Configuring Headend Broadband Access Router Features
Configuring the Upstream Cable Interface
To set a fixed upstream frequency, use the following commands in cable interface configuration mode:
| Command | Purpose |
Step 1 |
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Sets a fixed upstream frequency when you enter the | ||
| fixed center frequency for your upstream RF carrier | |
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| in Hz. Valid range for usport is from 0 to 5 if you are |
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| using the MC16 cable modem card. |
Step 2 |
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Places the upstream port in the “admin up” state. | ||
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To configure the default upstream frequency (which is no fixed frequency), enter the cable upstream usport frequency command without specifying a center frequency.
Verifying the Upstream Frequency
To verify the current value of the upstream frequency, 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 1.600 MHz, QPSK Symbol Rate 1.280 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
Note The upstream frequency displayed in the show controllers cable command output might not match the frequency that you entered when you set the upstream frequency. The Cisco uBR7200 series might select an upstream frequency close to the frequency you entered that offers better performance. The minimum upstream frequency step size on the MC16C is 32 kHz. The Cisco uBR7200 series selects the closest frequency available.
Troubleshooting Tips
To troubleshoot the configuration, perform the following tasks:
•Make sure the cable connections are not loose or disconnected.
•Make sure the Cisco cable modem card is firmly seated in its chassis slot and the captive installation screws are tight.
•Make sure you entered the correct slot and port numbers when you typed the command.
•Make sure you entered the correct upstream port number:
–On the MC16C cable modem card, this can be u0 to u5.
–On the MC14C cable modem cards, this can be u0 to u3.
–On the MC12C cable modem cards, this can be u0 or u1.
–On the MC11C cable modem cards, this can be u0 only.
•Make sure you selected a valid frequency for your headend.
Cisco IOS Multiservice Applications Configuration Guide
