Configuring Multicast Load Splitting

Performing load splitting of multicast traffic according to different policies can optimize network traffic transmission in the scenario where multiple multicast data flows exist. You can choose to configure a balance-preferred or stable-preferred load splitting policy.

Prerequisites

Before configuring multicast load splitting, complete the following tasks:

Configuring a unicast routing protocol
Configuring basic multicast functions

Context

Configurations related to VPN instances are applicable only to the PE FW. When configuring load splitting among multicast routes for a VPN instance on a PE, perform the configuration in the VPN instance. In other cases, load splitting among multicast routes is configured in the public network instance.

The multicast load splitting function extends multicast routing rules, which does not fully depend on the Reverse Path Forwarding (RPF) check. If multiple equal-cost optimal routes exist over the network, they all can be used for multicast data forwarding and multicast traffic is load split among multiple equal-cost routes.

By default, load splitting is not performed.

Procedure

Public network instance
1. Access the system view.
  system-view
2. Configure multicast load splitting.
  multicast load-splitting { balance-preferred | stable-preferred | source | group | source-group }
  
  The parameters of the command are explained as follows:
  - balance-preferred: indicates balance-preferred load splitting. This policy is applicable to the scenario where hosts frequently join or leave the groups, which requires automatic load adjustment.
    
    If balance-preferred is specified, the FW automatically adjusts and balances the entries on the equal-cost routes when equal-cost routes are added or deleted, IPv4 multicast routing entries are deleted, or IPv4 load splitting weights on the interfaces are changed.
  - stable-preferred: indicates stable-preferred load splitting. This policy is applicable to the stable multicast networking.
    
    If stable-preferred is specified, the FW automatically adjusts and balances the entries when equal-cost routes are added or deleted; however, when IPv4 multicast routing entries are deleted or load splitting weights on the interfaces are changed, the FW does not automatically adjust the entries on the equal-cost routes.
  - 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 one group to multiple sources.
  - source-group: indicates source and group addresses-based load splitting. This policy is applicable to the scenario of multiple sources to multiple groups.
  It is recommended that you adopt a fixed IPv4 multicast load splitting policy based on the actual networking. It is recommended that you use the balance-preferred or stable-preferred policy.
  
  balance-preferred or stable-preferred cannot be configured on the interface enabled with PIM-DM.
  
  You can configure a multicast load splitting timer or a multicast load splitting weight only in a stable-preferred load splitting or balance-preferred load splitting scenario.
3. (Optional) Set a load splitting timer.
  multicast load-splitting-timer interval
VPN instance
1. Access the system view.
  system-view
2. Access the VPN instance view.
  ip vpn-instance vpn-instance-name
3. Enable the IPv4 address family for the VPN instance and access the VPN instance IPv4 address family view.
  ipv4-family
4. Configure multicast load splitting.
  multicast load-splitting { balance-preferred | stable-preferred | source | group | source-group }
  
  You can configure a multicast load splitting timer or a multicast load splitting weight only in a stable-preferred load splitting or balance-preferred load splitting scenario.
5. (Optional) Set a load splitting timer for the VPN IPv4 address family.
  multicast load-splitting-timer interval