Section: 8.73 MBMS IP Multicast Distribution
Content: The MBMS IP Multicast Distribution IE is sent by the MBMS GW to the MME/SGSN in the MBMS Session Start Request. Source Specific Multicasting is used according to IETF RFC 4607 [40]. The IP Multicast Distribution Address and the IP Multicast Source Address fields contain the IPv4 or IPv6 address. The Address Type and Address Length fields shall be included in each field: - The Address Type, which is a fixed length code (of 2 bits) identifying the type of address that is used in the Address field. - The Address Length, which is a fixed length code (of 6 bits) identifying the length of the Address field. - The Address, which is a variable length field shall contain either an IPv4 address or an IPv6 address. Address Type 0 and Address Length 4 shall be used when Address is an IPv4 address. Address Type 1 and Address Length 16 shall be used when Address is an IPv6 address. Other combinations of values are not valid. MBMS HC Indicator represents an indication if header compression should be used for MBMS user plane data, as specified in 3GPP TS 25.413[ UTRAN Iu interface Radio Access Network Application Part (RANAP) signalling ]  [33]. MBMS HC Indicator field is encoded as a one octet long enumeration. NOTE: Currently, 3GPP TS 25.413[ UTRAN Iu interface Radio Access Network Application Part (RANAP) signalling ]  [33] specifies two enumeration values: 0 (indicates "uncompressed-header") and 1 (indicates "compressed-header"). Common Tunnel Endpoint Identifier is allocated at the source Tunnel Endpoint and signalled to the destination Tunnel Endpoint. There is one Common Tunnel Endpoint Identifier allocated per MBMS bearer service. The recommendations on how to set the value of C-TEID are provided in 3GPP TS 23.246[ Multimedia Broadcast/Multicast Service (MBMS); Architecture and functional description ]  [37]. Figure 8.73-1: MBMS IP Multicast Distribution