Fwd: Multicast Understanding

 Dear Gents,

I have a confusion regarding multicast. I am running a sparse-mode scenario
which is shown in the attached visio file.
R1 s1/0 -->R2 s1/0 (12.0.0.0/24)
R1 s1/1 -->R3 s1/0 (13.0.0.0/24)

R2 fa0/0-->R3 fa0/0(23.0.0.0/24)
R2 fa0/1 -->R3 fa0/1 -->R4 fa0/1 all on the same subnet (123.0.0.0/24)

Pim Sparse mode is running on all the common interfaces & neighbor
relationship is formed. On R2, I have a loopback (2.2.2.2) which is the RP
of the my network.

Note that I am running OSPF everywhere.

The confusion is related to the common subnet of R2,R3,R4. From what I
understood, on every common subnet one Querier,and one Forwarder is elected,
and one Designated Forwarder is Elected.As far as I understand, the Querier
is the one sending queries asking if anyone wants to join a certain group.A
forwarder is the one forwarding the stream to the subnet. The designated
router as far as I understand is the the first layer 3 device which knows
about the stream from the streamer,and sends a register message to the RP
notifying it that a source exists. Please correct me if any of my concepts
is wrong.

The router with the lowest IP address is the querier and the one with the
highest IP address is the forwarder. In the scenario I have shown, R1 is the
source, R2's loopback is the RP and R4 ethernet interface has joined a group
(239.1.1.1). When I ping from R1, I notice that the stream on R4 is being
received from both R2,and R3?Does this break the concept of forwarder?

I would be grateful for any help.

Best Regards,

KJ

-- 
KJ
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