IGMP-Mroute Proxy
UDLR-IGMP does not support the distribution of multicast groups beyond links directly connected to the downstream router.
The IGMP-Mroute proxy overcomes this by forwarding an IGMP report to an interface for each group in the multicast routing table.
In conjunction with UDLR-IGMP, IGMP reports are forwarded to an upstream router for each group in the mroute table.
To populate the unidirectional downlink router’s mroute table, other downstream routers enable PIM sparse mode and use the unidirectional downlink router as the rendezvous point.