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# Multicast Streams
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To access the Multicast streams analysis use the menu entry "Statistics-\>Multicast Streams".
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To try out this dialog, a capture file containing MPEG2 Multicast streams can be found at [SampleCaptures/video\_multicast.cap.gz](uploads/__moin_import__/attachments/SampleCaptures/video_multicast.cap.gz)
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## What you can do with Multicast stream analysis?
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- Detect multicast streams
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- Measure how big the bursts inside video streams are (sliding window algorithm)
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- Measure how big the output buffer should be at a certain output speed (Leaky bucket algorithm)
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## Multicast streams dialog window
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![multicast\_streams.png](uploads/__moin_import__/attachments/Multicast_streams/multicast_streams.png "multicast_streams.png")
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## Procedure
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- the TAP system waits for UDP packets
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- every UDP packet is checked whether destination MAC address starts with "01:00:5E" (ethernet multicast address)
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- a new entry is created for every new multicast stream
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- based on sliding window algorythm max burst and max bandwidth is calculated
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- a counter shows how many times the number of packets in a burst was higher then limit specified
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- a leaky bucket algorithm calculates how big the output queue should be that no packet drop will occur
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- a counter shows how many times the demanded output queue was bigger then the one available
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- also for every stream total number of packets, pps, average BW, max BW are calculated
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- the same calculation is done for all multicast streams together
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## Parameters window
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Inside this window dialog it is possible to specify the burst interval, the alarm limits and output speeds
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![multicast\_parameters.png](uploads/__moin_import__/attachments/Multicast_streams/multicast_parameters.png "multicast_parameters.png")
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## Columns explanation
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- Max burst - the highest number of packets inside a sliding window time interval. The time interval can be specified inside the Set parameters window
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- Max Bw - same as the above one, only in Mbps instead of pps
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- Burst Alarms - how many times the bursts exceeded the limit set inside the Parameters dialog
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- Max buffer - how big the output queue should be that no packet will be dropped at specified output speed
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- Buff alarms - how many times this was not the case (the required buffer was higher than available one)
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---
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Imported from https://wiki.wireshark.org/Multicast_streams on 2020-08-11 23:17:03 UTC |