Friday, 1 June 2012

Seventh Footmark on 30th May

Introduction to Internet Infrastructure


 Have the courage to act on your dreams - leave behind you the internal forces that hold you back.

Relax Corner

The Perfect Son.

A: I have the perfect son.
B: Does he smoke?
A: No, he doesn't.
B: Does he drink whiskey?
A: No, he doesn't.
B: Does he ever come home late?
A: No, he doesn't.
B: I guess you really do have the perfect son. How old is he?
A: He will be six months old next Wednesday. 


* Quite funny *

* Enjoy *

....How do I feel.... 
Today is the last day to attend this class...
It is hard to describe the feeling...
Just hope that every moments in the classroom can be kept in our mind and will not forget the effort made by our lecturer and ourselve as well...
To be sure, this subject benefits me a lot espcially the wireless technology...
We gain as much knowledge as possible...
Althought it is last lesson, the spirit on this subject will be last in our heart...

<<For beautiful eyes, look for the good in others;
for beautiful lips, speak only words of kindness;
and for poise, walk with the knowledge
that you are never alone.>>

The lesson I learned.... 

1.       Internet infrastructure
       Hierarchy of Networks:
      From a single computer to LAN
      From LAN to ISP
      From ISP to www
       In order to connect urself to the internet, u just need a few things:
      Web browser
      Internet access
       However policy & procedures to bring u to internet is quite complicated.
      Every computer that is connected to the Internet is part of a network, even the one in your home. For example, you may use a modem and dial a local number to connect to an Internet Service Provider (ISP). At work, you may be part of a local area network (LAN), but you most likely still connect to the Internet using an ISP that your company has contracted with. When you connect to your ISP, you become part of their network. The ISP may then connect to a larger network and become part of their network. The Internet is simply a network of networks.

      Most large communications companies have their own dedicated backbones connecting various regions. In each region, the company has a Point of Presence (POP). The POP is a place for local users to access the company's network, often through a local phone number or dedicated line. The amazing thing here is that there is no overall controlling network. Instead, there are several high-level networks connecting to each other through Network Access Points or NAPs.

2.       Internet Protocol (IP)

      The Internet Protocol (IP) is the principal communications protocol used for relaying datagrams (also known as network packets) across an internetwork using the Internet Protocol Suite. Responsible for routing packets across network boundaries, it is the primary protocol that establishes the Internet.

      IP is the primary protocol in the Internet Layer of the Internet Protocol Suite and has the task of delivering datagrams from the source host to the destination host solely based on the addresses. For this purpose, IP defines datagram structures that encapsulate the data to be delivered. It also defines addressing methods that are used to label the datagram source and destination.

      Historically, IP was the connectionless datagram service in the original Transmission Control Program introduced by Vint Cerf and Bob Kahn in 1974, the other being the connection-oriented Transmission Control Protocol (TCP). The Internet Protocol Suite is therefore often referred to as TCP/IP.

      The first major version of IP, Internet Protocol Version 4 (IPv4), is the dominant protocol of the internet. Its successor is Internet Protocol Version 6 (IPv6), which is increasing in use.
       Is the internet standard protocol that provide a common layer over dissimilar network
       To move packets among “host” computer tru gateways
       Every computer assign unique IP address
       IP address consist of 32 bits (shown as 4 octets of  numbers from 0-225 represented in decimal form instead of binary )
       IP add  consists of 2 part:
       Identifying the network
       Identifying the node/host
       Class of addresses determines which part belongs to the network add & which part belongs to node
       All nodes on a given network share the same network prefix but must have a unique host number
3.       Class A network

      The Class A networking address scheme is designed for the government and large institutions needing a great deal of unique nodes. Although the Class A network has only 254 unique network addresses, it can contain approximately 17 million unique nodes, which can make subnetting such a network a nightmare.

      Getting up to speed with subnetting Class A addresses requires a little forethought, some basic information, and a lot of practice. 

      This network is 8-bit network prefix. Its highest bit is set to 0, and contains a 7-bit network number and a 24-bit host number.

      A maximum of 126, which is (2 7 -2,) networks can be defined; two is subtracted because all an (0 and 1) subnet cannot be used in certain routers using RIP-1 Protocol. Each network supports a maximum of 16,777,214 (2 24 -2) hosts per network. You must subtract two because the base network represents host “0”, and the last host on the network is actually used for 1s ("broadcast") and may not be assigned to any host.

      The class A network address block contains 2 31 power (2,147,483,648) individual addresses. The IPv4 address space contains a maximum of 2 32 power (4,294,967,296) addresses, which mean that a class A network address space is 50% of the total IPv4 unicast, address space.
       Binary add start with 0 therefore decimal number can be anywhere from 1 to 126
 •       The first 8 bits (the first octet) identify the network and the remaining 24 bits indicate the host within the network.

4.       Class B network
       Binary add start with 10 = decimal number can be anywhere from 128 to 191
       The number 127 is reserved for loopback and is used for internal testing on the local machine)
       The first 16 bits (first 2 octet) = identify the network & the remaining 16 bit indicate the host 
 •      This network is a 16-bit network prefix; its highest bit order is set to 1-0. It is a 14-bit network number with a 16-bit host number.

 •      This class defines 16,384 (2 14 ) /16 networks, and supports a maximum of 65,534 (2 16 -2) hosts per network. Class B /16 block address is (1,073,741,824) = 2 30; therefore it represent 25% of the total IPV4.

5.       Class C network
       Binary add start with 110 = decimal number can be anywhere from 192 to 223
       The first 24 bits (first 3 octets) = identify the network
      This is a 24-bit network prefix; it has a 3 bit set to the highest order 1-1-0. It is a 21-bit network number with 8-bit host number.

      This class defines a maximum of 2,097,152 (2 21 ) /24 networks. And each network supports up to 254 (2 8 -2) hosts. The entire class C network represents 2 29 (536,870,912) addresses; therefore it is only 12.5 % of the total IPv4.

6.       Class D network
       Binary add start with 1110 = decimal number can be anywhere from 224 to 239
       Used to support multicasting

7.       Class E network
       Binary add start with 1111 = decimal number can be anywhere from 240 to 225
       Used for experimentation, never been documented or utilized in a standard way

       Internet service that translates domain names like into numerical IP address like
       Why we use DNS? = domain names are alphabetic (easier to remember)
      The Domain Name System (DNS) is a hierarchical distributed naming system for computers, services, or any resource connected to the Internet or a private network. It associates various information with domain names assigned to each of the participating entities. A Domain Name Service resolves queries for these names into IP addresses for the purpose of locating computer services and devices worldwide. By providing a worldwide, distributed keyword-based redirection service, the Domain Name System is an essential component of the functionality of the Internet.

      An often-used analogy to explain the Domain Name System is that it serves as the phone book for the Internet by translating human-friendly computer hostnames into IP addresses. For example, the domain name translates to the addresses (IPv4) and 2620:0:2d0:200::10 (IPv6). Unlike a phone book, however, DNS can be quickly updated and these updates distributed, allowing a service's location on the network to change without effecting the end users, who continue to use the same hostname. Users take advantage of this when they recite meaningful Uniform Resource Locators (URLs) and e-mail addresses without having to know how the computer actually locates the services.

      The Domain Name System distributes the responsibility of assigning domain names and mapping those names to IP addresses by designating authoritative name servers for each domain. Authoritative name servers are assigned to be responsible for their particular domains, and in turn can assign other authoritative name servers for their sub-domains. This mechanism has made the DNS distributed and fault tolerant and has helped avoid the need for a single central register to be continually consulted and updated. Additionally, the responsibility for maintaining and updating the master record for the domains is spread among many domain name registrars, who compete for the end-user's, domain-owner's, business. Domains can be moved from registrar to registrar at any time.

      The Domain Name System also specifies the technical functionality of this database service. It defines the DNS protocol, a detailed specification of the data structures and communication exchanges used in DNS, as part of the Internet Protocol Suite.

                                        Basics of the Domain Name System (DNS)

                                                       How does DSN work???


       IAPs (Internet access providers) 
      An Internet service provider (ISP) is an organization that provides access to the Internet.
      Internet service providers can be either community-owned and non-profit, or privately owned and for-profit.
      Access ISPs directly connect clients to the Internet using copper wires, wireless or fiber-optic connections.Hosting ISPs lease server space for smaller businesses and other people (colocation). Transit ISPs provide large amounts of bandwidth for connecting hosting ISPs to access ISPs.

      Short for HyperText Transfer Protocol, the underlying protocol used by the World Wide Web. HTTP defines how messages are formatted and transmitted, and what actions Web servers and browsers should take in response to various commands. For example, when you enter a URL in your browser, this actually sends an HTTP command to the Web server directing it to fetch and transmit the requested Web page.
        The other main standard that controls how the World Wide Web works is HTML, which covers how Web pages are formatted and displayed.
         HTTP is called a stateless protocol because each command is executed independently, without any knowledge of the commands that came before it. This is the main reason that it is difficult to implement Web sites that react intelligently to user input. This shortcoming of HTTP is being addressed in a number of new technologies, including ActiveX, Java, JavaScript and cookies

                                                           How Does the Internet Work ?    

<<<The power of one -
one thought, one action, one solution.>>>


Friday, 11 May 2012

Seventh Footmark on 10th May

Introduction to Wireless Technology

                                                                   RELAX CORNER                                                                

* Fun *

 * Good Picture *

  * Enjoy it *

Meteor Blaze... awesome!!!

Footage from Leonid Meteor Shower November 17th, 2009!!!


                                                   ...How Do I Feel....                                             

After this lesson, undoubtedly, I learned new knowledge from Dr. Dayang...

The lesson I attended making me more understand about telecommunication in particular blue tooth... so that I can wisely use it in my daily life....

Besides that, my group was the last group to do presentation....that was a good experience because the topic we did was forum and chatting...we have deeper understand about this chapter during prepare the presentation....

  *   A computer would deserve to be called intelligent if it could    
              deceive a human into believing that it was human.  *         

The lesson I learnt today....

ü  Bluetooth is an industrial specification for wireless personal area networks (PANs). Bluetooth provides a way 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. The Bluetooth specifications are developed and licensed by the Bluetooth Special Interest Group.

ü  Wireless technology
ü  Is referred to worldwide standard for the wireless exchange of data between electronic devices
ü  Created basically to solve simple problem: replacing the cables used on mobile devices with radio frequency wave
ü  This technology includes a simple low-cost and low-power global radio system
ü  IEEE develop standard 802.15 – focus on segment known as Wireless Personal Area Networks (WPAN) = based on the Bluetooth tech

ü  Bluetooth works everywhere as long as it has the hardware that compiles with Bluetooth wireless specification to ensure communication compatible worldwide.
ü  This tech allows users bring connectivity with them anywhere they go….Europe, Asia, America or other parts of the world
ü  Utilizes a radio-based =  it does not require a line of sight connection in order to communicate

ü  To establish a connection, 2 bluetooth equipped devices simply have to come within 10 meter range of each other.
ü  Before communication can happen = a device must request a connection either to accept/reject
ü  The sending device = client while the receiving devices is the server.
ü  All Bluetooth devices can operate as both client and server

ü  Concept: focused on point-to-point and point-to-multiple connection with small network called piconets.
ü  Each piconets hold up 8 active units
ü  When multiple network exist within the same room they become known as a scatternet
ü  Allows 3 types of data links between any 2 nodes:
ü  An asynchronous data channel
ü  Simultaneous voice channels
ü  Asynchronous data channels 

ü  In order to resist interference bluetooth employs spread-spectrum technique called
 frequency hopping
ü  This frequency is also used by the wireless networking standard IEEE 802.11 but operates with shorter data packets
ü  To avoid interfering with other system is by sending out very weak signal of 1 milliwatt (if u compare with the most powerful cell phone = can transmit signal of 3 watts)

ü  Low power limits the range of a Bluetooth device to about 10 meters (cutting the chances of interference between any computer system & portable telephone/tv
ü  Low power = the walls in a house would not stop a Bluetooth signal
ü  If many different Bluetooth in the room = one might think that they would interfere with one another….
ü  Several devices will be ON the same frequency at the same time = technique called spread-spectrum frequency hopping

ü  The transmitter change frequencies 1,600 times every sec = more device can make full use of the radio spectrum 

Pros & Cons of Bluetooth
          Cost of the manufacturers : components
          Too technologically advanced
          Ease of use
          Communication increase
          Support half and full duplex communication
          Low power consumption (no batteries use)
          Spread spectrum frequency hopping

Advantages and weakness of Bluetooth
Piconet & Scatternet

 Bluetooth and the future
            Bluetooth is a short range wireless technology that will be replacing cables and enabling multiple devices to connect in the near future. It acts as a bridge between obsolete and new technologies. This technology is an enabler of a range of applications at home and in the office. By using Bluetooth for connecting people, isolated microprocessors within devices and increasing programming logic, the way in which people interact with their homes and their workplaces could change drastically and dynamically.

Broadband & Infra red

-Broadband refers to a telecommunications signal or device of greater bandwidth, in some sense, than another standard or usual signal or device (and the broader the band, the greater the capacity for traffic).

-Broadband signaling method is one that includes or handles a relatively wide range (or band) of frequencies. Broadband is always a relative term, understood according to its context. The wider (or broader) the bandwidth of a channel, the greater the information-carrying capacity, given the same channel quality.

-Many computer networks use a simple line code to transmit one type of signal using a medium's full bandwidth using its baseband (from zero through the highest frequency needed). Most versions of the popular Ethernet family are given names such as the original 1980s 10BASE5 to indicate this. Networks that use cable modems on standard cable television infrastructure are called broadband to indicate the wide range of frequencies that can include multiple data users as well as traditional television channels on the same cable. Broadband systems usually use a different radio frequency modulated by the data signal for each band.[6] The total bandwidth of the medium is larger than the bandwidth of any channel 

-Definition: Infrared technology allows computing devices to communicate via short-range wireless signals. With infrared, computers can transfer files and other digital data bidirectionally. The infrared transmission technology used in computers is similar to that used in consumer product remote control units.

-Installation and Usage - Computer infrared network adapters both transmit and receive data through ports on the rear or side of a device. Infrared adapters are installed in many laptops and handheld personal devices. In Microsoft Windows, infrared connections can be created through the same method as other local area network connections. Infrared networks were designed to suppport direct two-computer connections only, created temporarily as the need arises. However, extensions to infrared technology also support more than two computers and semi-permanent networks.

-Range - Infrared communications span very short distances. Place two infrared devices within a few feet (no more than 5 meters) of each other when networking them. Unlike Wi-Fi and Bluetooth technologies, infrared network signals cannot penetrate walls or other obstructions and work only in the direct "line of sight."

-Performance - Infrared technology used in local networks exists in three different forms:
  • IrDA-SIR (slow speed) infrared supporting data rates up to 115 Kbps
  • IrDA-MIR (medium speed) infrared supporting data rates up to 1.15 Mbps
  • IrDA-FIR (fast speed) infrared supporting data rates up to 4 Mbps  

Bluetooth internet

Broadband Internet 

*All intelligent thoughts have already been thought; what is necessary is only to try to think them again.*