Each conceptual row presents an operations interface to drain
a Layer Two Tunneling Protocol Tunnel Group.
After a successful drain operation, the value of the object
tmnxL2tpTgStatState of this tunnel group is equal to 'drain', and
the value of the object tmnxL2tpTuStatusState is equal to 'draining' for
all the tunnels of this L2TP tunnel group; none of these tunnels accept
or establish new connections, while existing connections are timing out.
Entries in this table are created and destroyed by the system.