Topology

This fabric runs ACI 5.3(1d). We have three VMs in the Layer-2 BD Net-108. One VM is connected to Leaf 102, and other VMs are behind a UCS-B in vPC. All VMs are in the subnet 10.229.108.0/24.

We use the following options for the BD:

• L2 Unknown Unicast: HW Proxy
• L3 Unknown Multicast Flooding: Optimized
• Multi Destination Flooding: Flood in BD

We use the default IGMP Snooping Policy:

It’s a L2 BD, we have Unicast Routing: disabled. We need a IGMP Querier. Here we will use: 10.229.108.254, which is an unused IP address in this subnet.

Linux Packages

To generate flow on VMs, we have two packages:

• smcroute
• iperf

In addition, we use tcpdump to capture packets. smcroute is used to join or leave the multicast group.

srv# smcroutectl join ens192 239.0.0.1
srv# smcroutectl leave ens192 239.0.0.1

We can check if the group is present with ip maddr

Example:

svr# ip maddr
1:	lo
	inet  224.0.0.1
	inet6 ff02::1
	inet6 ff01::1
2:	ens192
	[..]
	inet  239.0.0.1

To generate the flow (Sender) we used iperf.

srv# iperf -c 239.0.0.1 -u -T 10 -t 1800 -i 5

ACI verification

First we can check which querier are present in the leaf:

APIC01# fabric 102 show ip igmp snooping querier
----------------------------------------------------------------
 Node 102 (LEAF-102)
----------------------------------------------------------------
Vlan  IP Address       Version   Expires     Port
37    10.2.0.30        v3        00:01:01     Switch querier
74    10.229.108.254   v3        00:01:51     Switch querier

Here we use the querier 10.229.108.254, which is associated to the internal
vlan 74. We can see one group: 239.0.0.1 on the port Eth1/1.

APIC01# fabric 102  show ip igmp snooping groups vlan 74
----------------------------------------------------------------
 Node 102 (LEAF-102)
----------------------------------------------------------------
Type: S - Static, D - Dynamic, R - Router port, F - Fabricpath core port

Vlan  Group Address      Ver  Type  Port list
74    239.0.0.1          v3   D     Eth1/1

In addition, we can verify the IGMP Snooping parameters for that vlan.

APIC01# fabric 102  show ip igmp snooping vlan 74
----------------------------------------------------------------
 Node 102 (LEAF-102)
----------------------------------------------------------------
IGMP Snooping information for vlan 74
  IGMP snooping enabled
  Lookup mode: IP
  Optimised Multicast Flood (OMF) enabled
  IGMP querier present, address: 10.229.108.254, version: 3
  Querier interval: 125 secs
  Querier last member query interval: 1 secs
  Querier robustness: 2
  Switch-querier enabled, address 10.229.108.254/24, currently running
  IGMPv3 Explicit tracking enabled
  IGMPv2 Fast leave disabled
  IGMPv1/v2 Report suppression enabled
  IGMPv3 Report suppression enabled
  Link Local Groups suppression enabled
  Router port detection using PIM Hellos, IGMP Queries
  Number of router-ports: 0
  Number of groups: 2
  Multicast Routing disabled on VLAN
  Active ports:
    Eth1/1