What does a switch do with Multicast traffic? Free software worth $200: https://goo.gl/613TUF
Ostinato – Network Traffic Generator Part 3. Easily create packets for testing in your GNS3 network.

Cisco IP Multicasting at layer 2 PDF: http://www.cisco.com/networkers/nw00/…

Ostinato is a packet crafter, network traffic generator and analyzer with a friendly GUI. Also a powerful Python API for network test automation. Craft and send packets of several streams with different protocols at different rates. Think of it as “Wireshark in Reverse”.