Multicast IGMP Proxy

Lessons Discussion
21

seems the interface gi0/2 is missing on R3 in diagram.
Please fix.

22

Hello Manoj

Yes, you are correct, I’ll let Rene know to make the correction…

Thanks for pointing that out!

Laz

1 Like
23

Thanks @manojkumar.sk I just fixed this.

Rene

1 Like
24

Hi,

I’m still confused why R1 as IGMP querier? can you try explain more detail about IGMP querier?

Thanks

25

Hello Jisooya

In a multicast topology, an IGMP querier exists on every subnet or network segment. In this particular topology, R1 is the IGMP querier for the subnet on which S1 resides. Here there is no choice, since it is the only multicast router in the segment. For the segment between R1 and R2, either R1 or R2 can be elected as the querier. However, as Rene states in the lesson, R1 must be chosen as the querier in order for this IGMP proxy setup to function correctly. From the output of R1 and R2, you can see that R1 is set as the querier for both network segments.

For more about the querier election process take a look at this lesson:

Note that a querier exists only for IGMPv2 and IGMPv3. IGMPv1 does not use this feature.

I hope this has been helpful!

Laz

26

Hello.
On the topology image you have 2 Gi0/2 interfaces for R2

Also, why is this one been configured to the sparse-mode ?

R2(config)#interface GigabitEthernet 0/2
R2(config-if)#ip pim sparse-mode

The opposite side has been set up to dense-mode.

27

Hello Vadim

Yes, you are correct. I will let Rene know to make the correction.

In order to make the IGMP proxy feature function, you must have dense mode configured on the upstream router. If sparse mode was configured, and an IGMP join message was sent over the back channel, then the source based tree created would go through the back channel. So in order to be able to demonstrate this feature, dense mode had to be configured.

I hope this has been helpful!

Laz

28

Hey!
I have a question, i have to the the connect internet between R1 and R2 ?
All the story is dont work if i only have a undirectional connect between the routers(gig0/0/2)
Actually R2 tells R1 he wants multicast on gig 3?
It is true?
I hope you have a good week
Thank you very much

29

Hello Daniel

I’m not sure I understand the question. Can you give us some more information? It would also be helpful if you shared a diagram of your topology so that we can see the specific arrangement of your situation.

Thanks!

Laz