Embedded RP IPv6 Multicast

Hi Andrew,

I checked with 3 nodes R1—R2—R3 and it worked properly. R1 (source), R2 (RP) and R3 (receiver)
What i don’t understand is if R1 is sending the MCAST traffic, then who is DR in this scenario? R2? Who actually is sending the unicast register messages towards RP? A little bit confusing this scenario.

I’m regular to some basic setup where R5—R1—R2—R3—R7 where (R5 is a source), (R1 a DR), (R2 is and RP), (R3 is a last hop router connected to receiver), (R7 is a receiver)

But what i found out is if i test with 5 devices than it’s not working and DR is showing all the time the following mroute output:
like it’s sending the registering messages all the time but RP is not seeing them at all, it only sees join from R7!

****R1*****

R1#show ipv6 mroute    
Multicast Routing Table
Flags: D - Dense, S - Sparse, B - Bidir Group, s - SSM Group, 
       C - Connected, L - Local, I - Received Source Specific Host Report,
       P - Pruned, R - RP-bit set, F - Register flag, T - SPT-bit set,
       J - Join SPT, Y - Joined MDT-data group,
       y - Sending to MDT-data group
       g - BGP signal originated, G - BGP Signal received,
       N - BGP Shared-Tree Prune received, n - BGP C-Mroute suppressed,
       q - BGP Src-Active originated, Q - BGP Src-Active received
       E - Extranet
Timers: Uptime/Expires
Interface state: Interface, State

(2001:1:5::5, FF78:240:FC00:2:2:2:0:A), 00:00:04/00:03:25, flags: SFT
  Incoming interface: GigabitEthernet1.15
  RPF nbr: FE80::250:56FF:FE92:5, Registering
  Immediate Outgoing interface list:
    Tunnel0, Forward, 00:00:04/never

****RP*****

R2#show ipv6 mroute      
Multicast Routing Table
Flags: D - Dense, S - Sparse, B - Bidir Group, s - SSM Group, 
       C - Connected, L - Local, I - Received Source Specific Host Report,
       P - Pruned, R - RP-bit set, F - Register flag, T - SPT-bit set,
       J - Join SPT, Y - Joined MDT-data group,
       y - Sending to MDT-data group
       g - BGP signal originated, G - BGP Signal received,
       N - BGP Shared-Tree Prune received, n - BGP C-Mroute suppressed,
       q - BGP Src-Active originated, Q - BGP Src-Active received
       E - Extranet
Timers: Uptime/Expires
Interface state: Interface, State

(*, FF78:240:FC00:2:2:2:0:A), 00:09:32/00:03:01, RP FC00:2:2:2::2, flags: S
  Incoming interface: Tunnel2
  RPF nbr: FC00:2:2:2::2
  Immediate Outgoing interface list:
    GigabitEthernet1.23, Forward, 00:09:32/00:03:01

And finally i just started to send ping from R1 (DR) towards MCAST group and ping worked properly!

R1#ping FF78:240:FC00:2:2:2:0:A
Output Interface: GigabitEthernet1.12
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to FF78:240:FC00:2:2:2:0:A, timeout is 2 seconds:
Packet sent with a source address of 2001:1:2::1

Reply to request 0 received from 2001:3:7::7, 53 ms
Reply to request 0 received from 2001:3:7::7, 54 ms
Reply to request 0 received from 2001:3:7::7, 91 ms
Reply to request 0 received from 2001:3:7::7, 92 ms

So it means that when i add another router between source and RP then all the stuff stops working! But this doesn’t make sense as it should work as well! what i add is a DR who should register first the mcast in unicast messages towards RP… Or i miss something general in ipv6 mcast?

Do you have any suggestions regarding this? Did you try to add another node between source and RP?

Please reply.

Thanks,
Vladimir