Section: 13b.3 Forwarding of user plane packets at the MBMS GW
Content: If user plane data are to be sent to the MBMS Gateway using IP unicast, the MBMS Gateway allocates an IP transport address and a separate UDP port for each MBMS bearer ( i.e the service uniquely identified by its TMGI and Flow ID and provided by the EPS to deliver the same IP datagrams to multiple receivers in a designated location). The MBMS Gateway uses that destination unicast IP address and destination UDP port of user plane packets received over the SGi-mb interface to determine on which MBMS bearer to forward the received user plane packet. If user plane data are to be sent to the MBMS Gateway using IP multicast encapsulation, the MBMS Gateway uses, the SGi-mb (transport) plane destination multicast address used and the SGi-mb (transport) plane source UDP port number provided by the BM-SC of user plane packets received over the SGi-mb interface to determine on which MBMS bearer to forward the received user plane packet.