different adapters (eg. T-connector)
-    Uniqueness : Suitable to use for circumstances with fluorescent lights, motors, and other computers.

* Co-axial Cable

* BNC

* T-BNC (BNC with T-connector)







Here is a video on how the BNC is connected to the Co-axial Cable.


                       video

c.)    Fiber Optics
-  Consists of a single glass core at the center surrounded by several layer of protective materials.
-   Difference with Twisted Pair and Coaxial:
~ Data transmit through light; thus, it eliminates electrical interference.
~ Able to transmit data through a longer distance.

* Fiber Optic Cable (Notice that there is light transmit through the glass core)
 

At the end of the lesson, we learned about the specific terms for cabling. The table below shows the suitable cable used in Internet with different specification. 


Thursday, 12 April 2012

Network Topology, Architecture & Protocol

Wednesday, 4th April 2012
It’s telecommunication and technology lecture again…^^
I was glad that I had done my pre-reading before we attended this lecture. This was the very first time that I had only a few enquiries on the topics that taught by Dr. Dayang. I was able to understand the whole lecture for the very first time.
I was eager to share the knowledge that I gained from this lecture.
Basically, this lecture encompassed three main topics; they were Network Topology, Network Architecture and Network Protocol. In fact, these three topics are classification of Network based on different aspects. 

Network Topology –  the study of the arrangement or mapping of the elements (links, nodes,etc.) of a network.
Network Architecture – the design of communication network. (Answer question on how data flows in a network)
Network Protocol – a common set of rules and signals that governs the communication between computers on a network.

So, based on the above definitions, are you able to differentiate these specific terms?
Let’s move on to further information.

I.)                 Network Topology 



         Topology

Aspects
Compared
Linear Bus
Ring
Star
Tree



Connections with nodes
Connected in a straight line with terminator at both ends
( linear form)
Connected in a ring without terminator because there is no end
(linear form)
Connected in star form with a central network connector called hub
(non-linear form)

Combination of Linear Bus and Star topology. Point-to-point wiring for individual segments.
(non-linear form)  
Cable used
Coaxial, Twisted Pair, Fiber
Fiber
Twisted Pair, Fiber
Coaxial, Twisted Pair, Fiber
Amount of cables need
A single continuous length of cable
A single continuous length of cable
>1 cable
>1 cable
Information transfer
Information send from a computer to the cable, follow by continuous movement along the cable. Destination computer retrieve information from the cable.
Information continuously passes from one computer to another computer until reach the destination.
Information transfer from one computer to destination computer through the hub.
-
Installation
Easy
Easy
Easy
Difficult
Addition of new workstation
Easy
Easy
Easy
Difficult
Cost
Low
Low
Higher
High
Result when cable/hub breaks down
Whole network breaks down when cable breaks down
Whole network breaks down when cable breaks down
Whole network affects a little when cable breaks down;

Whole network breaks down when the hub breaks down (if there is only 1 hub)
Network connection between point to point fails when backbone cable breaks down, but the connection within each point itself still function
Protocol used
Ethernet, LocalTalk and ATM
FDDI
Ethernet, LocalTalk and ATM
Ethernet and ATM
                      




                   Linear Bus

                     Ring
                     Star

                 
                  Tree
                 

II.)              Network Architecture

Here comes Network Architecture. At first, I was confused between Network Topology and Network Architecture because I thought that both of them are the arrangement of workstations. However, after seeking help from Dr. Dayang, I realized that Network Architecture focuses on how the data flow within the network whereas Network Topology talks about the arrangement of workstations.
There are two types of Network Architecture, which are :                                                    
i.)                  Peer-to-Peer Networks; and
ii.)                Client Server Networks

The main differences between these two Architectures can be shown by the diagram below.


^^ Client Server

^^ Peer-to-Peer

















           




                 
             
                                                                                                                                                     

III.)           Network Protocol

Basically, the main characteristics of Network Protocol are access method, allowed physical topologies, types of cabling, and speed of data transfer. Besides, there are five types of protocol : 


Ethernet                 -     Uses Carrier Sense Multiple Access/Collision Detection
(CSMA/CD) method
-          Allows Linear Bus, Star and Tree topologies
-          3 principals categories :
~ Ethernet and IEEE 802.3 (Operates at 10Mbps)
~ 100-Mbps Ethernet / Fast Ethernet (Operates at 100 Mbps)
~1000-Mbps Ethernet (Operates at 1000 Mbps / 1 Gbps)

 LocalTalk               -     Uses Carrier Sense Multiple Access with Collision Avoidance
      (CSMA/CA) method
-          Allows for Linear Bus, Star and Tree topologies
-          Transmission speed : 0.23 Mbps only (slow)

Token Ring              -     Uses token-passing as access method
-          Allows for Star-Wired Ring topology
-          Transmission speed : 4 Mbps or 16 Mbps

Fiber Distributed       -     Uses token-passing as access method
Data Interface           -     Allows Dual Ring topology
(FDDI)                        -     Transmission speed : 100 Mbps (fast)

Asynchronous            -     Allows Star topology
Transfer Mode           -     Transmission speed : > 155 Mbps (fast)
(ATM)              
                     
That’s all from me. Thanks for viewing my blog. ^^