The value of tmnxL2tpApNasPortTypeValue specifies
what value will be put in the RADIUS NAS-Port-Type attribute
if included in RADIUS accounting-request messages.
This field is only applicable if the 'nasPortType'
bit is set in tmnxL2tpApIncludeAttributes and the value of the object
tmnxL2tpApNasPortTypeType is equal to 'config'.