Symptom
Multicast Bidir protocol: If the SVI is designated router on the switch and the SVI also happened to be a non-designated forwarder to the RP and for the traffic coming onto this SVI, bridging of multicast traffic would not happen to the receivers.
Conditions
Vlan is extended to multiple routers and on the router where SVI is a designated router on the switch, the SVI also happened to be non-designated forwarder to the RP and there are receivers on the SVI.
Creation of /32 route on the Non DF box will also not resolve this issue.
So two combinations can be there for NDF Bidir port for a vlan:
DR/NDF :This will not work as per this DDTS.
NDR/NDF:This will work in certain conditions in which NDR router gets a flood traffic .Please see cases for the NDR flood cases which is independent of Bidir in DDTS CSCvd41277
Workaround
For the links between routers, use an L3 link (SVI or pure L3 interface), different from the SVI where there are local receivers.
Further Problem Description
In a LAN segment, one DR router gets elected and the rest would be non DR routers. When we have a receiver on a SVI, L3 IGMP join would get created on the DR router. L2 snooping entry gets created on all routers (DR and non-DR routers) but L3 route (L3 IGMP join) gets created only on the DR router. But for a particular case of Bidir where SVI is a non-DF forwarder for a given RP, L3 route (L3 IGMP join) does not get created on the switch though the SVI is DR on the switch. This will cause the bridging not happen when traffic is received on this SVI, though there is an L2 entry. In a typical spine leaf topology, non-DR routers would not exist but on some other typologies where there are non-DR routers, this condition may arise.
