hello-option lan-delay (VPN instance PIM view/PIM view of a public network instance)

Function

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

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

By default, the delay in transmitting Prune messages on a 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 from the time when the current router receives a Prune message from a downstream router to the time when the current router performs the prune action.	The value is an integer that ranges from 1 to 32767, in milliseconds (ms).

Parameter

Description

Value

interval

Specifies the delay from the time when the current router receives a Prune message from a downstream router to the time when the current router performs the prune action.

The value is an integer that ranges from 1 to 32767, in milliseconds (ms).

Views

VPN instance PIM view, PIM view of a public network instance

Default Level

2: Configuration level

Task Name and Operations

Task Name	Operations
pim	write

Usage Guidelines

Usage Scenario

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

If a router receives a Prune message from the upstream interface, it indicates that other downstream routers still exist in the LAN. If the router still needs to receive multicast data, it must send a Join message to the upstream interface 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 router receives a Prune message from the downstream interface and performs the prune action. If the router receives a Join message from the downstream interface in PPT, the router cancels the prune action.

Prerequisites

The multicast routing-enable command is run in the public network instance view or VPN instance view.

Configuration Impact

If the hello-option lan-delay command is run more than once, the latest configuration overrides the previous one.

Precautions

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

Example

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

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