spt-switch-threshold (IPv4)

Function

The spt-switch-threshold command sets the rate threshold of the multicast packets when the DR at the member side joins the SPT.

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

By default, the system performs SPT switchover on receiving the first multicast data packet through the RPT.

Format

spt-switch-threshold { traffic-rate | infinity } [ group-policy basic-acl-number [ order order-value ] ]

undo spt-switch-threshold [ traffic-rate | infinity ] [ group-policybasic-acl-number ]

Parameters

Parameter	Description	Value
traffic-rate	Specifies the threshold rate for the switchover from the RPT to the SPT. NOTE: Setting this parameter may affect operation of multicast services. You are advised to use the default triggering condition. That is, an SPT switchover is triggered immediately after the first multicast data packet is received from the RPT. The default triggering condition can reduce the number of multicast packets forwarded on the RPT.	The value is an integer that ranges from 1 to 4194304, in kbit/s.
infinity	Indicates that the SPT switchover is never triggered.	-
basic-acl-number	Specifies an entry of the group-policy list. It works with the multicast group that matches group-policy basic-acl-number to enable the threshold. basic-acl-number specifies the number of the basic ACL that defines the range of multicast groups.	If the parameter is not set, the threshold is applied to all multicast groups. The value ranges from 2000 to 2999.
order order-value	Adjusts the order of the ACLs in the group-policy list.	If a group matches multiple ACLs, the threshold is selected in the order specified by order-value. order-value specifies the updated number. It is an integer. The value is any value other than original one in the current group-policy list. If the parameter is not set, the order of the ACLs in the group-policy list does not change.

Views

PIM view of public network instance or PIM view of VPN instance

Default Level

2: Configuration level

Usage Guidelines

Usage Scenario

The source's DR encapsulates multicast packets in a Register message, and then transmits the unicast Register message to the RP. Then, the RP decapsulates the Register message and forwards the multicast packets to the receivers along the RPT. By default, when the RP or receiver's DR receives the first multicast packet, it initiates an SPT switchover to the source.

After the spt-switch-threshold command is executed on the receiver's DR, the receiver's DR periodically checks the forwarding rate of multicast packets. When the forwarding rate exceeds the threshold, the receiver's DR sends a Join messages to the source, triggering the SPT switchover.

Prerequisites

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

Precautions

This command is valid to all devices that may function as the DR at the member side, but is invalid to RPs.

This command is valid for only PIM-SM.

If this command is used several times for the same group, the first matching command takes effect.

Example

# In the PIM view of public network instance, set the traffic rate threshold to 4 kbit/s. If the transmission rate of packets from the source to the multicast group exceeds the threshold, the switch triggers an SPT switchover so that packets are forwarded along the SPT towards the source.

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

# In the public network instance, create a group-policy that uses ACL 2010, specify the infinity keyword in the command to ensure that an SPT switchover will never be triggered, and set the order of ACL 2010 in the group-policy to 1.

<HUAWEI> system-view
[HUAWEI] acl number 2010
[HUAWEI-acl-basic-2010] rule permit source 225.1.1.1 0
[HUAWEI-acl-basic-2010] quit
[HUAWEI] multicast routing-enable
[HUAWEI] pim
[HUAWEI-pim] spt-switch-threshold infinity group-policy 2010 order 1