Configuring the DR Priority

Context

The shared network segment where a multicast source or group member resides is usually connected to multiple PIM devices. PIM devices exchange Hello messages to elect a designated router (DR) on the network segment, which is the unique sender of multicast packets. The DR priorities carried in Hello messages are compared at first. The device with the highest DR priority wins (A larger value indicates a higher priority). If PIM devices have the same DR priority or at least one PIM device does not support Hello messages carrying the DR priority, the PIM device with the largest IP address wins.

The DR priority can be configured globally or on an interface. If this parameter is configured in both the global PIM view and interface view, the configuration in the interface view takes effect.

Default Settings

The default DR priority is 1.

Procedure

Global configuration
1. Run system-view
  The system view is displayed.
2. Run pim [ vpn-instance vpn-instance-name | all-instance ]
  The PIM view is displayed.
3. Run hello-option dr-priority priority
  The priority for DR election is configured.
Configuration on an interface
1. Run system-view
  The system view is displayed.
2. Run interface interface-type interface-number
  The interface view is displayed.
3. (Optional) On an Ethernet interface, run undo portswitch
  The interface is switched to Layer 3 mode.
  
  By default, an Ethernet interface works in Layer 2 mode.
  
  Only the S5720-EI, S5720-HI, S5730-HI, S5731-H, S5731-S, S5731S-H, S5731S-S, S5732-H, S6720-EI, S6720-HI, S6720S-EI, S6730-H, S6730S-H, S6730-S, and S6730S-S support switching between Layer 2 and Layer 3 modes.
4. Run pim hello-option dr-priority priority
  The priority for DR election is configured.