Couldn't ping the multicast address when I have the subinterfaces

[paheeradan.nagulan]

Experts,

Need your pick your brain on this issue. So I have 3 routers(iosv-3, iosv6 and iosv4) and a layer 2 switch(iol-l2-1). I'm using iosv-4 router as a multicast receiver by using the command ip igmp join-group 239.1.1.1. My goal is to ping 239.1.1.1 from iosv-3. I can ping the iosv-4 from iosv-3 using the unicast address but not with the multicast address.

At this time, iosv-6 has a sub interface of gi0/1.2  where the iosv-4 is in the vlan 2. When I don't have the sub interface, just the physical interface , i can ping the multicast address but not when I have the sub interface though. When I did the packet capture, i see the ICMP packets from iosv-3 to iosv-6. But I don't packets leaving from iosv-6 to the iosv-4.

Is there any command I have to enable when I use the sub interfaces?

Here is the "show ip mroute" on the iosv-6 router.

Here is the ip config on the iosv-6 router

Config on the iosv-4

Config on the iosv-3

[M02@rt37]

Hello @paheeradan.nagulan 

Since you are using pim sparse-mode, where is your rendez-vous point on your topology ? Configured on each routers also ?

[paheeradan.nagulan]

The rp address is the loopback of isov-6 router. I made sure that iosv-3 can ping that ip address.

Here is the output from iosv-3

[M02@rt37]

Ok @paheeradan.nagulan 

Add ip pim sparse-mode command on iosv-4 under interface Gi0/0 interface

interface GigabitEthernet0/0
ip address 2.0.0.1 255.255.0.0
ip pim sparse-mode
ip igmp join-group 239.1.1.1

Ensure that IGMP snooping is configured on L2 switch too

Esure that ip pim sparse-mode command is also configured on iosv-6 interface Gi0/1

Ensure that iosv-4 has got default route towards 2.0.0.2

[M02@rt37]

Also ensure that Lo 3.3.3.3 has got ip pim sparse-mode command too...

That should suceed after that:

[wajidhassan]

Hey there—when you move your multicast VLAN onto a router sub-interface you have to remember that multicast isn’t on by default the way unicast is

Here’s what you need to do:

Enable multicast routing globally so the router will forward multicast traffic:

iosv-6(config)# ip multicast-routing

Configure your VLAN 2 sub-interface for multicast:

iosv-6(config)# interface GigabitEthernet0/1.2
iosv-6(config-if)# encapsulation dot1Q 2
iosv-6(config-if)# ip address 2.0.0.2 255.0.0.0
iosv-6(config-if)# ip pim sparse-mode

This tags the interface for VLAN 2, assigns an IP, and enables PIM sparse-mode.

Verify or adjust IGMP snooping on your switch:

• If IGMP snooping is enabled, there must be an active querier on VLAN 2 (your iosv-6 router can serve as the querier).
• If you don’t have a querier, disable IGMP snooping so join messages are flooded to the router.

After that, you can confirm everything is working by running:

show ip mroute

You should see your multicast group entries, and you’ll be able to ping 239.1.1.1 from iosv-3 through iosv-6 to iosv-4.

Hope that helps—feel free to give it a try and let me know how it goes.

[paheeradan.nagulan]

Hi @wajidhassan ,

I added those config and still not able to ping across.

Here is the config on iosv-6

On the switch, the router interface is acting as the querier for the vlan 2.

After pinging from iosv-3 to iosv4(239.1.1.1), Here is the show ip mroute on the iosv-6

I see "SPF" flags for the entry ( *, 239.1.1.1). Is that supposed to be like that?

[M02@rt37]

@paheeradan.nagulan 

yes for L2 Switch!

On iosv-6 shluld be SJCL flag ! 

On L2 switch do you configured ip multicast-routing command ?

[paheeradan.nagulan]

Not sure why I am seeing SPF flag then!!!! Regarding the l2 switch, since it's a layer 2 . do you think I need to enable multicast routing on that?

[M02@rt37]

ip igmp snooping is activated on your L2 Switch ?

[paheeradan.nagulan]

Yes, igmp snooping enabled on the switch. iosv-4 can ping the iosv-3 device.

[M02@rt37]

hello @paheeradan.nagulan 

please provide the output of that command on iosv-3, iosv-4 and iosv-6

#show ip pim tunnel

Thanks a lot.

[paheeradan.nagulan]

Hi M02@rt37,

Here is the output on IOSV-3

Output on IOSV-6

On Iosv-4, I just added the config "ip igmp join-group 239.1.1.1"(Make it a multicast receiver) So there is no pim tunnel on that! isov-4 can ping 3.3.3.3.

[M02@rt37]

Thanks @paheeradan.nagulan 

OK for iosv-4 but it still is a router, so add ip multicast-routing command under config terminal and ip pim sparse-mode on Gig0/0

[paheeradan.nagulan]

I added the config.

Still I couldn't ping the multicast address of 239.1.1.2 from iosv-3