Hello, everyone!
The OLT supports a distributed 2+1-level duplication architecture:
The first-level duplication is implemented on the control board. By using the "VLAN+GIP+SIP" index, the control board duplicates multicast data to the service board interested in the multicast program in an as-per-requirement manner, effectively saving the backplane bandwidth.
The second-level duplication is implemented on the service board. By using the "VLAN+GIP+SIP" index, the service board duplicates multicast data to the GPON port interested in the multicast program in an as-per-requirement manner, effectively saving the downstream bandwidth of the GPON port. Then the service board encapsulates and transmits the multicast data on the GPON port in the mode of multicast GEM port (system-level parameter, configurable, default value 4095).
The third-level duplication is implemented on the ONT. By using the "VLAN+GMAC" white list, the ONT filters out unneeded multicast data to avoid bandwidth overflow at the downstream ingress (ONT only supports that in olt-control mode). Then, by using the "VLAN+GMAC" index, the ONT duplicates the multicast data to the ONT ports in an as-per-requirement manner (only supports forwarding by using GMAC in snooping mode).
Thanks.
