Enabling MLD Snooping

Procedure

1. Run system-view

   The system view is displayed.

2. Run mld-snooping enable

   MLD snooping is enabled globally.

3. Run vlan vlan-id

   The VLAN view is displayed.

4. (Optional) Run l2-multicast forwarding-mode { ip | mac }

   The multicast forwarding mode in the VLAN is set to IP address-based or MAC address-based forwarding.

   By default, the IP address-based forwarding mode is used.

   

   • Set the multicast forwarding mode before enabling MLD snooping in the VLAN. The specified multicast forwarding mode takes effect only after MLD snooping is enabled.

   • A VLAN cannot be configured as a multicast VLAN after MAC address-based forwarding is configured in the VLAN using this command.

   • If the switch forwards multicast data packets based on MAC addresses, do not use a group address that maps to the same multicast MAC address as a multicast IP address reserved for a protocol. Otherwise, the protocol that uses the multicast IP address cannot run normally. For example, OSPF uses FF02::5 to send protocol packets. This multicast IP address maps to multicast MAC address 33-33-00-00-00-05. If multicast data packets are forwarded based on MAC addresses and use multicast IP address FF13::5 (also mapping to 33-33-00-00-00-05), the OSPF protocol cannot run normally.

   • For the S5720-EI, S5735-L, S5735-S, S5735-S-I, S5735S-L, S5735S-S, S5735S-L-M, S6720-EI, and S6720S-EI, if the VLANIF interface corresponding to a VLAN is bound to a VPN instance but MLD or IPv6 PIM is disabled on this interface, only the MAC address-based forwarding mode can be used in this VLAN. To use the IP address-based forwarding mode, configure this VLAN as a user VLAN and another VLAN as a multicast VLAN. In this way, multicast flows can be replicated to the user VLAN from the multicast VLAN.

5. (Optional) Run l2-multicast router-port-discard

   The switch is disabled from forwarding multicast data to router ports in a VLAN.

   

   Before disabling the switch from forwarding multicast data to router ports in a VLAN, disable MLD snooping in the VLAN. After setting the forwarding mode, enable MLD snooping in the VLAN for the configuration to take effect.

6. Run mld-snooping enable

   MLD snooping is enabled in the VLAN.

   To enable MLD snooping in multiple VLANs, run mld-snooping enable [ vlan { vlan-id1 [ to vlan-id2 ] } &<1-10> ] command in the system view.

   IGMP snooping cannot be used with N:1 (N > 1) VLAN mapping.