20130911

Fundamentals of IP Address

IP Address:

This is a numerical label assigned to each device participating in a computer network that uses Internet Protocol for communication. The functions of IP address are to identify the host or network interface, & location address.

Internet Protocol Version 4: (Standard: RFC 791)

This protocol uses a 32 bit number to identify computers connected to the internet. Computers do all the internal calculations using a binary number system in which each digit is either a 0 or a 1, corresponding to a state of either OFF or ON.  IP Version 4 allows more than 4 billion different addresses, as 2³² = 4, 294,967,296. When a router breaks a message into packets before sending it onto the internet, the router marks each packet with both the source & destination IP addresses of the message. Each IP address appears as 4 numbers separated by periods specified under the dotted decimal notation system, & each of the 4 numbers is an 8 bit number. In networking applications, an 8 bit number is called an octet, & in binary, an octet can have values from 00000000 to 11111111, & the decimal equivalents of these binary numbers are 0 and 255 respectively. As each of the 4 parts of a dotted decimal number can range from 0 to 255, IP addresses range from 0.0.0.0 (32 zeros in binary) to 255.255.255.255 (32 ones in binary).
IP4 is a connectionless protocol to be used on packet switched networks, & it operates on a best effort delivery model, wherein it does not guarantee delivery, nor does it assure proper sequencing or avoidance of duplicate delivery. These aspects along with data integrity are taken care of by an upper layer transport protocol, called as Transmission Control Protocol.

Internet Protocol Version 6: (Standard: RFC 2460)

The limited addressing capacity of 'Internet Protocol Version 4' created the new internet protocol version called 'Internet Protocol Version 6'. Though the IP4 and IP6 are not directly compatible to each other, network engineers have devised ways and means to run both protocols simultaneously on interconnected networks. The advantage of IP6 is that it uses a 128 bit number for addresses, & hence the number of available addresses in IP6 is ₂¹²⁸ = 34 followed by 37 zeros, which is billion times more than the address space of IP4. The IP6 notation uses 8 groups of 16 bits. Each group is expressed as 4 hexadecimal digits & the groups are separated by colons, & hence this is called 'colon hexadecimal system'. Hexadecimal numbering system uses 16 digits, viz. 0,1,2,3,4,5,6,7,8,9,a,b,c,d,e,&f.
An example is: AB17:0000:2222:0000:3434:CD56:F9889:76D2, & to save space, the zeros can be omitted to: AB17:2222:3434:CD56:F9889:76D2.
IP6 is an internet layer protocol for packet switched networks and provides end to end data transmission across multiple IP networks, adhering to the design principles of IP4.

IP Address Allocation:

The IP address management tasks were originally with "Internet Assigned Numbers Authority (IANA)", which then delegated the allocation of IP address blocks to (1) American Registry for Internet Numbers for USA, Canada, Antarctica, & some parts of Carribbean, (2) African Network Information Center for Africa, (3) Asia-Pacific Network Information Center for Asia, Australia, New Zealand & adjacent countries, (4) Latin America & Carribbean Network Information Center for Latin America & parts of Carribbean, & (5) Reseaux IP Europeens Network Coordination Center for Europe, Russia, Middle East, & Central Asia. 

IP Address Subnetting:

As the demand for IP addresses increased due to use of mobiles, tablets, laptops, & other wireless devices, techniques to stretch the supply of IP addresses were devised, & the best out of all was subnetting. Three IP4 address ranges have been reserved for private networks, & these are not routed through the internet, & thus their use need not be coordinated with IP address registry. If required, these private networks typically connect to the internet through network address translation. Morefully, in subnetting, a computer called network address translation converts those private IP addresses to normal IP addresses when it forwards packets to the internet from those computers.
    
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