Dell PowerConnect 7048P Manual page 1186

Figure 42-38. Add SSM Range
3 Click the Add Default SSM Range check box to add the default SSM
Range. The default SSM Range is 232.0.0.0/8 for IPv4 multicast and
ff3x::/32 for IPv6 multicast.
4 Enter the SSM Group IP Address.
5 Enter the SSM Group Mask (IPv4) or SSM Prefix Length (IPv6).
6 Click Apply.
The new SSM Range is added, and the device is updated.
1186
Managing IPv4 and IPv6 Multicast