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Cisco uBR10012 Universal Broadband Router Software Configuration Guide
OL-1520-05
Chapter 3 Configuring Cable Interface Features for the Cisco uBR10012 Router
Configuring the Upstream Cable Interface
For additional information about channel width and minislot size, refer to the
Cable Radio Frequency
(RF) FAQs
at
http://www.cisco.com/en/US/customer/tech/tk86/tk319/technologies_q_and_a_item09186a0080134faa
.shtml
.
Verifying Upstream Channel Width
To verify the current value of the upstream channel width, enter the
show controllers cable
command
for the upstream port you just configured. A sample follows below:
Router#
show controllers cable5/0/0 u0
Cable5/0/0 Upstream 0 is up
Frequency 24.016 MHz, Channel Width 0.800 MHz, QPSK Symbol Rate 0.640 Msps
Spectrum Group is overridden
SNR 33.2560 dB
Nominal Input Power Level 0 dBmV, Tx Timing Offset 2288
Ranging Backoff automatic (Start 0, End 3)
Ranging Insertion Interval automatic (60 ms)
Tx Backoff Start 0, Tx Backoff End 4
Modulation Profile Group 1
Perform these steps if you are having difficulty with verification:
Step 1
Use a valid combination of modulation format (QPSK and QAM-16), minislot size, frequency, and the
no shutdown
command.
Step 2
Use a recommended or previously tested modulation profile. It is not uncommon to create a modulation
profile that does not allow cable interface-to-headend communication. Because each message type is
individually specified, some messages might not work.
Step 3
Verify using IP ping packets of varying lengths (64 to 1500 bytes). Ping from the headend to the
cable interface.
Step 4
Verify with your cable interface vendor that your CM software is fully certified or compatible with
DOCSIS 1.0 and extensions, as appropriate.
Setting the Upstream Frequency
The upstream channel frequency of your RF output must be set to comply with the expected input
frequency of your Cisco cable interface line card. To configure upstream channel frequencies, perform
one of the following tasks:
•
Configure a fixed frequency from 5 to 42 MHz for NTSC operations, then enable the upstream port.
•
Create a global spectrum group, assign the interface to it, and enable the upstream port.
Note
You can also select a default that does not set a specific fixed value.
Note
The upstream port is frequency agile. If you define spectrum groups, the frequency can change while the
interface is up and carrying traffic.
A modulation profile consists of a table of physical layer characteristics for the different types of
upstream bursts; for example, initial maintenance, long grant, request/data, request, short grant, and
station maintenance.
