Using Multicast, a source can send a single copy of data to a single multicast address, which is then distributed to a group or recipients.

NSX uses two multicast routing protocols: Internet Group Management Protocol (IGMPv2) and Protocol Independent Multicast (PIM). PIM sparse mode is supported (PIM-SM). PIM is used on ESGs, but not on the DLR.

Attention: During vMotion of virtual machines that are receivers of multicast, a 1–2 second multicast traffic loss can occur.
For more information about multicast support in NSX, see Multicast Routing Support, Limitations, and Topology.

If an ESG is at 6.4.4 or earlier, PIM is supported on a single uplink interface of the Edge. Starting in NSX Data Center 6.4.5, PIM is supported on two uplink interfaces of the ESG.

Starting in NSX 6.4.7, PIM is also supported on one GRE virtual tunnel interface (VTI) per ESG. PIM can be enabled on a maximum of two uplink interfaces of the ESG or one GRE tunnel interface. However, you cannot enable PIM simultaneously on the GRE virtual tunnel interface and edge uplink interfaces.

To enable PIM on a GRE tunnel interface, you must first configure GRE tunnels on the ESG by using the NSX APIs. For more information about configuring GRE tunnels, see the NSX API Guide. After configuring GRE tunnels on the ESG, you can view the list of GRE tunnels in the vSphere Client UI.

The GRE virtual tunnel interface can be configured with either IPv4 address, or IPv6 address, or both. However, to enable PIM on the GRE tunnel interface, the tunnel interface must have an IPv4 address. If the GRE virtual tunnel interface is configured with only an IPv6 address, this GRE tunnel interface cannot be enabled as a PIM interface.

When PIM is enabled on a GRE tunnel interface, static routes must be added with the IP address of the GRE virtual tunnel endpoint as the next hop IP address. Static routes are required to reach the multicast sources, receivers, and rendezvous point (RP) outside the NSX network.


  1. In the vSphere Client, navigate to Networking & Security > NSX Edges.
  2. Click an NSX Edge.
  3. Click Routing > Multicast.
  4. Enable multicast.
    Version Procedure
    NSX 6.4.2 to 6.4.4

    In Configuration, click the toggle switch to enable multicast.

    NSX 6.4.5 and later
    1. Next to Configuration, click Edit.
    2. In Status, click the toggle switch to enable multicast.
  5. Configure IGMP parameters. IGMP messages are used primarily by multicast hosts to signal their interest in joining a specific multicast group, and to begin receiving group traffic. IGMP Parameters configured on the DLR must match those configured on the ESG, and have to be configured globally for the ESG and the DLR.
    IGMP Parameter Description
    Query Optional. Configures the frequency at which the designated router sends IGMP host-query messages. The default is 30 seconds. Maximum value is 3,744 seconds.
    Query Max Response Time (sec) Optional. Sets the maximum amount of time that can elapse between when the querier router sends a host-query message and when it receives a response from a host. The default is 10 seconds. Maximum value is 25 seconds.
    Last Member Query Interval (sec)

    Optional. Configures the interval at which the router sends IGMP group-specific query messages. The default is 1 second. Maximum value is 25 seconds.

    Robustness Variable Optional. The default value is 2. Maximum value is 255.
  6. (Optional) Under PIM Sparse Mode Parameters (PIM-SM), enter the Static Rendezvous Point Address. The rendezvous point (RP) is the router in a multicast network domain that acts as the root of the multicast shared tree. Packets from the upstream source and join messages from the downstream routers “rendezvous” at this core router. RP can be configured statically and dynamically with use of a Bootstrap Router (BR). If a static RP is configured, it is applicable to all the multicast groups.

    An ESG cannot be the rendezvous point or Bootstrap Candidate Router. PIM-SM configuration is done at the PIM global configuration level per edge.

  7. Under Enabled Interfaces, click Configure Interfaces, and enable PIM on the interfaces.
    You can enable PIM on the following interfaces:
    • A maximum of two uplink interfaces of an ESG or on a single GRE virtual tunnel interface of an ESG, but not on both at the same time.
    • A single internal interface of an ESG.
  8. Click Publish for the changes to take effect.

What to do next

If you have enabled PIM on a GRE virtual tunnel interface, static routes are required to reach the multicast sources, receivers, and RP outside the NSX network. You must configure static routes with the IP address of the GRE virtual tunnel endpoint as the next hop IP address.

For detailed information about configuring static routes, see Add a Static Route.