Internet Protocol – IP

IP

The Internet Protocol (IP) is a network-layer (Layer 3) protocol in the OSI model that contains addressing information and some control information to enable packets being routed in network. IP is the primary network-layer protocol in the TCP/IP protocol suite. Along with the Transmission Control Protocol (TCP), IP represents the heart of the Internet protocols. IP is equally well suited for both LAN and WAN communications.

IP (Internet Protocol) has two primary responsibilities: providing connectionless, best-effort delivery of datagrams through a network; and providing fragmentation and reassembly of datagrams to support data links with different maximum-transmission unit (MTU) sizes. The IP addressing scheme is integral to the process of routing IP datagrams through an internetwork. Each IP address has specific components and follows a basic format. These IP addresses can be subdivided and used to create addresses for subnetworks. Each computer (known as host) on a TCP/IP network is assigned an unique logical address (32-bit in IPv4) that is divided into two main parts: the network number and the host number. The network number identifies a network and must be assigned by the Internet Network Information Center (InterNIC) if the network is to be part of the Internet. An Internet Service Provider (ISP) can obtain blocks of network addresses from the InterNIC and can itself assign address space as necessary. The host number identifies a host on a network and is assigned by the local network administrator.

When you send or receive data (for example, an e-mail note or a Web page), the message gets divided into little chunks called packets. Each of these packets contains both the sender’s Internet address and the receiver’s address. Because a message is divided into a number of packets, each packet can, if necessary, be sent by a different route across the Internet. Packets can arrive in a different order than the order they were sent in. The Internet Protocol just delivers them. It’s up to another protocol, the Transmission Control Protocol (TCP) to put them back in the right order.

There are two basic IP versions, IPv4 and IPv6

IPv4

IPv4 is the current version of the Internet Protocol (as of late 2006). Each computer or device connected to the Internet must use an IP address in order to communicate with other systems on the Internet. IPv4 distributes IP addresses in a 32-bit format, which looks like 198.162.127.111. Each three-digit section can include a number from 0 to 255, which means the total number of IPv4 addresses available is 4,294,967,296 (256 x 256 x 256 x 256 or 2^32).

Because the number of systems connected to the Internet is quickly approaching the number of available IP address, IPv4 addresses will run out soon. When you consider that there are over 6 billion people in the world and many people have more than one computer connected to the Internet, it is not surprising that roughly 4.3 billion addresses is not enough. Also, as mobile devices such as cell phones and PDAs begin to use Internet access more often, they will also require unique IP addresses.

To solve this situation, a new IP system, called IPv6, has been developed and is in the process of replacing the current IPv4 system. IPv6 addresses are 128-bit, which means there are exponentially more addresses available than IPv4. During this transitional process from IPv4 to IPv6, most systems connected to the Internet are assigned both an IPv4 and IPv6 address.

IPv6

IPv6 is also called IPng (or IP Next Generation), is the next planned version of the IP address system. IPv5 was an experimental version used primarily for streaming data. IPv6 uses 128-bit addresses, which increases the number of possible addresses by an exponential amount. For example, IPv4 allows 4,294,967,296 addresses to be used (2^32). IPv6 allows for over 340,000,000,000,000,000,000,000,000,000,000,000,000 IP addresses. That should be enough to last awhile.

Because IPv6 allows for substantially more IP addresses than IPv4, the addresses themselves are more complex. They are typically written in this format:

hhhh:hhhh:hhhh:hhhh:hhhh:hhhh:hhhh:hhhh

Each “hhhh” section consists of a four-digit hexadecimal number, which means each digit can be from 0 to 9 and from A to F. An example IPv6 address may look like this:

F704:0000:0000:0000:3458:79A2:D08B:4320

Because IPv6 addresses are so complex, the new system also adds extra security to computers connected to the Internet. Since there are so may IP address possibilities, it is nearly impossible to guess the IP address of another computer. While most computer systems today support IPv6, the new Internet protocol has yet to be fully implemented. During this transitional process, computers are often assigned both an IPv4 and an IPv6 address.