Cisco Systems uBR7200 manual Verifying the Upstream Frequency, MC-545

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
	CMTS01(config-if)#cable upstream usport frequency	Sets a fixed upstream frequency when you enter the
	up-freq-hz	fixed center frequency for your upstream RF carrier
		in Hz. Valid range for usport is from 0 to 5 if you are
		using the MC16 cable modem card.
Step 2
	CMTS01(config-if)# no cable upstream usport +	Places the upstream port in the “admin up” state.

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

MC-545