IPv6

Next Generation IP (IPv6)
There are several reasons for the need of a new Internet Protocol (IPv6):
- The main reason was the address depletion.
- Other reasons are related to the slowness of the process due to some unnecessary processing, the need for new options, support for multimedia, and the desperate need for security.
IPv6 protocol responds to the above issues using the following main changes in the protocol:
? Larger address space: An IPv6 address is 128 bits long.
? Better header format: IPv6 uses a 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.
? New options: IPv6 has new options to allow for additional functionalities.
? Allowance for extension: IPv6 is designed to allow the extension 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 two new fields, traffic class and flow label have 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.
Packet Format
Each packet is composed of a base header followed by the payload. The base header occupies 40 bytes, whereas payload can be up to 65,535 bytes of information.
The description of fields follows:
? Version: The 4-bit version field defines the version number of the IP. For IPv6, the value is 6.
? Traffic class: The 8-bit traffic class field is used to distinguish different payloads with different delivery requirements. It replaces the type-of-service field in IPv4.