i have a connection to the internet using pppoe, mtu is 1480 and mru is 1480
i have l2tp client connection, mtu is 1500 and mru is 1500.
can i transport 1500 bytes packets across the l2tp tunnel or is it related to the pppoe client mtu of 1480?

bump

Yes, you can transport 1500 bytes packets across the l2tp tunnel with no fragment. The L2TP packet will be fragmented if the size is over 1480 bytes. The cost is performance.