Specifies the number of octets by which to increment the
OAM Echo message request size for each message request sent
when tmnxOamPingCtlTestMode is set equal to 'mtuPing'. If the
next incremented message size is greater than
tmnxOamPingCtlMtuEndSize, the last message has already been
sent. The next size message is not sent until a reply is
received or three messages have timed out at the current
size.
This parameter is optional.