Re: Multicast Understanding

yep.

highest is the DR. but lowest ip address needn't necessarily forward
multicast traffic onto the broadcast domain.1

The assert election criteria are as follow in decreasing order of priority:

1- administrative distance to the source S (10.10.10.1)

2- Cost of the route to S (10.10.10.1)

3- Highest multicast interface IP address.

refer http://cciethebeginning.wordpress.com/2008/07/16/pim-assert-message/

On Sun, Oct 11, 2009 at 3:59 PM, karim jamali <karim.jamali_at_gmail.com>wrote:

> 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
>
>
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