Sencore VB2 Series User Manual

Imagine the following MPEG-2 Transport Stream being generated by an encoder. The TS contains two
PIDs (50 and 51) and the Continuity Counter (CC) values are continuous for each PID since there are no
packets missing.
PID: 50
CC: 12
PID: 51
CC: 1
PID: 50
CC: 13
PID: 51
CC: 2
PID: 50
CC: 14
PID: 51
CC: 3
PID: 50
CC: 15
PID: 51
CC: 4
...
PID: 50
CC: 0
PID: 51
CC: 5
PID: 50
CC: 1
PID: 51
CC: 6
PID: 50
CC: 2
PID: 51
CC: 7
PID: 50
CC: 3
PID: 51
CC: 8
PID: 50
CC: 4
PID: 51
CC: 9
PID: 50
CC: 5
PID: 51
CC: 10
PID: 50
CC: 6
PID: 51
CC: 11
PID: 50
CC: 7
PID: 51
CC: 12
PID: 50
CC: 8
PID: 51
CC: 13
PID: 50
CC: 9
PID: 51
CC: 14
PID: 50
CC: 10
PID: 51
CC: 15
...
When the Transport Stream reaches our imaginary head-end some packets (those with red frame) have
been lost (maybe due to a bad satellite connection). Our IP-Streamer packs 7 and 7 MPEG-2 TS packets
into each UDP-frame (mapping is 7TS/UDP) and the resulting frames may look like:
PID: 50
CC: 12
PID: 50
CC: 13
PID: 50
CC: 4
PID: 51
CC: 1
PID: 51
CC: 2
PID: 51
CC: 4
PID: 51
CC: 5
PID: 50
CC: 5
PID: 50
CC: 6
PID: 50
CC: 7
PID: 51
CC: 8
PID: 51
CC: 9
PID: 51
CC: 10
PID: 51
CC: 11
. . .
The probe’s response to this multicast is summarized in the following table:
Sequence
Effect
UDP packet #1 (7 MPEG2 TS packets):
PID 50: 12, 13, 14, 15
PID 51: 1, 2, 4, 5, 8
PID 51 has 2 CC discontinuities of 2 (2 − > 4)
and 3 (5− >8)
Monitoring page: CCerr:+2
UDP packet #2 (7 MPEG2 TS packets):
PID 50: 4, 5, 6, 7
PID 51: 9, 10, 11
PID 50 has 1 CC discontinuity of 6 (13− >4)
Monitoring page: CCerr:+1
If no more CC-errors for at least 1 second
Alarms & events:
CC skips:9 discontinuities:3
Depending on the thresholds you may also get: MLR >=
warning-threshold (9 >= 1)
There were 9 TS packets missing (with red frame) and the alarm reflects this.
254 VB2xx GigE User’s Manual version 5.4

Sencore VB2 Series Specifications

General

Brand	Sencore
Model	VB2 Series
Category	Network Hardware
Language	English