1. Connecting to the Internet
CIT 1100
Chapter4

2. Connecting to the Internet
In this chapter you will learn how to:
Describe the hardware used to connect to the Internet
Explain protocols and software used with networking and the Internet
Discuss Web content and Web-delivered services

3. The Physical Connection
Millions of smaller networks connected together form the Internet. Like telephone network, the Internet is a "supernetwork" of smaller networks
It was designed to make certain that nothing could stop the flow of communication, not even a nuclear attack, so they specified a highly decentral­ized network with multiple connections between the various computers
The heart of the Internet- the backbone - consists of many university, corporate, and government networks, connected together via thick bundles of glass fila­ments, called fiber optic

4. Physical Connection
If the enemy destroys the central site all communications would be lost
Pre-Internet communication requires all connections to be made from a central hub
Remote sites would have dedicated connections to the central hub
message
message
message
message
message

5. Decentralized Network
Rather than having a centralized hub connection, networks were decentralized
Specialized devices were developed that would automatically route traffic to the proper destination

6. Decentralized Network
Message
Message
Message
Routers provide multiple paths to multiple end points

7. Decentralized NetworkX
FAIL
Message
In the event a cable gets cut, or a router fails the network can continue to route messages, routers can easily find alternate paths

8. Routers
Routers provide connection points between networks and determine the route for a data packet to take from the source network to destination network
Routers range from high-end machines that direct huge amounts of Internet traffic to the little box attached to your cable modem at home
Home routers often offer multiple functions, most have built-in switches and wireless access points
Routers know the destination of data because routers use TCP/IP the common protocol of the Internet
They read network ID of each data packet and send it by the shortest route they know to its destination

9. Routers
Get­ting your computer connected to the Internet requires some sort of intermediary network with a router into which you can tap. This router connects to the In­ternet through an Internet service provider (ISP)

10. Routers
Establishing a link between your computer and the ISP requires three things:
Some kind of network device on your computer, like a modem or network card
A cable or radio transmitter that enables the network device to access the world outside your door
Programs to make that hardware go, like the built-in network software in Windows and TCP/IP installed

11. ISP Connection
The least expensive Internet connection is called dial-up networking. It consists of three pieces:
A modem
A working telephone line
An ISP

12. ISDN the Other Dial-Up
Early on, people realized that computer information traveled slowly over regular analog telephone lines. The concept of an Integrated Service Digital Network (ISDN) began in1984
It was supposed to evolve into a completely digital telephone system so that data would go faster through phone lines.
ISDN never caught on as was expected because other, faster technologies soon came along such as DSL and cable
ISDN supports data transfer rates of 128 Kbps.

13. Broadband Connections
Broadband connection gives you access to the Internet through a single high-speed connection
Always on, as opposed to a dial-up connection
Two technologies dominate the broadband connection field
Cable
DSL

14. Cable
Cable connections use regular cable TV cables to delivering TV programming and high speed internet access
Supports upload speeds of up to 1.5 Mbps and download speeds from 2 to as high as 24 Mbps
Cable connections use a cable modem that connects to a NIC in your PC via an Ethernet cable
Cable TV companies take advantage of the fact that their cable TV signal occupy only a fraction of the capacity of the cables running into your home leaving room for internet access

15. DSL
DSL makes use of the fact that standard copper telephone lines can handle a much greater range of frequencies, or bandwidth, than what is needed to transmit voice during phone calls
DSL uses this extra bandwidth capacity to send data over telephone wires without disturbing their ability to carry voice conversations

16. Protocols and Settings
Once you have a physical connection to the Internet, your computer, switch, and router all start talking to one another exchanging data.
In order to know how to communicate, they need to use a predetermined lan­guage Protocols fill that need 

17. Protocols
A major issues for early computer networks have never been which pathway you use to send information. Rather, they're concerned with how you send the information so that it goes to the right place and it is understood
This became a big problem for the U.S. military, the Navy bought their computer equipment from one company, the Army from somebody else, each being proprietary
They couldn't send information back and forth, since these different systems had different ways of treating information
The Department of Defense created a common protocol that would run on any platform TCP/IP

18. Protocols
Protocols are the ”Rules of the Road” when establishing communications
Transmission Control Protocol/Internet Protocol (TCP/IP) protocol suite does the same thing for networks,
Providing a common set of rules and guidelines for electrical signals, packaging of information, error correction, security, etc.

19. TCP/IP
Transmission Control Protocol (TCP) controls the sending and receiving of information
Two computers communicating use TCP to make a con­nection and handle flow of data between them
Computers use the Internet Protocol (IP) to determine packaging and labeling of data
When data is sent its neatly cut up and packaged into bits of information that are all the same size

20. TCP/IP
The Operating System uses IP to determine how to package the data, the operating system on the receiving computer knows how to unpack the information (and how to put it back together)
To address the data so it is sent to the correct endpoint your operating system uses IP to put a numerical destination and source address-called IP addresses-onto the packets
IP addresses follow specific conventions. Most commonly, IP addresses have four sets of numbers ranging from 0 to 255, separated by periods, like this:

21. TCP/IP There are two different components to an IP address:
The Network ID defines the network
The Host ID describes your node-the computer you use to access the Internet
This came is pc .49 on the sending network, Was sent to pc .235 on the receiving network
This came from a Node on the network and was sent to the network

22. DNS
Special computers, called Domain Name Service (DNS) servers keep databases of IP addresses and their corresponding names
For example it may be hard to remember but most people can remember Google.com
When you enter into your browser the DNS server responds with the actual IP address, otherwise your browser would not be able to locate Google
For a small annual fee the ISP will maintain DNS settings allowing users to quickly locate web pages
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23. DNS lookup Open a Browser on a PC
The ISP has a DNS server that will resolve URL to an IP Address
Open a Browser on a PC
“Hey who is
That’s
The first thing that must happen is the Name must be resolved to an IP Address
DNS request

24. Let me check the pool of IP addresses and I’ll let you know
DHCP
DHCP Dynamic Host Configuration Protocol enables you to create a pool of IP addresses that are given temporarily to machines
Let me check the pool of IP addresses and I’ll let you know
Hey, I need an IP Address, also who is the DNS server and the Gateway I’ll use to send stuff to the internet?
When a PC is first turned on it transmits a request to the DHCP server (built into your home router)
IP Address:
DNS Server:
Default Gateway:
DHCP!
The PC now has an IP Address
It knows the address of the DNS server
It knows the Default Gateway to send any internet traffic to.

25. TCP/IP Services
After you've established a connection between the PC and the ISP, you can do nothing on the Internet without applications designed to use one or more TCP/IP services:
The World Wide Web
FTP (File Transfer Protocol)
VoiP (Voice over IP)
Each of these services requires a special application each having special settings

26. The World Wide Web
The Web provides a graphical interface for the Internet Web servers, providing Web sites that you access by using HTTP on port 80
Using Web-browser software, you can click a link on a Web page and be instantly connected the Web server anywhere in the world
One thing the protocol HTTP lacks is security. When you want to buy something from an online retailer you don't want someone else co­vertly capturing your credit card number
Secure Sockets Layer (SSL) security proto­col, used to create a secure connection to Web sites which has been incorporated into a secure web browser HTTPS
HTTPS is very similar to HTTP but uses a different port number 443

27. FTP
The File Transfer Protocol (FTP), using ports 20 and 21, is a protocol used to share files between systems
Instead of typing in a Web ad­dress and seeing a Web page, typing an FTP address like ftp://ftp.cise/ufl.edu brings you to a file and folder directory structure
Here, you can upload and download files (if you have permission to do so)

28. Protocols
clients, such as Microsoft Outlook need to be configured before you can use them to access your , fill in your address and password
Next you add the names of the Post Office Protocol ver. 3 (POP3) or Internet Message Access Protocol (IMAP) server and the Simple Mail Transfer Protocol (SMTP) server
POP3 or IMAP server is the computer that handles in­-coming (to you) , SMTP handles outgoing mail

29. POP3
POP3 is the most widely-used standard, although the latest version of IMAP, IMAP4, supports some newer features POP3 doesn't
IMAP4 enables you to search through messages on the mail server to find specific keywords, then select the mes­sages you want to download onto your machine
Even with the advantages of IMAP4 over POP3, the vast majority of incoming mail servers use POP3

30. VoiP
You can use Voice over IP (VoiP) to make voice calls over your computer network
Allowing you to use the extra capacity on the data network for phone calls
VoiP works with every type of high-speed Internet connection such as DSL and cable
Remember when installing VoiP is that low network latency is more important than high network speed
Latency is the amount of time a packet takes to get to its destination measured in milliseconds