In a network, each node in the network must have its own unique address in order to distinguish itself from the others. If you wish, the IP address can be associated to some other unique identifier in real life - for example the street name or a person's phone number. In the same way that a phone number points to a person, an IP address points to a specific node inside a network.
IP addresses are created by IANA (the Internet Assigned Numbers Authority) and they're all under its management. IANA is the top level management institution. It usually allocates super-blocks to Regional Internet Registries, who in turn allocate smaller blocks to ISP's and other enterprises. The ISP's distribute individual IP addresses or subnets to their clients.
Currently, the Internet Protocol has two versions. IPv4 and IPv6. The sole term of "IP address" refers to the IPv4 one.
Internet Protocol version 4 is the fourth iteration of the Internet Protocol IP and it is the first version of the protocol to be widely deployed. IPv4 is the dominant network layer protocol on the Internet and apart from IPv6 it is the only protocol used on the Internet. On the other hand, (IPv6) is a network layer protocol for packet-switched internetworks. It is designated as the successor of IPv4, the current version of the Internet Protocol, for general use on the Internet.
The main advantage of IPv6 is that is increases the number of available IP addresses and that can be revealed by a simple math. IPv4 supports 2^32 addresses - an estimated number of 4.3 billion. That's far from enough in order for everyone to have their own IP address. On the other hand, IPv6 brings up 2^128 addresses - totaling 340 billion billion billion billions addresses. If this would be used all over the Internet, NAT will not be required anymore.
As written above, IPv4 has a 4.3 billion addresses limit and that's due its 32 bit structure. Those are not all available for public use. About 18 millions of them are for special purposes (private networks, local connections and such), not visible from the Internet cloud. Another million is translated in multi cast addresses and the number of available IP addresses drops even more.
The main thing that slows this IP address shortage is NAT (Network Address Translation), a feature that helps computers in a local network connect to the Internet Cloud and vice-versa. This is the main limitation that helped stimulating the migration towards IPv6. IPv6 is now in the early stages of deployment and is currently the only protocol that could successfully replace IPv4. And that's only a matter of time from now.
Besides NAT, there are a few other practices that help minimizing the IP address exhaustion:
* Private networks
* Dynamic Host Configuration Protocol (DHCP)
* Named based virtual hosting
* Network renumbering
It's being predicted that the unallocated IANA IP address pool will be terminated somewhere in the first half of 2010.
Ip Address ... Blog
An IP address is the unique 12 digit number sequence used to identify you over the internet. Every addressing system needs to adhere to some rules so that unique identification can be made easier. As defined by the IEEE committee, an IP address must inform the internet as to what workstation it is part of and which particular node it is of. An IP address class is a series of five different ranges, an IP of which tells the internet how big the network is.
The five different classes are ?
?Class A ? 1.0.0.0 ? 127.255.255.255
?Class B ? 128.0.0.0 ? 191.255.255.255
?Class C ? 192.0.0.0 ? 223.255.255.255
?Class D ? 224.0.0.0 ? 239.255.255.255
?Class E ? 240.0.0.0 ? 255.255.255.255
Classes A, B and C identify workstations, switches, routers and other devices. Classes D and E identify special computers. For identification of classes, the first four numbers are sufficient. Once we find out which class the IP is from, it is easy to determine the network ID and the node ID.
The classes are an estimation of network size. Class A is for very big networks, class B is medium sized network and class C is for very small networks.
Network ID and Node ID
The very existence of classes is to supply these two pieces of information. An IP address tells us which network it is a part of (Network ID) and the individual computer it is of the network (Node ID). A host ID is a single term used to combine these two ID concepts. Depending on which class the IP address is from, the host ID corresponds to a different sequence of numbers.
?For class A, the last 9 numbers are the host ID numbers.
?For class B, the last 6 numbers are host ID numbers.
?For class C, only the last 3 numbers are host ID numbers.
As you can now see, the greater the number class, the more the number of networks possible for that class, and the lesser the number of nodes in that class. For example, only 128 networks are possible for class A, though nine numbers are available for node and network IDs, implying a very large number of computers. This is exactly the opposite for Class C, since a large number of networks are present, but a very few number of nodes per network.
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