IP addresses IPv4 and IPv6

IP addresses (IP=Internet Protocol) Each computer connected to the Internet must have a unique IP address.

What is an IP address? 3 Every computer that communicates over the Internet is assigned an IP address (like a telephone number) that uniquely identifies the device and distinguishes it from other computers on the Internet, e.g

Mapping IP address to Domain Name 4 Because 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

Special IP Addresses? 5 Loopback IP addresses are reserved for testing on the host machine (when client and server are on the same machine), e.g localhost

Home/Private/Work Network? 6 Private network addresses are reserved for are reserved for this purpose and never used on the web, e.g and to 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 The IP4 address is divided into a network ID and host ID. Network Identifier (Network ID) (8 bits) Host Identifier (Host ID) (24 bits)

IPv4 on a PC Where 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 expands Each of the 4 decimal numbers can be between 0 and 255. They range from to 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 = possible numbers = 4,294,967,296 Appox. 4 billion

What is IPv6? 11 This gives us more IP addresses rather than using the 32-bit addressing system, it uses a 128-bit system. They range from to How many IPv6 addresses can exist?

How may IPv6 addresses are there? 256×256×256 etc. 16 times or = 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 Packets How 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 protocol 14 The Open Systems Interconnection (OSI) Model

Protocol Stacks and Packets First what is a packet!

IP Packet Structure Each 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 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 1.Say you wanted to send a message to another computer 2.The message would start at the top of the protocol stack on your computer and work it's way downward 3.On the Internet, these chunks of data are known as packets. 4.After going through the TCP layer, the packets proceed to the IP layer. This is where each packet receives it's destination address - IP address 5.ISP has a direct connection to the Internet. The ISPs router examines the destination address in each packet and determines where to send it. 6.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. 7.When the data reaches the top of the stack, the packets have been re-assembled into their original form

Activity – Complete Task 1 Add this description of data flow over the internet to task 1 for M1 and D1