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CLI-based Configuration Guide - IP Multicast

AR120, AR150, AR160, AR200, AR1200, AR2200, AR3200, and AR3600 V200R007

This document describes the principles and configurations of IP multicast, and provides configuration examples.
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Configuring PIM GR

Configuring PIM GR

Pre-configuration Tasks

Before configuring PIM GR, complete the following tasks:

  • Configure a unicast routing protocol to ensure normal unicast routing on the network.
  • Enable PIM-SM.



Only the AR3200 series routers support PIM GR.

Multicast devices may need to perform active/standby switchovers in some scenarios, for example, when the multicast devices need to be upgraded or their control boards fail. After an active/standby switchover, the new active main control board deletes the forwarding entries on interface boards and re-learns the PIM routing table and multicast forwarding table. During this process, multicast traffic is interrupted.

PIM-SM supports the PIM graceful restart (GR) function on a device with dual main control boards. PIM GR ensures normal multicast data forwarding during active/standby switchover on the device.

After the PIM GR function is configured, the active main control board of the multicast device backs up PIM routing entries and Join/Prune information to be sent upstream to the standby main control board during active/standby switchover. The interface boards maintain forwarding entries. When an active/standby switchover occurs in the system, the multicast device can quickly send Join messages upstream to maintain the Join state of the upstream multicast device. Then, the PIM protocol sends Hello messages carrying Generation IDs to all neighbors with PIM-SM enabled. When a downstream multicast device finds that the Generation ID of its neighbor changes, it sends a Join/Prune message to the neighbor so that the neighbor can create new routing entries. This mechanism ensures nonstop forwarding of multicast data on the forwarding plane.

On a network using dynamic RP, when a DR receives a Hello message with a Generation ID different from the previous one, the DR sends a unicast Bootstrap message to the multicast device. The multicast device then restores the RP information from the Bootstrap message. If the multicast device cannot learn RP information from the Bootstrap message, it obtains RP information from the Join/Prune messages received from downstream devices and generates new multicast entries.

Default Configuration

The default PIM GR period is 120s.


  1. Run:


    The system view is displayed.

  2. Run:

    pim [ vpn-instance vpn-instance-name ]

    The PIM view is displayed.

  3. Run:


    PIM GR is enabled.

    By default, PIM GR is not enabled.

  4. (Optional) Run:

    graceful-restart period period

    The PIM GR period is configured.

    By default, the PIM GR period is 120 seconds.

Checking the Configuration

After PIM GR is configured, you can run the following commands to check entries in the PIM routing table.

  • display pim [ vpn-instance vpn-instance-name | all-instance ] routing-table [ group-address [ mask { group-mask-length | group-mask } ] | source-address [ mask { source-mask-length | source-mask } ] | incoming-interface { interface-type interface-number | register } | outgoing-interface { include | exclude | match } { interface-type interface-number | register | none } | mode { dm | sm | ssm } | flags flag-value | fsm ] * [ outgoing-interface-number [ number ] ]

  • display pim [ vpn-instance vpn-instance-name | all-instance ] routing-table brief [ group-address [ mask { group-mask-length | group-mask } ] | source-address [ mask { source-mask-length | source-mask } ] | incoming-interface { interface-type interface-number | register } ] *

Updated: 2019-06-12

Document ID: EDOC1000097181

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