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Multicast is when someone sends a single set of data packets across a network to multiple selected users at the same time. Multicast is subscription-based: Computers that want to receive multicast traffic use ICMP messages to let routers know which multicast addresses they want to subscribe to. The routers are then able to calculate which multicast messages they need to send to receivers on their different interfaces. A packet is considered a multicast packet if the destination IP address is in the range 224.0.0.0 to 239.255.255.255.

PerformanceGuard can collect statistics about IP multicast UDP messages. Multicast messages are one-way, that is the sender doesn't get any response from receivers. Therefore, PerformanceGuard doesn't measure:

• Multicast response times
  
  
• Multicast network transmission times

but it does measure:

• The number of packets sent and received as multicast messages
  
  
• The number of bytes sent and received as multicast messages

The following is all you need in order to measure multicast traffic and view the measurements in graph or table formats:

• Make sure that PerformanceGuard agents collect data about multicast traffic: Select ADMINISTRATION > Agent Configuration > Configurations. Then click the Edit link next to the required agent configuration group(s). Scroll down to the Network Report section and verify that Enable Multicast UDP Reports is selected.
  
  
• If required, set up multicast groups: Select ADMINISTRATION > Server > Multicast.

• Now you can begin to view data about multicast traffic on the Multicast Traffic graph and Multicast Activity overview.