Chapter 8: Downstream Cable Access Modules (DCAMs)
STANDARD Revision 1.0
C4® CMTS Release 8.3 User Guide
© 2016 ARRIS Enterprises LLC. All Rights Reserved.
231
Beginning with Release 8.1.5 the XD CAM supports 32 channels in both Annex A and Annex B.
The XD CAM is supported by both the C4 and C4c CMTS chassis.
Although the C4/C4c CMTS chassis can support both Annex A and Annex B simultaneously, an individual XD CAM must
be configured for either Annex A or B. It cannot support both annexes at the same time.
Hitless sparing is supported by spare groups up to 8 + 1 in size (eight active XD CAMs plus one spare).
Non-hitless sparing is supported up to 9 + 1, (nine active XD CAMs plus one spare).
Note: For optimal per-CAM throughput, no more than eight (8) active XD CAMs should be provisioned in a C4 CMTS
chassis.
Sparing groups must be homogeneous: they must not mix Annex A and Annex B CAMs or 16D CAMs with XD CAMs.
Only slots 0-15 can be provisioned for the XD CAM; slot 16 is not used.
The XD CAM uses the 16D PIC.
32 channel operation at full line rate is only possible for Annex B due to bandwidth limitations in the system.
Annex A XD CAMs support only one interleaver depth setting, 12. This is in keeping with the EuroDOCSIS specifications.
As stated on see "
Downstream Interleaver Settings
(page 224), Annex B XD CAMs can support two different interleaver
depth settings, but all the channels on a given RF connector must have the same setting. Changing the setting for one
channel changes it for all of the channels of that RF connector. See also
The Enhanced Power Mode feature is available only to Annex A XD CAMs. The command to enable [disable] Enhanced
Power is
configure cable downstream-enhanced-power [no]
.
The C4/C4c CMTS permits Annex A channels to be configured with center frequencies from 85-999 MHz.
When operating in Annex A, all of the 1-8 XD CAM channels assigned to a given RF connector must be grouped in a
spectrum window of 80 MHz. The center frequencies of Annex A channels must be separated by 8 MHz or an integral
multiple of 8 MHz.
The step size of the spectrum window is 125 kHz for both Annex A and Annex B.
The channels in the spectrum window must be arranged on an evenly spaced grid. This means that once you pick the
first channel frequency on a multiple of 125 kHz, then all other channels on the same RF connector must have
frequencies separated by exact multiples 8 or 6 MHz, depending on whether Annex A or B is used. Once the first
channel is selected, the remaining channels in the spectrum window can be added using higher or lower frequencies.
See see "
Spectrum Window and Frequency Grid for Channels on the Same F-connector
The XD CAM supports the 56-bit DES encryption algorithm.
The CLI command
configure slot <> type 24DCAM-A
results in a slot provisioned for a 32DCAM-A. The CLI
keyword
24DCAM-A
is deprecated: it will be accepted but will not appear in the output of this command or in those of
the show commands. It is translated to
32DCAM-A
by the CLI.