Flow of Data across the internet
IP addressesIPv4 and IPv6IP addresses (IP=Internet Protocol)Each
computer connected to the Internet must have a unique IP
address.
What is an IP address?3Every computer that communicates over the
Internet is assigned anIP address (like a telephone number) that
uniquely identifies the device and distinguishes it from other
computers on the Internet, e.g.
65.52.100.214
Mapping IP address to Domain Name4Because the Internet is based
on IP addresses, not domain names, every Web server requires a
Domain Name System (DNS) server to translate domain names into IP
addresses
65.52.100.214www.microsoft.com
Special IP Addresses?5Loopback IP addresses are reserved for
testing on the host machine (when client and server are on the same
machine), e.g.127.0.0.1localhost
Home/Private/Work Network?6Private network addresses are
reserved for are reserved for this purpose and never used on the
web, e.g.192.168.1.1 and 192.168.1.2192.168.0.0 to 192.168.255.255
reserved for private networks
IP4 (Version 4) Address Structure IP (version 4) addresses are
32 bit numbers and are represented as a series of 4 decimal numbers
between 0 and 255 (256 possible numbers), separated by a period .
e.g.
227.82.157.177
The IP4 address is divided into a network ID and host ID.Network
Identifier (Network ID)(8 bits) Host Identifier (Host ID)(24 bits)
7IPv4 on a PCWhere to find IPv4 on a PC (example assigned
automatically)
IPv4 how many IP addresses?Finite number of IP address
available.More IP address required as Web expandsEach of the 4
decimal numbers can be between 0 and 255. They range from
0.0.0.0 to 255.255.255.255
How many IPv4 addresses can exist?IPv4 how many IP
addresses?Calculate the number by:
Each of the 4 decimal numbers can be between 0 and 255.
Therefore there are:256 256 256 256 = 2564 possible numbers=
4,294,967,296Appox. 4 billionWhat is IPv6?11This gives us more IP
addresses rather than using the 32-bit addressing system, it uses a
128-bit system.They range from 0.0.0.0 to
255.255.255.255.255.255.255.255.255.255.255.255.255.255.255.255
1.2.223.33.45.90.6.233.23.0.0.1.230.2.2.4
How many IPv6 addresses can exist?
1234567891011121314151612.223334590623323001230224How may IPv6
addresses are there?256256256 etc. 16 times or 25616
25616 = 340,282,366,920,938,463,463,374,607,431,768,211,456
Enough IP addresses for the Internet to continue to grow!!
Protocol Stacks and PacketsHow does you computer 'talk' to other
computers connected to the Internet?Through the use of a protocol
stack. Every computer needs one to communicate on the Internet and
it is usually built into the computer's operating system (i.e.
Windows, Unix, etc.). The protocol stack used on the Internet is
referred to as the TCP/IP protocol stack The internet
protocol14
The Open Systems Interconnection (OSI) Model Protocol Stacks and
Packets
First what is a packet!IP Packet StructureEach IP (Internet
Protocol) packet consists of a header followed by a data field. The
header length can vary between 20 and 60 bytes, and the total size
of the packet can be up to 65535 bytes. (32 bit)Actually, many
systems cannot handle packets as large as the protocol allows, and
a working maximum size is 576 bytes
IP Packet Structure
Step by Step
Say you wanted to send a message to another computerThe message
would start at the top of the protocol stack on your computer and
work it's way downwardOn the Internet, these chunks of data are
known as packets.After going through the TCP layer, the packets
proceed to the IP layer. This is where each packet receives it's
destination address - IP addressISP has a direct connection to the
Internet. The ISPs router examines the destination address in each
packet and determines where to send it. As the packets go upwards
through the stack, all routing data that the sending computer's
stack added (such as IP address and port number) is stripped from
the packets. When the data reaches the top of the stack, the
packets have been re-assembled into their original formActivity
Complete Task 1
Add this description of data flow over the internet to task 1
for M1 and D1
