multicast load-splitting

Function

The multicast load-splitting command enables load splitting among multicast routes.

The undo multicast load-splitting command restores the default configuration.

By default, load splitting among multicast routes is disabled.

Format

multicast load-splitting { balance-preferred | stable-preferred | group | source | source-group }

undo multicast load-splitting

Parameters

Parameter	Description	Value
balance-preferred	Indicates balance-preferred load splitting. This policy is applicable to the scenario where hosts frequently join or leave groups, which requires automatic load adjustment.	-
stable-preferred	Indicates stable-preferred load splitting. This policy is applicable to stable multicast networking.	-
group	Indicates group address-based load splitting. This policy is applicable to the scenario of one source to multiple groups.	-
source	Indicates source address-based load splitting. This policy is applicable to the scenario of multiple sources to one group.	-
source-group	Indicates source and group addresses-based load splitting. This policy is applicable to the scenario of multiple sources to multiple groups.	-

Views

System view, VPN instance view, VPN IPv4 address family view

Default Level

2: Configuration level

Usage Guidelines

Usage Scenario

By default, if there are multiple equal-cost routes to a multicast source, the switch applies the following route selection rules during RPF check:

If the equal-cost routes are in the same routing table, for example, a unicast routing table, multicast static routing table, or MBGP routing table, the switch selects the route with the largest next-hop address as the RPF route.
If the equal-cost routes are in different routing tables, the switch selects the route with the highest preference. If the routes have the same preference, the switch selects the route with the longest mask length. If the routes have the same preference and mask length, the switch uses certain algorithm to select a route as the RPF route.

No matter which rule is used, the switch selects only one route as the RPF route. To enable multicast data to be forwarded through multiple paths, run the multicast load-splitting command to configure multicast load splitting. After multicast load splitting is configured, the switch uses the specified load splitting policy to distribute multicast data among multiple paths. This function improves quality of multicast forwarding.

Prerequisites

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

Follow-up Procedure

Because the forwarding capabilities of equal-cost routes are different from the actual load distribution situation on the equal-cost routes, even load splitting cannot meet network requirements in some scenarios. Then, you can run the multicast load-splitting weight command to configure the multicast load splitting weight on the interface to realize unbalanced load splitting.

Precautions

The five load splitting policies are mutually exclusive. It is recommended that you use a fixed load splitting policy based on the actual situation on your network. The balance-preferred or stable-preferred policy is preferred.

If PIM-DM is enabled in the current public network instance, the balance-preferred or stable-preferred policy cannot be used.

Example

# Configure group address-based load splitting.

<HUAWEI> system-view
[HUAWEI] multicast routing-enable
[HUAWEI] multicast load-splitting group