Adjusting Assert Control Parameters

Pre-configuration Tasks

Before configuring assert control parameters, complete the following tasks:

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

Context

When multiple PIM devices on a network segment pass the Reverse Path Forwarding (RPF) check and forward multicast data to this network segment, assert election is required. When a device receives multicast data through a downstream interface, it knows that other upstream devices exist on this network segment. The device then sends an Assert message to participate in the election of the unique upstream device.

PIM devices that fail the assert election disable their downstream interfaces from forwarding multicast data to this network segment. The assert loser state lasts for a period, which is called the holdtime of Assert messages. After the assert state timer times out, the devices that lost the Assert election restore pruned interfaces to the forwarding state to trigger a new round of Assert election.

The holdtime of Assert messages 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 holdtime of Assert messages is 180s.

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 holdtime assert interval
  The holdtime of Assert messages is configured.
  
  By default, the holdtime of Assert messages is 180 seconds.
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 holdtime assert interval
  The period for holding the Assert state is configured.

Verifying the Configuration

After assert control parameters are configured, you can check information about the PIM interface, PIM neighbors, and PIM routing table using the following commands:

Run the display pim [ vpn-instance vpn-instance-name | all-instance ] interface [ interface-type interface-number | up | down ] [ verbose ] command to check PIM information on an interface.
Run the display pim [ vpn-instance vpn-instance-name | all-instance ] neighbor [ neighbor-address | interface interface-type interface-number | verbose ] ^* command to check information about PIM neighbors.
Run the following commands to check 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 } ] ^*