Smart multicast is a new level of efficiency for converged networks.
The Cisco Catalyst 3750 series supports smart multicast, which has only one copy of the multicast in the stack interconnect, thereby conserving bandwidth.
With Cisco StackWise technology, the Cisco Catalyst 3750 series offers greater efficiency for multicast applications, such as video. Each data packet is put onto the backplane only once, which provides more effective support for more data streams. This provides superior quality of service across the stack and at wire speed.
Each data packet has a 24-byte header with an activity list for the packet as well as a QoS designator. The activity list specifies the port destination or destinations and what should be done with the packet.
In the case of multicast, the master switch identifies which of the ports should receive a copy of the packets and adds a destination index for each port. One copy of the packet is put on the stack interconnect. Each switch port that owns one of the destination index addresses then copies this packet.
This creates a much more efficient mechanism for the stack to receive and manage multicast information.