Unicast as Multicast

The unicast as multicast feature causes unicast searches in the filter data base to match on statically configured multicast entries using hardware forwarding. The unicast as multicast feature is used when a data stream originates from or is forwarded to a unicast address that then forwards it to multiple hosts, such as when using Network Load Balancing (NLB). When unicast as multicast is enabled on the device, a lookup is performed to determine if the unicast address has also been configured for multicast on the device. If a multicast address is found, packets are hardware forwarded out the configured VLAN and port(s) as defined in the static multicast configuration by extending the search phase of the Layer 2 lookup to match an unlearned destination MAC address against static multicast MAC entries. The unicast as multicast feature is configured by:

1. Using the set mac multicast command, in any command mode, to specify the MAC address to be treated as a multicast address, specifying the VLAN and egress port(s) to use
2. Using the set mac unicast-as-multicast command, in any command mode, to enable static unicast MAC addresses to be treated as multicast addresses on this device

The following command enables the unicast as multicast feature on this device:

System(rw)->set mac unicast-as-multicast enable
System(rw)->show mac unicast-as-multicast
Unicast as multicast: enabled
System(rw)->