Cisco Headend System Release 3.2 Maintenance Manual
Chapter 2 Optimize Your System Performance for Downloads and Staging
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4024836 Rev D
Determining Available Bandwidth for Direct ASI Systems
This section provides procedures for operators with direct ASI to use in determining
This section provides procedures for operators with direct ASI to use in determining
how much bandwidth is available for inband sources. To determine the amount of
bandwidth available for additional bootloader carousels, perform the following
calculation:
Total Available Bandwidth - Bandwidth in Use = Available Bandwidth
Notes:
The inband data rate for a 64-QAM is 26 Mbps.
The inband data rate for a 256-QAM is 37 Mbps.
These rates are due to modulation coding and error corrections (real rates are
higher).
1 Open an xterm window on the DNCS.
2 Type one of the following, based on the system release you have installed:
2 Type one of the following, based on the system release you have installed:
For SR 4.2.1 and earlier, type cd /export/home/dncs/doctor and press Enter.
For SR 4.3 and later, type cd /dvs/dncs/Utilities/doctor and press Enter.
Note: Be sure to type a space between cd and /.
Result: The current directory is now the doctor directory.
Result: The current directory is now the doctor directory.
3 Type doctor -bv and press Enter. A table appears that lists the inband and out-
of-band data rates on the BFS carousel. The total inband carousel bandwidth in
use is displayed in the Aggregate IB Carousel Datarate field.
4 Subtract the total inband carousel bandwidth in use from the total available
bandwidth to determine the unused inband bandwidth on the BFS.
Examples:
Examples:
64-QAM: If your total inband carousel bandwidth in use is 14 Mbps, the
available bandwidth is 12 Mbps.
26 - 14 = 12 Mbps
256-QAM: If your total inband carousel bandwidth in use is 14 Mbps, the
available bandwidth is 23 Mbps.
37 - 14 = 23 Mbps
5 Compare the amount of unused bandwidth to the amount of bandwidth
required for the additional bootloader carousels.
6 Is there enough bandwidth to add the new bootloader carousels? (Bootloader
carousels require data rates between 1.00 and 3.00 Mbps.)
If yes, go to Add a Bootloader Source to the DNCS (on page 59).
If no, refer to Recommendations for Data Carousel Rate Management Technical
Bulletin (part number 716377) for details on how to increase the bandwidth of
your system.