Chapter 9: Upstream Cable Access Modules (UCAMs)
STANDARD Revision 1.0
C4® CMTS Release 8.3 User Guide
© 2016 ARRIS Enterprises LLC. All Rights Reserved.
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• Map size (in 800 microsecond ticks)
• SCDMA codes per slot
• Slot size (in 6.25 microsecond ticks)
For all other upstream parameters, if you do not specify a logical channel, then the CLI code will apply the change to the
physical interface. In other words, both logical channels of the upstream will be affected.
For example, the following command does not specify a logical channel, and it affects the entire upstream:
configure interface cable-upstream 5/0 no shutdown
The following command brings up only logical channel 0:
configure interface cable-upstream 5/0.0 no shutdown
The following command assigns modulation profile 3 to upstream channel 5/0:
configure interface cable-upstream 5/0 cable modulation-profile 3
4 Periodic Ranging (Also called Station Maintenance). Cable modems use this IE to perform station maintenance. This IE is
unicast. Only the range request message — no other data — can be sent using this IE.
5 Short Data Grants This unicast IE gives permission to a specific cable modem to transmit one or more Protocol Data
Units (PDUs). The cable modem uses this region in the upstream map interval if the number of minislots required to send
the message is less than or equal to the maximum burst interval specified for a short data grant in the Upstream Channel
Descriptor (UCD) message. The reason that grants can be split into short and long data grants is for the sake of FEC
encoding. Short data grants are used only when a cable modem is transmitting via an upstream channel that is compatible
with DOCSIS 1.X.
6 Long Data Grants This unicast IE gives permission to a specific cable modem to transmit one or more PDUs. The cable
modem uses this region in the upstream map interval if the number of minislots required to send the message is greater
than the maximum burst interval for a short data grant in the Upstream Channel Descriptor (UCD) message. The reason
that grants can be split into short and long data grants is for the sake of FEC encoding. Long data grants are used only when
a cable modem is transmitting via an upstream channel that is compatible with DOCSIS 1.X.
Note: The following Advanced PHY types are provided for channels carrying combined DOCSIS 1.x and DOCSIS 2.0 bursts
and also for channels carrying DOCSIS 2.0 bursts.
9 Advanced PHY Short This IE is the same as a short data grant except that it is used when the cable modem is
communicating via an upstream channel that is DOCSIS 2.0 compatible.
10 Advanced PHY Long This IE is the same as a long data grant except that it is used when the cable modem is
communicating via an upstream channel that is DOCSIS 2.0 compatible.