spt-switch-threshold (VPN instance PIM view/PIM view of a public network instance)

Function

The spt-switch-threshold command sets a multicast data forwarding rate threshold at which a receiver's designated router (DR) performs a switchover from the rendezvous point tree (RPT) to the shortest path tree (SPT).

The undo spt-switch-threshold command restores the default value.

By default, a receiver's DR performs a switchover from the RPT to the SPT immediately after receiving the first multicast data packet.

Format

spt-switch-threshold traffic-rate

undo spt-switch-threshold [ traffic-rate ]

Parameters

Parameter	Description	Value
traffic-rate	Specifies a multicast data forwarding rate threshold at which a receiver's DR performs a switchover between the RPT and the SPT. Multicast data forwarding rate = Number of multicast data bytes received in a period/Duration of the period (the duration can be specified using the timer spt-switch command). When the multicast data forwarding rate exceeds traffic-rate, the system performs a switchover from the RPT to the SPT. After the switchover is complete, the system does not switch traffic back to the RPT any more.	The value is an integer ranging from 1 to 4194304, in kbit/s.

Parameter

Description

Value

traffic-rate

Specifies a multicast data forwarding rate threshold at which a receiver's DR performs a switchover between the RPT and the SPT.

Multicast data forwarding rate = Number of multicast data bytes received in a period/Duration of the period (the duration can be specified using the timer spt-switch command).

When the multicast data forwarding rate exceeds traffic-rate, the system performs a switchover from the RPT to the SPT. After the switchover is complete, the system does not switch traffic back to the RPT any more.

The value is an integer ranging from 1 to 4194304, in kbit/s.

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

In PIM-SM, a source's DR encapsulates multicast data packets in a Register message and sends the Register message to the rendezvous point (RP). The RP then transmits the multicast data along the RPT to receivers. The RP and the receiver's DR are responsible for checking the forwarding rate of multicast data packets.

If a rate threshold is configured on the receiver's DR, the receiver's DR sends a Join message to the source only it finds that the forwarding rate of multicast data packets exceeds the threshold and then triggers the switchover from the RPT to the SPT. To set such a rate threshold, run the spt-switch-threshold command.

This command takes effect on the Router that functions as the receiver's DR, but does not take effect on the RP.

Prerequisites

The multicast routing function has been enabled using the multicast routing-enable command in the public network instance view or VPN instance view.

Precautions

NOTE:

If the spt-switch-threshold command is run more than once for one multicast group, the first command that the multicast group matches takes effect.

Example

# In the public network instance, set the multicast data forwarding rate threshold to 4 kbit/s. If the rate of multicast data packets transmitted from the source to the multicast exceeds the threshold, the Router triggers the switchover from the RPT to the SPT.

<HUAWEI> system-view
[~HUAWEI] multicast routing-enable
[*HUAWEI] pim
[*HUAWEI-pim] spt-switch-threshold 4