2.2.14 SPM Packet

This packet is sent by the server on multicast address and provides status of the multicast session.

SPMSeqNo (8 bytes): MUST be set to an 8-byte numeric value that is incremented by 1 with each successive SPM packet. The value for the first SPM packet sent by the server MUST be set to 1.

MasterClientId (4 bytes): MUST be set to a numeric value specifying the unique ID of the client that is to act as the Master Client and MUST reply using an ACK packet.

MinNACKBackOff (2 bytes): Specifies minimum time in milliseconds that the client MUST wait before sending a NACK packet to server. The Master Client MUST NOT use the MinNACKBackOff field, and MUST immediately send a NACK packet if packet loss is detected.

MaxNACKBackOff (2 bytes): Specifies maximum time in milliseconds that the client MAY wait before sending a NACK packet to server.

TrailODATASeqNo (8 bytes): MUST specify the lowest ODATASeqNo for ODATA packet that is available to clients for retransmission. The clients MAY send a NACK packet to the server for any ODATA packet in range from TrailODATASeqNo and LeadODataSeqNo (inclusive) and the server MAY send the requested packets as RDATA packets.

LeadODATASeqNo (8 bytes): MUST specify the highest ODATASeqNo for the ODATA packet that has been sent by server.

RTT (2 bytes): MUST be set to the round trip time in milliseconds for the Master Client.

This packet does not have any Extended Options.