1. 3GPP MBMS protocol stack
Group Name: ARC
Source: Echo, Huawei,
Meeting Date:
Agenda Item: WI-0002 - Architecture

2. Question
Is multicastAddress mandatory when the multicastType is 3GPP_MBMS_group?
Table : Multicast Group Information managed by group hosting CSE
Information
Multiplicity
Description
groupID 1
Indicates the <group> resource identifier which the Multicaste Group Information belongs to.
multicastType
Indicates the underlying networks multicast capability of the group members, the value shall be one of the following:
3GPP_MBMS_group,
IP_mulicast_group.
externalGroupID
0..1
If the multicastType is 3GPP_MBMS_group, the externalGroupID is the External-Group-ID as specified in 3GPP TS23.682[i.14] clause 4.6.3
multicastAddress
1??
The multicast address is allocated to the members in the memberList and shared by the members of this multicast group. The procedure of multicast address configuration is specified in RFC7390[xx]
addressType
It is used to describe the address type of the multicastAddress, e.g. IPv4 or IPv6.
multicastGroupFanoutTarget
Used as the target URI of the fan out request sending to the members.
It is a virtual identifier allocated by the group hosting CSE corresponding to the access paths (i.e. Resource-IDs, which may be different) of the member resources on the member hosting CSEs.
memberList
1(L)
List of all member resourceIDs in the multicast group. Each member resourceID corresponds to a member resource.
groupServiceServerAddress
It is used only when the multicastType is 3GPP_MBMS_group, and it is the address of 3GPP group service server (e.g. SCEF);

3. UDP shall be terminated at the GCS AS and BM‑SC.
3GPP TS29.468
7 MB2‑U Protocol
7.1 Protocol Stack
Figure 7.1-1: The user plane protocol stack without security protocols on the MB2-U reference point and in the EPC
User plane data, for instance an IP layer and UDP layer. The user plane data are transparently transported between the GCS AS and the UE. The BM‑SC shall forward these protocol layers transparently.
UDP shall be terminated at the GCS AS and BM‑SC.
IP transported by lower layers L1 and L2. These layers shall be terminated at the GCS AS and BM‑SC.
Figure 7.1‑1 depicts the MB2‑U protocol stack without security protocols. The stack shall include:
1)User plane data, for instance an IP layer and UDP layer. The user plane data are transparently transported between the GCS AS and the UE. The BM‑SC shall forward these protocol layers transparently.
-2)UDP according to IETF RFC 768 [12]. UDP shall be terminated at the GCS AS and BM‑SC.
-3)IP transported by lower layers L1 and L2. These layers shall be terminated at the GCS AS and BM‑SC.

4. User Data Plane Structure
oneM2M
Primitives
oneM2M
Primitives
User Data Plane:
Destination IP: multicastAddress
COAP
COAP
UDP
Multicast
UDP IP
Multicast IP T8
GMD
GMD
3GPP TS36.300
LET-Uu
EPC/eNB
MB2-U
UDP
HTTP
HTTP
TCP
TCP IP IP
unicast
unicast
SCEF
IN-CSE UE

5. Answer
The multicastAddress is mandatory even when the multicastType is 3GPP_MBMS_group.
Table : Multicast Group Information managed by group hosting CSE
Information
Multiplicity
Description
groupID 1
Indicates the <group> resource identifier which the Multicaste Group Information belongs to.
multicastType
Indicates the underlying networks multicast capability of the group members, the value shall be one of the following:
3GPP_MBMS_group,
IP_mulicast_group.
externalGroupID
0..1
If the multicastType is 3GPP_MBMS_group, the externalGroupID is the External-Group-ID as specified in 3GPP TS23.682[i.14] clause 4.6.3
multicastAddress
The multicast address is allocated to the members in the memberList and shared by the members of this multicast group. The procedure of multicast address configuration is specified in RFC7390[xx]
addressType
It is used to describe the address type of the multicastAddress, e.g. IPv4 or IPv6.
multicastGroupFanoutTarget
Used as the target URI of the fan out request sending to the members.
It is a virtual identifier allocated by the group hosting CSE corresponding to the access paths (i.e. Resource-IDs, which may be different) of the member resources on the member hosting CSEs.
memberList
1(L)
List of all member resourceIDs in the multicast group. Each member resourceID corresponds to a member resource.
groupServiceServerAddress
It is used only when the multicastType is 3GPP_MBMS_group, and it is the address of 3GPP group service server (e.g. SCEF);

6. Thanks for your listening! Q & A