Terminology
Following is a brief description of terms and concepts used to describe the IGMP Proxy:
Upstream interface
Also referred to as the proxy interface. A proxy interface is an interface on which IGMP proxy service is configured. It is in the direction toward the root of the multicast forwarding tree. An upstream interface acts as a host running IGMP; therefore, it is also called host interface.
Downstream interface
An interface that is running IGMP and in the direction contrary to the root of the multicast forwarding tree. A downstream interface acts as a router running IGMP; therefore, it is also called router interface.
Member State
State of the associated group address and interface.
• Idle - Interface has not yet responded to a group membership query or general query for this group.
• Delay - Interface has responded to the latest group membership query or general query for this group.
IGMP-Proxy Configuration Steps
This section provides the configuration steps for configuring IGMP Proxy and example for a relevant scenario.
• Enable IP multicast on each router (see Enabling IP Multicast Routing)
• Enable IGMP Proxy service on the upstream interface.
• Enable IGMP mrouter configuration on the downstream interface.
• Enable IGMP proxy unsolicited report interval on the proxy interface. The proxy group membership reports are forwarded to the upstream router in this unsolicited report interval time. This is an optional parameter in which the default value of 1 sec is considered for forwarding proxy groups to upstream router.
Note: Configure IP addresses on all the interfaces used in the topology.
Unicast routing protocol should be configured in the PIM domain.
Topology
In this network topology, Router 1 acts as a proxying router to the upstream router Router 2 in which PIM domain is present. Also the source address is 172.31.1.52 and the group address is set to 224.0.1.3.
Note: Any PIM mode (PIM-SM,PIM-DM,PIM-SMDM) should be enabled on all the interfaces in the PIM domain.
Here in this example default value for unsolicited report interval is considered.
Figure 2-1: IGMP Proxy Topology
In this example, Routers 2 and 3 are running PIM and Router1 is the IGMP Proxying router.
• Host ends an IGMP membership report to Subnet 1.
• Downstream interface on Router1 received IGMP reports from host and updates the proxy interface.
• IGMP Proxying router (Router1) maintains the group membership information and forwards the received report to the upstream router (Router2).
• Source then sends a data packet for group.
• When the data packet reaches Router1, it forwards via the interface, eth2, because it has an IGMP join requested for Multicast traffic.
Last modified date: 07/14/2023