Section: 13b.2 BM-SC interworking model of MBMS GW
Content: The control plane and user plane protocol stacks of the MBMS GW for interworking with BM-SC are illustrated in Figure 16j , Figure 16k and Figure 16l. The figures include the following protocols: - The "Diameter" SGmb application, as specified in clause 20. - The Control part of the Evolved GPRS Tunnelling Protocol for EPS, GTPv2-C, as specified in 3GPP TS 29.274[ 3GPP Evolved Packet System (EPS); Evolved General Packet Radio Service (GPRS) Tunnelling Protocol for Control plane (GTPv2-C); Stage 3 ]  [81]. - The User Datagram Protocol,UDP, as specified in IETF RFC 768 [15]. - The Transmission Control Protocol, TCP, as specified in IETF RFC 793 [18] - The Stream Control Transmission Protocol, SCTP, as specified in IETF RFC 4960 [109]. - The Packet Data Convergence Protocol, PDCP, as specified in 3GPP TS 25.323[ None ]  [107]. - The MBMS synchronisation protocol, SYNC, as specified in 3GPP TS 25.446[ MBMS synchronisation protocol (SYNC) ]  [106]. - The Internet Protocol, IP. - L1 and L2 transport protocols for IP (various options exist). Figure 16j: The control plane protocol stacks of MBMS GW for interworking with BM-SC Figure 16k: The user plane protocol stacks of MBMS GW for interworking with BM-SC for multicast Figure 16l: The user plane protocol stacks of MBMS GW for interworking with BM-SC for broadcast A BM-SC sends user plane data to an MBMS GW either by IP unicast (default), or by IP multicasting. Through the control plane communication a BM-SC provides an MBMS GW with necessary data, so that MBMS GW could forward the user plane data downlink either by multicast (default) or by unicast. PDCP is not used when the MBMS service is broadcasted in the E-UTRAN, refer to 3GPP TS 36.331[ Evolved Universal Terrestrial Radio Access (E-UTRA); Radio Resource Control (RRC); Protocol specification ]  [94].