MLPPPoE is the only session type in the last mile that is supported:
MLPPPoE can be a single physical link or multilink. The last mile encapsulation is Ethernet over copper (This could be Ethernet over VDSL or HSDSL). The access rates (especially upstream) are still limited by the xDSL distance limitation and therefore, interleaving is required on a slow speed single link in the last mile. It is possible that the last mile encapsulation is Ethernet over fiber (FTTH) but in this case, users would not be concerned with the link speed to the point where interleaving and link aggregation is required.
Finally, this is the slow link of the last mile, the reason why LFI is performed in the first place. Assuming that LFI played its role in the network as designed, by the time the transmission of one fragment on this link is completed, the next fragment arrives just in time for unblocked transmission. In between the two fragments, we can have one or more small high priority packets waiting in the queue for the transmission to complete.
We can see on the AN-RG link in Figure 2 that packets P2 and P3 are ahead of fragments F2 and F3. Therefore the delay incurred on this link by the low priority packets is never greater than the transmission delay of the first fragment (50ms). The remaining two fragments, F2 and F3, can be queued and further delayed by the transmission time of packets P2 and P3 (which is normally small, in our example 3ms for each).
If many low priority packets were waiting in the queue, then they would have caused delay for each other and would have further delayed the fragments in transit from the LNS to the LAC. This condition is normally caused by bursts and it should clear itself out over time.
MLPPP(oEo)A can be a single physical link or multilink. The last mile encapsulation is ATM over xDSL.
Some other combinations are also possible (ATM in the last mile, Ethernet in the aggregation) but they all come down to one of the above models that are characterized by:
Ethernet or ATM in the last mile.
Ethernet or ATM access on the LAC.
MLPPP/PPPoE termination on the LNS