Hello Forum,
Looking for a guru who knows about PIM and how Mikrotik uses RP candidates.

Hardware is Mikrotik R82011UiAS-RM running os6.49.7

Summary - A situation arises when a router is connected to the network infrastructure and it has a higher "RP candidate" priority than the current RP router.

In the test environment I have routers setup as follows;

Multicast source A --- LAN-A ---- ROUTER-A (RP) --- SHARED SEGMENT
|
Multicast source B --- LAN-B ---- ROUTER-B -------- SHARED SEGMENT
|
Multicast source C --- LAN-C ---- ROUTER-C -------- SHARED SEGMENT

Each multicast source uses a unique group address.
Each LAN segment has a multicast listener for each group address.
At this point, all LAN segments are correctly receiving all multicast streams.


I now power on ROUTER-D. ROUTER-D has a higher RP candidate priority than ROUTER-A and takes over the RP role.

Multicast source A --- LAN-A ---- ROUTER-A -------- SHARED SEGMENT
|
Multicast source B --- LAN-B ---- ROUTER-B -------- SHARED SEGMENT
|
Multicast source C --- LAN-C ---- ROUTER-C -------- SHARED SEGMENT
|
Multicast source D --- LAN-D ---- ROUTER-D (RP) --- SHARED SEGMENT


At this point, Multicast Source A is now only received by the LAN-D listener. The LAN-B and LAN-C listeners no longer receive the stream from Multicast source A.


Observations.
1. When I look at the MFC table on ROUTER-D (RP), the entry for the Multicast stream from LAN-A has an outgoing interface of BRIDGE - all the other streams have an outgoing interface of both BRIDGE and ETHER1.

2. If I look at the PIM Joins table (on any of the routers), there is an entry for the Multicast Stream A, if I open that entry I note the following details;
Upstream MRIB Nexthop 10.255.1.1 (ROUTER-A)
Upstream PIM Nexthop 10.255.1.1 (ROUTER-A)
Assert Loser - ETHER1


If I don't perform any actions, Multicast Stream A never be received by any listener except for the LAN-D listener.

Recovery actions.
1. If I stop the Multicast source A stream for a few minutes and then restart it, all sites then receive it correctly.
2. If I establish a new multicast stream on LAN-A (with a new group address), all sites then receive it correctly - but the initial stream is still not received.


Setup Information.
For each router, Port ether1 connects to the shared segment
For each router, Port ether3 connects to the local network
OSPF routing is enabled and working correctly
PIM is enable on ether1 (PIM) and Bridge (PIM, IGMP)
Each router is configured as a RP candidate and as a BSR candidate.