Example for Configuring MLD Snooping

Networking Requirements

In Figure 1, the router is connected to user hosts through the Layer 2 switch on an IPv6 network. The multicast source sends data to multicast groups FF16::1 through FF16::5, but HostA, HostB, and HostC only want to receive date of multicast groups FF16::1 through FF16::3.

Figure 1 Network diagram for MLD snooping configuration

Configuration Roadmap

To meet the requirement, basic MLD snooping functions and multicast group policy need to be configured on the switch. The configuration roadmap is as follows:

Create a VLAN and add the interface to the VLAN.
Enable MLD snooping globally and in the VLAN.
Configure a multicast group policy in the VLAN.

Procedure

Create a VLAN and add interfaces to the VLAN.

<HUAWEI> system-view
[HUAWEI] sysname Switch
[Switch] vlan 10
[Switch-vlan10] quit
[Switch] interface gigabitethernet 0/0/1
[Switch-GigabitEthernet0/0/1] port link-type hybrid
[Switch-GigabitEthernet0/0/1] port hybrid pvid vlan 10
[Switch-GigabitEthernet0/0/1] port hybrid untagged vlan 10
[Switch-GigabitEthernet0/0/1] quit
[Switch] interface gigabitethernet 0/0/2
[Switch-GigabitEthernet0/0/2] port link-type hybrid
[Switch-GigabitEthernet0/0/2] port hybrid pvid vlan 10
[Switch-GigabitEthernet0/0/2] port hybrid untagged vlan 10
[Switch-GigabitEthernet0/0/2] quit
[Switch] interface gigabitethernet 0/0/3
[Switch-GigabitEthernet0/0/3] port link-type hybrid
[Switch-GigabitEthernet0/0/3] port hybrid pvid vlan 10
[Switch-GigabitEthernet0/0/3] port hybrid untagged vlan 10
[Switch-GigabitEthernet0/0/3] quit

Enable MLD snooping.
# Enable MLD snooping globally.
```
[Switch] mld-snooping enable
```
# Enable MLD snooping in VLAN 10.
```
[Switch] vlan 10
[Switch-vlan10] mld-snooping enable
[Switch-vlan10] quit
```
After the configuration is complete, the switch can generate Layer 2 multicast forwarding entries by listening to MLD messages. Ensure that the general query interval configured on the switch is the same as that on the upstream Layer 3 multicast device (router). Otherwise, some Layer 2 multicast forwarding entries may be aged out incorrectly, causing multicast traffic interruption. If the default general query interval of the switch is different from that of the router, run the mld-snooping query-interval query-interval command in VLAN 10 to change the general query interval on the switch.

Configure and apply a multicast group policy.

# Configure a multicast group policy.

[Switch] acl ipv6 2000
[Switch-acl6-basic-2000] rule permit source ff16::1 128
[Switch-acl6-basic-2000] rule permit source ff16::2 128
[Switch-acl6-basic-2000] rule permit source ff16::3 128
[Switch-acl6-basic-2000] quit

# Apply the multicast policy in VLAN 10.

[Switch] vlan 10
[Switch-vlan10] mld-snooping group-policy 2000
[Switch-vlan10] quit

Verify the configuration.

# Check the interface on the Switch.

[Switch] display mld-snooping port-info vlan 10
--------------------------------------------------------------------------------
                             (Source, Group)  Port                          Flag
                             Flag: S:Static    D:Dynamic
--------------------------------------------------------------------------------
VLAN 10, 3 Entry(s)                                                           
                     (*, ff16:0:0:0:0:0:0:1)  GE0/0/1                      -D-
                                              GE0/0/2                      -D-
                                                          2 port(s)
                     (*, ff16:0:0:0:0:0:0:2)  GE0/0/1                      -D-
                                              GE0/0/2                      -D-
                                                          2 port(s)
                     (*, ff16:0:0:0:0:0:0:3)  GE0/0/1                      -D-
                                              GE0/0/2                      -D-
                                                          2 port(s)
--------------------------------------------------------------------------------

The command output shows that GE0/0/1 and GE0/0/2 on the Switch have joined groups FF16::1 through FF16::3.

# Check the Layer 2 forwarding table on the Switch.

[Switch] display mld-snooping forwarding-table vlan 10
VLAN ID : 10, Forwarding Mode : IP                                      
------------------------------------------------------------------------
                     (Source, Group)    Interface               Out-Vlan
----------------------------------------------------------------------     
                         Router-port    GigabitEthernet0/0/3       10
               (*, ff16:0:0:0:0:0:0:1)  GigabitEthernet0/0/3       10
                                        GigabitEthernet0/0/1       10
                                        GigabitEthernet0/0/2       10
               (*, ff16:0:0:0:0:0:0:2)  GigabitEthernet0/0/3       10
                                        GigabitEthernet0/0/1       10
                                        GigabitEthernet0/0/2       10
               (*, ff16:0:0:0:0:0:0:3)  GigabitEthernet0/0/3       10
                                        GigabitEthernet0/0/1       10
                                        GigabitEthernet0/0/2       10
------------------------------------------------------------------------
Total Group(s) : 3

The command output shows that the forwarding table only entries of groups FF16::1 to FF16::3. Data of FF16::4 and FF16::5 is not forwarded to hosts.

Configuration Files

Switch configuration file

#
sysname Switch
#
vlan batch 10
#
mld-snooping enable
#
acl ipv6 number 2000
 rule 0 permit source FF16::1/128 
 rule 1 permit source FF16::2/128  
 rule 2 permit source FF16::3/128  
#
vlan 10
 mld-snooping enable
 mld-snooping group-policy 2000
#
interface GigabitEthernet0/0/1
 port link-type hybrid
 port hybrid pvid vlan 10
 port hybrid untagged vlan 10
#
interface GigabitEthernet0/0/2
 port link-type hybrid
 port hybrid pvid vlan 10
 port hybrid untagged vlan 10
#
interface GigabitEthernet0/0/3
 port link-type hybrid
 port hybrid pvid vlan 10
 port hybrid untagged vlan 10
#
return