Special Edition Using TCP/IP, Second Edition

IPv6 Extension Headers

As stated earlier, an extension header enables additional functionalities to be implemented while transmitting a datagram. These extension headers are placed between the basic header and the payload data in the datagram. There are six different types of headers that can be placed in an IP datagram. They are as follows:

• Hop-by-Hop Options

• Routing

• Fragmentation

• Destination Options

• Authentication

• Encapsulated Security Payload

An IP datagram can contain more than one extension header. Two important points that need to be considered about the processing of extension headers are as follows:

• The extension headers are processed only at the final destination of the datagram with the exception of the Hop-by-Hop Options ...