Technical Description of TANDBERG 8000 with software version E3/B8
D12008 Rev. 11
30
4.2
Aggregation Standards
ISDN Aggregation
H.221
Frame Structure from 64(56
*
) kbps to 128 kbps
ISO 13871
BONDING, Mode 1 from 64(56
*
) kbps to 2 Mbps
4.2.1
BONDING
•
ISO 13871, BONDING Mode 1 for bit rates from 56 kbps up to 2 Mbps (1 to 30 channels).
•
The TANDBERG system can handle relative delay difference between B-channels of up to
0.5 second (i.e. to compensate for different routing of channels).
Example: Channel 1 is delayed 250 ms, channel 2 is delayed 500 ms and channel 3 is
delayed 330 ms. The
relative delay difference
is then (
max.
–
min.)
, thus in this case it would
be
500 ms – 250 ms = 250 ms (0.250 sec).
If delay difference is more than 0.5 seconds in the call, the TANDBERG system will display
‘Corrupted data received’ and try to resynchronize the call.
Note:
Delay difference
will vary depending on the different service providers involved in the
call.
The following are the standard bandwidths on H.320:
30ch – 24 – 23 – 18 – 12 – 8 – 6 – 5 – 4 – 3 – 2 – 1
4.2.2
H.221
•
For bit rates from 56 kbps up to 128 kbps (1 or 2 channels).
•
The maximum relative delay difference between the 2 B-channels is 0.6 second.
•
The system will only select H.221 if the far end does not support BONDING or when two
ISDN numbers are dialled.
Only 1 x 64 kbps H.221 support when External Network is used.
4.2.3
Encoding delay
H.320: The latency in a point-to-point call using TANDBERG systems on H.320 (ISDN) varies
between 160-250ms depending on the network performance.
H.323: The latency in a point-to-point call using TANDBERG systems on H.323 (IP) varies
between 120-160ms. (An additional 100ms have to be added for playout buffering).
NOTE, the total delay of a call will be as follows:
Encoding delay + Max. network delay + Decoding delay
