What is an IPv6 Address?

IPV6 (Internet Protocol Version 6) is the most recent version of the Internet Protocol. In 1988, IPv6 was developed by the Internet Engineering Task Force (IETF) to deal with the running out problem of IPV4. Another reason for introducing IPV6 was because IPV4 has no encryption and authentication provided.

Features of IPV6

  • It provides end-to-end transmission of data across multiple IP networks.
  • It has support for real-time services.
  • It has improved security compared to IPV4.
  • It also supports mobile IP.

IPV6 Address Size

It has an address space of 128-bit. Meaning it can support 340 trillion, trillion, trillion addresses.

IPV6 Address Format

2003 BD3F AB10 FEF7 0000 0000 0000 BDE7

IPV6 Header

IPv6 fixed header is 40 bytes long and contains the following information:

Version: It represents the version of IP, i.e. 1011.

Traffic Class: 8 bits are divided into 2 parts. First, 6 bits are used for Type of Service to let the Router know what services should be provided. Lastly, 2 bits are used for Explicit Congestion Notification (ECN).

Flow Label: It is used to maintain the flow of the packet. The source helps the router identify that a packet belongs to a specific flow. This helps avoid re-ordering of data packets.

Payload Length: It tells the routers how much information packet contains. It is composed of Extension Headers and Upper Layer data. If the Extension Headers contain Hop-by-Hop Extension Header, then the payload may exceed 65535 bytes and this field is set to 0.

Next Header: It is used to show either the type of Extension Header or if the Extension Header is not present then it indicates the Upper Layer PDU. The values are the same as IPv4.

Hop Limit: It is used to stop packets to loop in the network infinitely. It is the same as TTL in IPv4. When the field reaches 0 the packet is discarded.

Source Address: It shows the address of the originator of the packet.

Destination Address: It provides the address of the intended recipient of the packet.

Size of Traffic Class

The size of the Traffic Class is 8-bits.

Size of Flow Label

The size of the Flow Label is 20-bits.

Size of Payload Length

The size of Payload Length is 16-bits.