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An IP(Internet Protocol) address is a unique identifier for a node or host connection on an IP network.

An IP address is a 32 bit binary number usually represented as 4 decimal values, each representing 8 bits, in the range 0 to 255(Known as Octets) separated by decimal points.

This is known as “DOTTED DECIMAL ”notation.

Example: 140.179.220.220 It is some times useful to view thevalues in

their binary form. 140 .179 .220 .220 10001100 .10110011 .11011100 .11001000 Every IP address consists of two parts,one

identifying the network and one identifying the node.

Unreliable and connectionless datagram

protocol. It provides no error control or flow control.

If reliability is important IPv4 must be paired with a reliable protocol such as TCP.

IPv4 is a connectionless protocol for a packet

switching network that uses the datagram approach.

Some could lost or corrupted during transmission.

IPv4 relies on a higher level protocol to take care of all these problem.

Each datagram is handled independently, and each datagram can follow a different route to the destination.

This implies that the datagram sent by the same source to the same destination could arrive out of order.

Address depletion is still a long term problem in the Internet.

The Internet must accommodate real time audio and video transmission. This type of transmission requires minimum delay strategies and reservation of resources.

No encryption or authentication of data is provided by IPv4.

Version The IP version

number, 4.

Length The length of the

datagram header in 32-bit words.

Options: A list of optional specifications for

security restrictions, route recording, and source routing. Not every datagram specifies an options field.

Padding: Null bytes which are added to make the

header length an integral multiple of 32 bytes as required by the header length field

Total length : The length of the datagram in bytes including the

header,options and the appended transport protocol segment or packet.

Type of service Contains five subfields that specify the precedence,

delay, throughput, reliability, and cost desired for a

packet. (The Internet does not guarantee this request.) This field

is not widely used on the Internet.

Identification An integer that identifies the datagram.

Time to live: How many routers a datagram can pass through.

Each router decrements this value by 1 until it reaches 0 when the datagram is discarded. This keeps misrouted datagrams from remaining on

the Internet forever. protocol The high-level protocol type.

FLAGS: Controls datagram fragmentation together with

the identification field. The flags indicate whether the datagram may be fragmented, whether the datagram is fragmented, and whether the current fragment is the final one.

FRAGMENT OFFSET:

The relative position of this fragment measured from the beginning of the original datagram in units of 8 bytes.

HEADER CHECKSUM: A number that is computed to ensure

the integrity of the header values. SOURCE ARRDESS: The 32-bit IPv4 address of the

sending host. DESTINATION ADDRESS: The 32-bit IPv4 address of the

receiving host.

The apparent discontinuity in

numbering is the result of version number 5 being

used for an experimental protocols some years ago.

IPv6 (Internetworking Protocol version 6),also known as IPng (Internet Protocol, next generation), was proposed and is known as a standard.

The format and the length of the IP address were changed along with the packet format.

Larger address space: An IPv6 address is 128 bits long .

Better header format: New header format in which options are separated from the

base header and inserted, when needed, between the base header and the upper layer data.Simplifies and speeds up the routing process because most of the options do not need to be checked by routers.

New options:

IPv6 has new option to allow for additional functionalities.

Allowance for extension:

Designed to allow the extensions of the protocol if required by new technologies or applications.

Support for resource allocation: In IPv6, the type of service field has been removed, but a

mechanism (called flow label) has been added to enable the source to request special handling of the packet. This mechanism can be used to support traffic such as real time audio and video.

Support for more security : The encryption and authentication options in IPv6 provide

confidentiality and integrity of the packet.

End-to-end dual-stack for IPv6 and IPv4 IPv6 and IPv4 stateful firewall for small and large sites Multiple address allocation and tunneling mechanisms

for IPv4/IPv6 corporate access and IPv4 Internet access CPE with integrated IPv6 IPSec VPN support Tunnel and Transition schemes eg NAT-PT, 6to4, 4to6 Service Provider IPv6 DSL Subscriber Management Service Provider IPv6 edge and core routing in

hardware

BASE HEADER: Base Header includes eight fields. These fields

are as follows:1. VERSION: This 4 bit field defines the version number of the

IP. For IPv6, the value is 6 .2. PRIORITY: This 4 bit field defines the priority field of the

packet with respect to traffic congestion.

3. PAYLOAD LENGTH:

The 2 byte payload length field defines the length of the IP data gram excluding the header.

4. NEXT HEADER:

The Next header field is an 8 bit field defining the header that follows the base header in the datagram. The next header is either one of the optional extension headers used by IP or the header of an encapsulated packet such as UDP or TCP. Each extension header also contains this field. This field in Version 4 is called the Protocol.

FLOW LABEL: The flow control is a 3 byte(24 bits) field that

is designed to provide special handling for a particular flow of data.

DESTINATION ADDRESS: The destination address field is 16 byte (128

bits) Internet address that usually identifies the final destination of the datagram.

HOP LIMIT :

This 8 bit hop limit field serves the same purpose as the TTL field in IPv4.

SOURCE ADDRESS:

The source address field is 16 byte (128 bits) Internet address that usually identifies the original source of the datagram.

Users IPv4 Services

Public/Private IPv6 network

Public IPv4 Internet

Users

NAT 6/4

Sub net Sub net Sub net Sub net Sub netSub net

InternetInternet

Interactive (e.g. VoIP) session