user manual

Configuring Headend Broadband Access Router Features
Configuring the Upstream Cable Interface
MC-548
Cisco IOS Multiservice Applications Configuration Guide
Verifying the Upstream Input Power Level
To verify the current value of the upstream input power level, enter the show controllers cable command
for the upstream port you have just configured:
CMTS01# show controllers cable 6/0 u0
Cable6/0 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
Troubleshooting Tips
To troubleshoot the configuration, perform the following tasks:
• Verify that the upstream amplitude of an optimal RF carrier injected at the fiber node reference input
point reaches the MC16C input point at a consistent level (node-to-node and port-to-port), and that
this absolute level as installed matches both the design and software settings on the Cisco uBR7200
series.
• Software adjustments of 1 to 3 dB can be used to adjust for minor variations in measurement or setup
and port-to-port calibration differences. These adjustments can significantly improve cable modem
performance, especially in marginal situations. Larger adjustments should be made in conjunction
with spectrum analyzer-support in the headend.
Activating Upstream Admission Control
The admission control is set as a percentage of the specified upstream channel capacity. The acceptable
range is from 10 to 1000 percent. Admission control is disabled by default.
To set the upstream admission control, use the following command in cable interface configuration
mode:
Verifying Upstream Admission Control
To verify whether or not upstream admission control has been configured and activated, enter the show
running-config command in privileged EXEC mode and look for the cable interface configuration
information. If upstream admission control has been configured and enabled, an admission control entry
will be displayed in the show running-config output, indicating the user-defined percentage of upstream
channel capacity allowable. If upstream admission control is disabled, no admission control entry will
be displayed in the output.
CMTS01# show running-config
Command Purpose
CMTS01(config-if)# cable upstream usport admission-control
percentage
Sets the admission control as a percentage of the
upstream channel capacity. Valid range is from 10 to
1000 percent.