set multicast forwarding-table super-mode

Usage Scenario

After Layer 3 multicast is enabled, the common specification mode is used for multicast forwarding by default. This mode can meet requirements of most multicast service scenarios. In some large-scale multicast applications, a network has a large number of multicast sources to provide many channels for multicast users. In these applications, the number of multicast entries may exceed the default limit defined on a multicast device. When this occurs, some multicast entries cannot be generated. As a result, some users cannot receive the multicast data they request.

The set multicast forwarding-table super-mode command configures the high specification mode to increase the number of entries used for multicast forwarding. In high specification mode, the number of multicast entries supported by the switch is much larger than the default limit on the number of multicast entries. This mode maximizes a device's capability to support large-scale multicast applications.

Precautions

After you run this command:

• Restart the switch for the configuration to take effect.
• The default value of the IGMP general query interval changes from 60s to 120s. You can set the IGMP general query interval using the igmp timer query or timer query (IGMP view) command.
• The default value of the IGMP robustness variable changes from 2 to 3. You can set the robustness variable using the igmp robust-count or robust-count (IGMP view) command.
• The default value of the other querier present interval changes from 125s to 245s. You can set the other querier present interval using the igmp timer other-querier-present or timer other-querier-present (IGMP view) command.
• The default value of the MLD robustness variable changes from 2 to 3. You can set the robustness variable using the mld robust-count or robust-count (MLD view) command.
• The default interval for sending PIM-DM State-Refresh messages changes from 60s to 255s. On an IPv4 multicast network, run the state-refresh-interval (IPv4) command to set the interval for sending PIM-DM State-Refresh messages. On an IPv6 network, run the state-refresh-interval (IPv6) command to set the interval for sending PIM-DM State-Refresh messages.
• The default interval for sending PIM Join-Prune messages changes from 210s to 300s. On an IPv4 multicast network, run the holdtime join-prune (IPv4) or pim holdtime join-prune command to set the interval for sending PIM Join-Prune messages. On an IPv6 network, run the holdtime join-prune (IPv6) or pim ipv6 holdtime join-prune command to set the interval for sending PIM Join-Prune messages.
• Run the car command to change the rate limit for IGMP/MLD messages sent to the CPU according to the actual situations of multicast services.
• More system resources are consumed in the high specification mode. If the number of multicast protocol packets sent to the switch increases sharply in a short time, the CPU usage of the switch becomes high.
• It is recommended that you set the same general query interval on all the IGMP/MLD-enabled interfaces of a switch. For an IGMP-enabled interface, run the igmp timer query command in the interface view to set the general query interval. For an MLD-enabled interface, run the mld timer query command in the interface view to set the general query interval. This configuration prevents IGMP/MLD-enabled interfaces from sending Query messages at the same time, so that the switch does not have to process a large number of Report messages in a short time, which could cause a high CPU usage.
• In a stack, if member interfaces of an Eth-trunk interface are located on member switches that support different numbers of multicast forwarding entries, the maximum number of multicast forwarding entries supported by the Eth-Trunk interface depends on the member switch that supports the fewest multicast forwarding entries. Multicast forwarding entries supported by an Eth-Trunk interface meet either of the following conditions:
  • The outbound interface of the multicast forwarding entries is the Eth-Trunk interface that has been switched to the Layer 3 mode using the undo portswitch command.
  • The Eth-Trunk interface belongs to the VLANs corresponding to the VLANIF interfaces of the multicast forwarding entries.