Multicast Streams

To access the Multicast streams analysis use the menu entry "Statistics->Multicast Streams".

To try out this dialog, a capture file containing MPEG2 Multicast streams can be found at SampleCaptures/video_multicast.cap.gz

What you can do with Multicast stream analysis

Detect multicast streams
Measure how big the bursts inside video streams are (sliding window algorithm)
Measure how big the output buffer should be at a certain output speed (Leaky bucket algorithm)

the TAP system waits for UDP packets
every UDP packet is checked whether destination MAC address starts with "01:00:5E" (ethernet multicast address)
a new entry is created for every new multicast stream
Based on the sliding window algorithm, max burst and max bandwidth are calculated
A counter shows how many times the number of packets in a burst exceeded the specified limit
A leaky bucket algorithm calculates how large the output queue should be to prevent packet drops
A counter shows how many times the demanded output queue exceeded the available capacity
also for every stream total number of packets, pps, average BW, max BW are calculated
the same calculation is done for all multicast streams together

Inside this window dialog it is possible to specify the burst interval, the alarm limits and output speeds

Max burst - the highest number of packets inside a sliding window time interval. The time interval can be specified inside the Set parameters window
Max Bw - same as the above one, only in Mbps instead of pps
Burst Alarms - how many times the bursts exceeded the limit set inside the Parameters dialog
Max buffer - how big the output queue should be that no packet will be dropped at specified output speed
Buff alarms - how many times this was not the case (the required buffer was higher than available one)