Adjusting Assert Control Parameters

Pre-configuration Tasks

Before configuring assert control parameters, complete the following tasks:

Configure an IPv6 unicast routing protocol to ensure normal unicast routing on the network.
Enable IPv6 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 compete with other upstream devices to forward multicast data.

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

The default holdtime of Assert messages is 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 holdtime of Assert messages is configured.

Verifying the Configuration

After assert control parameters are configured, check information about the IPv6 PIM interface, statistics about IPv6 PIM control messages, 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 following commands in any view to check the number of sent and received IPv6 PIM control packets.
- display pim ipv6 control-message counters message-type { probe | register | register-stop | crp }
- display pim ipv6 control-message counters [ message-type { assert | graft | graft-ack | hello | join-prune | state-refresh | bsr } | interface interface-type interface-number ] ^*
Run the following commands to check the IPv6 PIM routing table.
- 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 ] ]
- 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 } ] ^*