IGMP/Snooping not working over NX-OSv

[FrankFried]

Happy Friday all,

Just as the title states, I've been having trouble getting IGMP through an NX-OSv in my lab. 

I've done a good bit of research into the subject but I can seem to find an answer as to why IGMP traffic isn't traversing the switch.

This is the bare bones setup I have going on right now. 

Everything is in VLAN 2 and can ping.
Router on the left has ip multicast-routing enabled, eth0/1 is setup as displayed.
NX-OS has igmp snooping enabled, IGMP querier setup as displayed on VLAN 2.

From everything I've read (for NX-OS IGMP snooping) this should work, but I'm clearly missing something. Any assistance is greatly appreciated! Happy to provide more detail.

 

[Enes Simnica]

hello @FrankFried. It sounds like your setup is close, but here are a few things to double-check:

Multicast Routing: Ensure the NX-OSv has multicast routing enabled (ip multicast-routing).
IGMP Snooping: Verify snooping is active and the querier is working with:
#show ip igmp snooping vlan 2
#show ip igmp snooping querier vlan 2
Also ensure PIM is enabled on the router’s interfaces and that IGMP joins are being forwarded correctly.
for sure let me know if more details are needed.

-Enes

[Giuseppe Larosa]

Hello @FrankFried ,

according to your network diagram all Nexus V ports eth2/1, eth2/2 and eth2/3 are L2 switchports in the same VLAN.

if so the role of IGMP querier is performed by multicast router IOU1 and IGMP snooping should classify the port towards it i.e. e2/3 as a multicast router port.

>> IGMP querier setup as displayed on VLAN 2.

don't set this on the Nexus box the role is performed by IOU1 router as I have explained above. The igmp querier command should be used only when no multicast router is connected to the VLAN. The reason is that this command does not allow an election . multicast routers that have ip pim sparse-dense mode confiigured take part in IGMP querier and PIM DR election for the segment. The command ip igmp querier is only to be used when no mrouter is present.

Hope to help

Giuseppe

[MHM Cisco World]

Change router port from sparse mode to dense mode 

Sparse mode work with RP only

MHM

[paul driver · Accepted solution]

Hello
Based on your topology = LAN Multicast - pim isn't required on the NK switch - all mc traffic is within a single vlan so no pim feature or routing is needed

Also snooping should be enabled by default  so if it isnt or you are not seeing any active ports in the vlan then it possible due to the simulation software you have and not the configuration.

For validation I ran a test on a N7K and it failed but on a N9K it work accordingly and for clarification i also ran it on a normal L2 switch and that worked also.

N9K layer 2
no pim/routing/mc routing enabled..- just lan multicast

Mc source 10.1.123.1 - 224.1.1.10
Mc receivers 10.1.123.2/3

N9K#
interface Ethernet1/1
description MC Receiver1
spanning-tree port type edge

interface Ethernet1/2
description MC Receiver2
spanning-tree port type edge

interface Ethernet1/3
description MC source
spanning-tree port type edge

N9K# sh feature | exclude disabled
Feature Name Instance State
-------------------- -------- --------

N9K# sh ip igmp snooping
Global IGMP Snooping Information:
IGMP Snooping enabled
Optimised Multicast Flood (OMF) enabled
IGMPv1/v2 Report Suppression enabled
IGMPv3 Report Suppression disabled
Link Local Groups Suppression enabled

IGMP Snooping information for vlan 1
IGMP snooping enabled
Lookup mode: IP
Optimised Multicast Flood (OMF) enabled
IGMP querier none
Switch-querier disabled
IGMPv3 Explicit tracking enabled
IGMPv2 Fast leave disabled
IGMPv1/v2 Report suppression enabled
IGMPv3 Report suppression disabled
Link Local Groups suppression enabled
Router port detection using PIM Hellos, IGMP Queries
Number of router-ports: 3
Number of groups: 0
VLAN vPC function disabled
Active ports:
Eth1/1 Eth1/2 Eth1/3 
Report Flooding: Disabled
Interfaces for Report Flooding: n/a
Use Group Address for Proxy Leaves: n

MC-receiver1#ping 224.1.1.10 repeat 3
Type escape sequence to abort.
Sending 3, 100-byte ICMP Echos to 224.1.1.10, timeout is 2 seconds:

Reply to request 0 from 10.1.123.1, 36 ms
Reply to request 1 from 10.1.123.1, 16 ms
Reply to request 2 from 10.1.123.1, 15 ms

MC-receiver2#ping 224.1.1.10 repeat 3
Type escape sequence to abort.
Sending 3, 100-byte ICMP Echos to 224.1.1.10, timeout is 2 seconds:

Reply to request 0 from 10.1.123.1, 34 ms
Reply to request 1 from 10.1.123.1, 15 ms
Reply to request 2 from 10.1.123.1, 16 ms

[FrankFried]

Hey Paul,

Thank you for the reply!

I agree with you about it being a problem with my simulation, I only read yesterday that there were issues with IGMP on the NX-OSv 7k version. I knew IGMP shouldn't be this hard!

This post covers exactly what you said Solved: Issue with routing protocol multicast packet transmission on SVI - Cisco Community

Much appreciated sir!

Very respectfully,
Frank

[MHM Cisco World]

share this please 

N9K# sh ip igmp snooping vlan 2  <<- let me check is it simulation or config issue 

MHM