2. Appendix: Monitoring Practices
This Appendix summarises a few useful monitoring practices.
RTP Monitoring
When running video inside an RTP wrapper it is possible to exactly deduce the number
of dropped IP frames due to network issues. This is possible as a result of the 16-bit
sequence counter inside the RTP header. When the protocol mapping is nTS/RTP the
RTP parameters
RTPdrop
,
RTPdup
,
RTPooo
and
RTPlag
will be updated and the
corresponding alarms
Packet drops:N
,
Duplicate packets:N
and
Out of order
packets(lag:N)
are fired (if not switched off).
Note that the probe will perform out-of-order corrections before RTP packet loss
analysis is performed.
Example of RTP sequences and their effects on monitoring:
Sequence Effect
..., 10, 11, 12, 13, 14, 17, 18, 19, ...
2 dropped packets (15-16)
Monitoring page:
R2
Alarms & events:
RTP Packet drop: 2
..., 10, 12, 13, 16, 17, 18, 19, ...
1 and 2 dropped packets (11, 14-15)
Monitoring page:
R3
Alarms & events:
RTP Packet drop: 3
..., 10, 11, 15, 12, 14, 16, 18, 19, ...
2 dropped packets (13, 17)
1 out of order packets of order 3
(15
12)
Monitoring page:
R2
Monitoring page:
1
Monitoring page:
RTPlag: 3
(at least)
Alarms & events:
RTP Packet drops: 2
Alarms & events:
RTP out of order
packets (lag:3)
Default Monitoring
When the protocol mapping is nTS/UDP, meaning there is no RTP information in the
multicast stream, there is no easy way to isolate and register network-induced errors.
Assumptions can be done by performing continuity counter analysis for the content of
each received UDP-frame on the fly. The probe will note CC-errors (
CCerr
) and
generate corresponding alarms (
CC skips:N
).
PROBE USERS' MANUAL VERSION 5.0
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-
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