hello-option lan-delay (IPv4)

Function

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

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

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

Format

hello-option lan-delay interval

undo hello-option lan-delay

Parameters

Parameter	Description	Value
interval	Specifies the delay in 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 of public network instance or PIM view of VPN instance

Default Level

2: Configuration level

Usage Guidelines

Usage Scenario

Hello messages sent from switches carry lan-delay and override-interval values. The lan-delay parameter indicates the delay in transmitting messages in the LAN. If switches on the same link have different lan-delay values, the maximum value is used.

When a switch sends a Prune message to the upstream device in the same network segment, other switches that still request multicast data need to send a Join message to the upstream device within the override-interval period.

The value of the Prune-Pending Timer (PPT) is the sum of the lan-delay and override-interval values, and refers to the delay from the switch receiving a Prune message from the downstream interface to performing the prune action. If the switch receives a Join message from the downstream interface in PPT, the switch cancels the prune action.

Prerequisites

IP multicast routing has been enabled using the multicast routing-enable command.

Precautions

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

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

The hello-option lan-delay command has the same function as the pim hello-option lan-delay command in the interface view. By default, if the pim hello-option lan-delay command is not used, the value configured in the PIM view is used; otherwise, the value configured in the interface view is used.

Example

# Set the delay in transmitting Prune message on the shared network segment to 200 ms in PIM view of public network instance.

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