The value of tmnxL2tpLnsTuPppLcpKaInterval specifies
the time interval in seconds at which LCP echo requests are transmitted
for this tunnel.
The value zero specifies that the actual value must be used
of the object tmnxL2tpLnsTgPppLcpKaInterval.
If the value of tmnxL2tpLnsTuPppLcpKaInterval is equal to zero, the
value of tmnxL2tpLnsTuPppLcpKaHoldUp must also be equal to zero.