igmp proxy

Usage Scenario

In a simple tree topology, multicast switches directly connected to user network segments do not need to run any complicated multicast routing protocol (such as PIM). However, the upstream access devices have to manage many users because the multicast switches transparently transmit all IGMP messages from hosts. To reduce the load on the upstream device, configure IGMP proxy on the multicast switches. The multicast switches then collect and summarize Report/Leave messages received from downstream hosts before sending them to the upstream device. The multicast switches also maintain group memberships and forward multicast packets based on the group memberships. The upstream device considers the multicast switches as hosts.

IGMP proxy lacks a fault detection mechanism to trigger link switchover quickly. Therefore, multicast services will be interrupted for a long time when a link failure occurs. You can solve this problem by associating IGMP proxy with a network quality analysis (NQA) test instance. If you specify track nqa admin-name test-name in the command, IGMP proxy will be associated with the specified NQA test instance for end-to-end link status monitoring. When the NQA test instance detects a link failure on the active IGMP proxy interface, the switch with the IGMP proxy interface protection mode configured can trigger a switchover between the active/standby or active/active links quickly to minimize the communication interruption time.

• If an NQA test instance detects a primary link Down event, the IGMP proxy-capable device switches traffic from the primary link to the backup link or to the other primary link.
• If an NQA test instance detects a primary link Up event or if the NQA test instance is ineffective or deleted, the IGMP proxy-capable device switches traffic back from the backup link to the primary link or balances traffic between the primary links based on the computing result of the group hash algorithm.

Prerequisites

IP multicast routing has been enabled using the multicast routing-enable command.

Precautions

Only one active IGMP proxy interface and one backup IGMP proxy interface or two active IGMP proxy interfaces can be configured. Only the primary IGMP proxy interface can be associated with an NQA

IGMP proxy conflicts with the following features:

• PIM: If the pim sm or pim dm command has been configured on an interface, the igmp proxy command cannot be used on the interface. If the igmp proxy command is configured first, the pim sm or pim dm command cannot be used on the interface.
• IGMP: If the igmp enable command has been configured on an interface, the igmp proxy command cannot be used on the interface. If the igmp proxy command is configured first, the igmp enable command cannot be used on the interface.
• Static group: After a static group is configured on an interface, the igmp proxy command cannot be used on the interface. If the igmp proxy command has been configured, no static group can be configured on the interface.

• If two or more IGMP proxy interfaces have been configured on a device, the device's other interfaces cannot be configured as backup IGMP proxy interfaces.