Adjusting Assert Control Parameters

Pre-configuration Tasks

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 is configured globally or on an interface. If you configure the holdtime of Assert messages in the global PIM-IPv6 view and in the interface view simultaneously, the configuration in the interface view takes effect.

Default Settings

Table 1 lists default settings of assert control parameters.

**Table 1** Default settings of assert control parameters
Parameter	Default Setting
Period for holding the Assert state	180s

Procedure

Global configuration
1. Run system-view
  The system view is displayed.
2. Run pim-ipv6
  The PIM-IPv6 view is displayed.
3. Run holdtime assert interval
  The holdtime of Assert messages 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 ipv6 holdtime assert interval
  The period for holding the Assert state is configured.

Verifying the Configuration

After assert control parameters are configured, check information about the IPv6 PIM interface, IPv6 PIM neighbor, and IPv6 PIM routing table using the following commands:

Run the display pim ipv6 interface [ interface-type interface-number | up | down ] [ verbose ] command to check IPv6 PIM information on an interface.
Run the display pim ipv6 control-message counters [ message-type { assert | graft | graft-ack | hello | join-prune | state-refresh | bsr } | interface interface-type interface-number ] ^* command to check information about IPv6 PIM neighbors.
Run the following commands to check the IPv6 PIM routing table:
- Run the display pim ipv6 routing-table [ ipv6-source-address [ mask mask-length ] | ipv6-group-address [ mask mask-length ] | flags flag-value | fsm | incoming-interface { interface-type interface-number | register } | mode { dm | sm | ssm } | outgoing-interface { exclude | include | match } { interface-type interface-number | none | register } ] ^* [ outgoing-interface-number [ number ] ] command to check detailed information about the IPv6 PIM routing table.
- Run the display pim ipv6 routing-table brief [ ipv6-source-address [ mask mask-length ] | ipv6-group-address [ mask mask-length ] | incoming-interface { interface-type interface-number | register } ] ^* command to check brief information about the IPv6 PIM routing table.