Understanding IGMP and Multicast

The Internet Group Management Protocol (IGMP) manages the membership of hosts and routers in multicast groups. IGMP is an integral part of IP and must be enabled on all routers and hosts that need to receive IP multicasts. IGMP is automatically enabled on all broadcast interfaces when you configure PIM or DVMRP.

By default, the device runs IGMPv2. However, you might still want to set the IGMP version explicitly on an interface, or all interfaces. Routers running different versions of IGMP negotiate the lowest common version of IGMP supported by hosts on their subnet. One host running IGMPv1 forces the device to use that version and lose features important to other hosts.

Related Topics

• Junos OS Feature Support Reference for SRX Series and J Series Devices
• Multicast Overview
• Example: Configuring IGMP for Multicast (CLI)
• IGMP Overview in the Junos Multicast Protocols Configuration Guide.