The value of tmnxL2tpTgMlpppInterleave specifies
if this system applies Link Fragmentation and Interleaving to the
traffic sent from the LNS to the LAC.
If the value of this object is 'always', downstream traffic is
fragmented and interleaved, meaning that (non-fragmented) realtime
traffic is interleaved with fragments of non-realtime traffic.
If the value of this object is 'never', downstream traffic is only
fragmented but not reordered according to priority.
The value of this object is only relevant for tunnels where this system
performs the LNS role.