hello-option lan-delay (IPv4)

Function

The hello-option lan-delay command sets the delay for transmitting Prune message on the shared network segment.

The undo hello-option lan-delay command restores the default delay.

Format

hello-option lan-delay interval

undo hello-option lan-delay

Parameters

Parameter	Description	Value
interval	Specifies the delay for transmitting Prune message on the shared network segment.	The value is an integer that ranges from 1 to 32767, in milliseconds (ms).

Views

PIM view

Default Level

2: Configuration level

Usage Guidelines

By default, the delay for transmitting Prune message on the shared network segment is 500 milliseconds.

Usage Scenario

Hello messages sent by FW s carry lan-delay and override-interval. The lan-delay parameter indicates the delay for transmitting messages in the LAN. When the values of lan-delay on all FW s on the same link are different, the maximum value of these values is used.

When one FW sends a Prune message to the upstream FW in the same network segment, if other FW still requests the multicast data, it needs to send a Join message to the upstream FW in the override-interval period.

The value of the Prune-Pending Timer (PPT) is obtained by the value of lan-delay plus the value of override-interval. PPT refers to the delay during which the current FW receives a Prune message from the downstream interface and performs the prune action. If the FW receives a Join message from the downstream interface in PPT, the FW cancels the prune action.

The hello-option lan-delay command can be used in the PIM view of a VPN instance to change the delay in transmitting Prune messages on all the interfaces in the VPN instance.

Prerequisites

The multicast routing-enable command has been run.

Configuration Impact

This command is cyclical in nature. That is, the latest command overwrites the previous one, and takes effect.

Precautions

This command is valid for PIM-SM and PIM-DM.

If the delay in transmitting Prune message is too short, the upstream FW will stop forwarding multicast packets before the downstream FW determines whether to override the Prune action or not. Exercise caution when running the hello-option lan-delay command.

This command functions in the same way as the pim hello-option lan-delay command in the interface view except for the views. By default, if no setting is done on the interface, the value set in the PIM view is used; otherwise, the value set in the interface view is used.

Example

# Set the delay for transmitting Prune message on the shared network segment to 200 ms.

<sysname> system-view
[sysname] multicast routing-enable
[sysname] pim
[sysname-pim] hello-option lan-delay 200