BridgeTech VB20 User Manual page 253

As we have seen, there is no sure way to distinguish between UDP packet-loss and loss
in the underlying TS packets. One way to deal with the situation is to have a probe
doing zero readings close to the signal source before the network can introduce UDP
packet loss.
Thresholds
It is useful to configure individual threshold settings for IAT for each stream unless
they are fixed at the same bit-rate. Streams that are being monitored by several
probes should have equal Ethernet thresholds configured on each probe to make it
easy to compare measurements for a stream across several probes.
As a rule of thumb the IAT warning threshold could be set to 50% above the max IAT
value observed over a considerable period of time, the last 24h or so. The IAT error
threshold could be set a little below the maximum jitter the system can tolerate –
usually limited by the STB jitter tolerance. STB manufacturers should be able to
provide information about how much jitter they can handle. Setting the Ethernet
warning-threshold too high results in a graph where almost all plots are close to the x-
axis and it becomes less useful to visually compare MediaWindow graphs.
For streams with TS/UDP mapping the default MLR threshold is set so that errors are
reported if the number of CC errors exceeds the number of TS packets in one UDP
frame (assumed to be 7).
PROBE USERS' MANUAL VERSION 5.0
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