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Content for  TS 26.502  Word version:  17.3.0

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B  Nmb8 User Plane ingest examplesp. 55

B.1  Generalp. 55

This Annex provides an overview of the different Nmb8 User Plane protocol stacks for the distribution methods defined in clause 6. The distribution method is selected and configured at reference point Nmb2 based on Nmb10 provisioning.

B.2  Object Distribution Methodp. 55

B.2.1  Object Distribution Method with pull-based ingestp. 55

Figure B.2.1-1 illustrates a setup in which the MBS Application Provider (AF/AS) provides an object manifest to the MBSF listing the URLs of objects to be ingested and distributed. This is passed to the MBSTF at reference point Nmb2, and the MBSTF then fetches these objects using HTTP. The MBSTF handles all MBS-related complexity, e.g. converting the HTTP message payload into an IP multicast suitable protocol, adding AL-FEC, etc. The AF/AS delegates to the MBSF the delivery of MBS Service Announcement metadata to the MBS Client (i.e. IP multicast protocol details, etc).
Copy of original 3GPP image for 3GPP TS 26.502, Fig. B.2.1-1: Object Distribution Method using Pull ingest mode (HTTP GET)
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The following Parameters are used by the MBS Application Provider (AF/AS) at reference point Nmb10 to provision this setup:
  • Distribution method is set to Object.
  • Object acquisition method (property specific to the distribution method) is set to Pull.
  • Operating mode is set to OBJECT_SINGLE or OBJECT_COLLECTION or OBJECT_CAROUSEL or OBJECT_STREAMING, as appropriate.
    • OBJECT_SINGLE: Object acquisition identifiers refers to a single object.
    • OBJECT_COLLECTION: Object acquisition identifiers refers to a manifest describing the set of objects to be distributed once.
    • OBJECT_CAROUSEL: Object acquisition identifiers refers to a manifest describing the set of objects and their repetition and update pattern.
  • OBJECT_STREAMING: Object acquisition identifiers refers to a presentation manifest such as a DASH MPD. The MBSTF pulls the objects according to the presentation manifest.
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B.2.2  Object Distribution Method with push-based ingestp. 56

Figure B.2.2-1 illustrates a setup in which the MBS Application Provider (AF/AS) pushes objects directly into the MBSTF at Nmb8 using HTTP PUT. The MBSTF handles all MBS-related complexity, e.g. converting the HTTP message payload into an IP multicast suitable protocol, adding AL-FEC, etc. The AF/AS delegates MBS delivery of Service Announcement metadata destined for the MBS Client (i.e. DASH MPD, IP multicast protocol details, etc.) to the MBSTF via MBSF.
Copy of original 3GPP image for 3GPP TS 26.502, Fig. B.2.2-1: Object Distribution Method using Push ingest mode (HTTP PUT)
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The following MBS Distribution Session properties are used by the MBS Application Provider (AF/AS) at reference point Nmb10 to provision this setup:
  • Distribution method is set to Object.
  • Object acquisition method is set to Push.
  • Operating mode is set to OBJECT_SINGLE or OBJECT_STREAMING, as appropriate.
    • OBJECT_SINGLE: Each pushed object is distributed once.
    • OBJECT_COLLECTION: Not used.
    • OBJECT_CAROUSEL: Not used.
    • OBJECT_STREAMING: Each pushed object is distributed once.
  • Distribution operating mode is set to File or Collection or Carousel or Real-time, as appropriate.
  • Object acquisition identifiers contains the Push base URL used to ingest objects. The MBSF provides the Push base URL (property specific to the distribution method) to the MBS Application Provider (AF/AS).
  • Distribution base URL contains the base URL for the objects. The MBSF replaces the Push base URL part of the object ingest URL with the value of the Distribution base URL for inclusion in FLUTE FDT instance(s) and (in some cases) in the Service Announcement.
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B.3  Packet Distribution Methodp. 57

B.3.1  Proxy modep. 57

Figure B.3.1-1 illustrates a setup in which the MBS Application Provider (AF/AS) injects UDP datagrams directly into the MBSTF at reference point Nmb8. The MBSTF handles all MBS-related complexity, e.g. restamping the UDP datagram headers and/or the IP packet headers, as required for distribution. The MBSTF is not required to process the UDP payload of packets ingested at reference point Nmb8.
Copy of original 3GPP image for 3GPP TS 26.502, Fig. B.3.1-1: Packet Distribution Method using Proxy mode
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The following MBS Distribution Session properties are used by the MBS Application Provider (AF/AS) at reference point Nmb10 to provision this setup:
  • Distribution method is set to Packet.
  • Operating mode is set to PACKET_PROXY.
    • Packet ingest method is set to Multicast or Unicast.
    • When the Packet ingest method indicates Multicast ingest, then either the MBS Application Provider (AF/AS) nominates the multicast IP address and UDP port(s) to be used for reception at reference point Nmb8, or else the MBSF allocates these values.
    • When the Packet ingest method indicates Unicast ingest, the MBSTF allocates a UDP reception port for use at reference point Nmb8 and provides the reception UDP port together with the reception IP address to the MBS Application Provider (AF/AS) via the MBSF.
A unicast ingest packet delivery protocol is established at reference point Nmb8 that allows the control of the unicast stream.
The MBSTF processes the UDP packet payloads received by the Packet ingest subfunction and creates MBS-4-MC packets as described in clause 4.3.3.3. The MBSTF encapsulates these packets into the Nmb9 tunnel.
  • The MBSF nominates the MBS-4-MC multicast group destination IP address and UDP ports to be used inside the Nmb9 unicast tunnel in the User plane traffic flow information.
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B.3.2  Forward-only modep. 58

Figure B.3.2-1 illustrates a setup in which the MBS Application Provider (AF/AS) injects multicast IP packets encapsulated in a unicast UDP/IP tunnel directly into the MBSTF. The MBSTF decapsulates the multicast IP packets from the tunnel and forwards them unmodified to the MBS Session at reference point Nmb9.
Copy of original 3GPP image for 3GPP TS 26.502, Fig. B.3.2-1: Packet Distribution Method using Forward-only mode
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The following MBS Distribution Session properties are used by the MBS Application Provider (AF/AS) at reference point Nmb10 to provision this setup:
  • Distribution method is set to Packet.
  • Operating mode is set to PACKET_FORWARD_ONLY.
  • Packet ingest method is set to Unicast.
  • User plane traffic flow information is omitted because ingested multicast packets are not modified.
The MBSTF provides the MBSTF ingest endpoint addresses via the MBSF to the MBS Application Provider (AF/AS) so that it can establish the UDP/IP tunnel with the MBSTF and start sending tunnelled IP packets.
A unicast ingest packet delivery protocol is established at reference point Nmb8 that allows the control of the unicast stream.
The MBSTF Packet ingest subfunction receives ready-made multicast UDP/IP packets from the MBS Application Provider (AF/AS) at reference point Nmb8.
  • When no FEC configuration is provided, the MBSTF pushes the packets into the Packet scheduling subfunction (see clause 4.3.3.3). The MBSTF encapsulates these packets into the Nmb9 tunnel for transmission to the MB-UPF.
  • When an FEC configuration is provided, the MBSTF parses deep into the UDP payload to create AL-FEC redundancy. Source block marking is appended to source packets and the packet length fields are adjusted in UDP and IP headers. AL-FEC redundancy is inserted into the stream according to the FEC configuration. The resulting packets are handled by the Packet scheduling subfunction (see clause 4.3.3.3). The MBSTF encapsulates these packets into the Nmb9 tunnel.
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