There are two extension headers of this type:
Hop-by-Hop Options and Destination Options headers have the following format:
Hdr Ext Len field indicates the length of the option in 8-octet units, not including the first 8 octets. If the Hdr Ext Len field contains a value of 1 so the length of the option is 16 octets.
There are common options for both these extension headers:
These options are included in the Hop-by-Hop Options:
These options are included in the Destination Options:
Router Alert, Jumbo Payload and Home Address options are the only options which have practical use currently.