IPv6 Hop-by-hop options header.
From RFC 2460
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Next Header | Hdr Ext Len | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +
| |
. .
. Options .
. .
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Next Header 8-bit selector. Identifies the type of header
immediately following the Hop-by-Hop Options
header. Uses the same values as the IPv4
Protocol field [RFC-1700 et seq.].
Hdr Ext Len 8-bit unsigned integer. Length of the Hop-by-
Hop Options header in 8-octet units, not
including the first 8 octets.
Options Variable-length field, of length such that the
complete Hop-by-Hop Options header is an integer
multiple of 8 octets long. Contains one or more
TLV-encoded options, as described in section
4.2.
And Options is:
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+- - - - - - - - -
| Option Type | Opt Data Len | Option Data
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+- - - - - - - - -
Option Type 8-bit identifier of the type of option.
Opt Data Len 8-bit unsigned integer. Length of the Option
Data field of this option, in octets.
Option Data Variable-length field. Option-Type-specific
data.