A diagram of the overall header structure in IPv6 is:
+------------+-------------------+------------+-------+---------------+
| IPv6 Header| Hop-by-Hop/Routing| Auth Header| Others| Upper Protocol|
+------------+-------------------+------------+-------+---------------+It appears after the IPv6 Hop-by-Hop header and before the
destination options.
In IPv4, the AH header follows the main IPv4 header. The diagram is:
+-------------+--------------+-------------------------------+
| IPv4 Header | Auth Header| Upper Protocol (e.g. TCP, UDP)|
+-------------+--------------+-------------------------------+
