27.4 IPv6 Extension HeadersWe do not show any options with the IPv6 header in Figure A.2 (it is always 40 bytes in length), but an IPv6 header can be followed by the following optional extension headers :
We said the fragmentation header is handled entirely by the kernel, and the AH and ESP headers are automatically handled by the kernel based on the SADB and SPDB, which are maintained using PF_KEY sockets (Chapter 19). This leaves the first three options, which we will discuss in the next two sections. The API to specify these options is defined by RFC 3542 [Stevens et al. 2003]. |