For split bearers, the S1-U connection to the S-GW is terminated in the MeNB. PDCP data is transferred between the MeNB and the SeNB via X2-U. The SeNB and MeNB are involved in transmitting data of this bearer type over the Uu.
How LTE MAC treats MBMS differently compare to the normal user data. What different actions are taken for the MBMS specific data in the MAC layer ?