The following figure shows how a large number of elementary measurements are
represented by one bar in the graph.
IAT Before and After Router
Packet-loss that occurs before or inside a router will usually not be visible since the
queuing mechanism at the outgoing interface of the router will send out packets in an
orderly fashion. If however the packet-loss did occur after the router (due to line noise
for example) thus affect the timing between two neighbouring packets - effectively
doubling it – the packet loss will always affect the IAT component for CBR streams. For
VBR streams, that are jittery by default, the extra time gap may have no effect since
there may already be other larger gaps within the MediaWindow interval.
If a UDP packet goes missing after it has left the router it will visually affect both the
IAT and MLR for CBR streams. The pink line represents one elementary measurement.
For VBR streams a similar packet-loss will not necessarily affect the IAT graph even if
the time between two neighbouring packets doubles. The pink line represents the IAT
PROBE USERS' MANUAL VERSION 5.0
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