Multicast Channel Zapper

The Multicast Channel Zapper is a session type performing 'zapping' between a configurable set of multicast channels. This session type is intended to be used to measure/supervise the network's ability to process and handle IGMP join and leave requests.

The Zapper will loop through the channel list in a round-robin fashion, joining and leaving the multicast channels with a configurable zap interval to measure and report the following metrics for each channel:

• Join Delay (the time it takes to join the channel)
• Leave Delay (the time it takes to leave the channel)
• Channel Bandwidth (mean channel receive bandwidth)

Link Bandwidth (total link receive bandwidth)

The join-delay is defined to be the elapsed time from issuing the IGMP join request until arrival of the first packet in the multicast packet stream. The join operation will be said to fail if no packet has arrived when the time has come to issue the IGMP leave request.

The leave-delay is defined to be the elapsed time from issuing the IGMP leave request until reception of the last packet in the multicast packet stream. The leave operation will be said to fail if no packet could be stated to be the last packet, i.e. the packet stream was not stopped and was still arriving when it was time to join the channel again.

Moreover, the channel-bandwidth is reported for each channel, as well as the total link-bandwidth. The channel-bandwidth is determined by monitoring the number of packets/bytes received during the 'zap' interval. The total link-bandwidth is sampled at the time of issuing the IGMP join request.

Note: The link-bandwidth may be useful to examine to detect if multiple multicast channels are received in the same time, i.e. overlapped channels. This could happen if an IGMP leave request fails or the switch in use is (mis-)configured and forwards unwanted multicast traffic to the probe.