Multicast IGMP Snooping and PIM Design and Implementation

Use this design to configure Internet Group Management Protocol (IGMP) and Protocol Independent Multicast (PIM) in your fabric to improve multicast replication. IGMP snooping preserves bandwidth because multicast traffic is forwarded only on interfaces where there are IGMP listeners. For instance, every leaf device does not need to receive every instance of multicast traffic.

For an overview of multicast, see Multicast Optimizations.

In this design, we are using an external PIM gateway, which extends multicast beyond the data center, and is useful in DCI implementations.

The next sections show how to configure and verify multicast.

Configuring IGMP Snooping

In this design, we are using IGMP snooping to constrain multicast traffic in a broadcast domain to interested receivers and multicast devices.

To configure IGMP snooping:

Configure IGMP snooping on all VXLAN enabled VLANs on the leafs. The current implementation does not support IGMP snooping on selected VXLAN enabled VLANs.

Verifying IGMP Snooping

Enter the following CLI commands to verify IGMP snooping:

Verify the local IGMP snooping state on the leaf.

Verify that the leaf is advertising the EVPN Type 7 route where IGMP is snooped.

Verify that the leaf and its multihomed ESI peer device are both advertising the EVPN Type 6 route for the multicast group.

Configuring PIM

To configure PIM:

To configure inter-VNI multicast routing at the spine, create a routing instance for a tenant (a leaf device) named VRF-1. Configure the following in the routing instance:

Add the IRB interfaces to the leaf devices.
Enable PIM and configure the local address for this spine as the rendezvous point (RP).
Enable PIM on the IRB interfaces.

Spine 1:

Configure multicast routing on another spine. Configure a corresponding VRF routing instance for the same tenant as in step 6.

Add the IRB interfaces toward the leaf devices.
Enable PIM and configure the RP address on spine 1 as the static RP.
Enable PIM on the IRB interfaces.

Spine 2:

Verifying PIM

Enter the following commands to verify PIM:

On spine 1, check the PIM control plane on the RP, and verify that:

PIM joins are created from Type 6 routes that are generated by leaf devices.
IGMP reports are coming from non-IGMP snooping capable leaf devices.

On the spine that is configured as the PIM DR, verify the multicast forwarding state from the spine to the tenant VRF. To do so:

Enter show pim interfaces instance on all spines, and check the State column to see which IRB interface is a DR.

On the PIM DR, display the multicast forwarding state.

Multicast — Feature Summary

Table 1 provides a history of the features described in this section and their support within this reference design.

Table 1: Multicast Feature Summary
Hardware	IGMPv2 Snooping	EVPN Type 6 SMET Routes	Inter-VNI Multicast with PIM Gateway	PIM to External Rendezvous Point (From Border)
QFX5100¹	Not supported	Not supported	Not supported	Not supported
QFX5110-32Q, QFX5110-48S	18.1R3-S3	18.4R2	Not supported	Not supported
QFX5120-48Y	18.4R2	18.4R2	Not supported	Not supported
QFX5120-32C	19.1R2	19.1R2	Not supported	Not supported
QFX5200-32C¹, QFX5200-48Y¹	Not supported	Not supported	Not supported	Not supported
QFX10002-36Q/72Q, QFX10008, QFX10016	18.1R3-S3	18.4R2	18.1R3-S3	17.3R3-S1
QFX10002-60C²	20.2R2	20.2R2	20.2R2	20.2R2
MX204; MX240, MX480, MX960 with MPC7E; MX10003;	Not supported	Not supported	Not supported	Not supported

¹Make sure that IGMP snooping is not enabled on these QFX switches. If IGMP snooping is inadvertently enabled, these switches might process EVPN Type 6 routes that are reflected to them.

²The QFX10002-60C switch supports multicast at a lower scale than the QFX10002-36Q/72Q switches.

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