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. 234
15. If you have purchased a new XD CAM Module, it will show the new port designations: Mode 0, Mode 1, Mode 2, and
Mode 3.
Maximum Number of XD CAMs per C4 CMTS
With a single 10 gigabitEthernet interface on an RCM, the C4 CMTS is limited to a maximum of 10 Gbps of traffic upstream
and downstream. A maximum of eight XD CAMs running at full capacity can be supported. More than eight active XD CAMs
is permitted, but because of the 10 Gbps limit of a simplex RCM, they will not reach their maximum combined throughput.
On a duplex C4 CMTS there are two RCMs connected by a cross-over cable. In duplex mode the ports on both RCMs are
active, and it is possible to use both 10 gigE interfaces with the proper routing configuration.
Note: Each MAC domain must consist of channels from exactly one XD CAM or 16D CAM and exactly one 12U or 24U CAM.
In other words, the MAC domain cannot include ports from more than one downstream or from more than one upstream
CAM.
The XD CAM hardware supports:
Up to thirty-two channels numbered 0-31:
If configured for Annex B, the downstream channels use the frequency range of 57 to 999 MHz and carry 40 Mbps per
channel.
If configured for Annex A, the downstream channels use the frequency range of 85 to 999 MHz and carry 55 Mbps per
channel.
Four RF block upconverters (numbered 0-3). The process of combining multiple carriers digitally and then upconverting
with a single block upconverter is referred to as RF block upconversion, and the group of carriers that is block
upconverted is referred to as an RF block upconverter group. Each RF block upconverter can support up to eight
channels simultaneously.
Four downstream physical connectors (numbered 0-3) which are hard-wired to correspond to one RF block
upconverter each. These are located on the PIC.
Note: The XD hardware supports downstream center frequencies up to 999 MHz, but for the best performance it is
advisable to go no higher than 960 MHz. The downstream maximum center frequency must be set appropriately using the
following command:
configure cable freq-ds-max
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