IPv6 is designed in order to minimize the fragmentation. It is closely related to the length of outgoing datagrams. Each datagram should be as large as possible to avoid the network overload due to sending a large number of smaller datagrams. But the datagram length also may not exceed path MTU. To find the ideal datagram length, the Path MTU Discovery algorithm is used. The RFC 1981 defines this algorithm.
To find the ideal datagram length, the Path MTU Discovery algorithm proceeds as follows:
This algorithm should be repeated at certain intervals, because the path MTU can be increased during communication. The recommended interval is 10 minutes.