Installation guide

3-10
Cisco uBR7100 Series Universal Broadband Router Software Configuration Guide
OL-2238-03
Chapter 3 Configuring the Cisco Cable Interface
Configuring the Upstream Cable Interface
• “Activating Upstream Frequency Adjustment” section on page 3-18
• “Activating Upstream Power Adjustment” section on page 3-19
• “Activating Upstream Timing Adjustment” section on page 3-20
• “Activating the Upstream Ports” section on page 3-20
• “Setting Upstream Backoff Values” section on page 3-21
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 modem card. To configure upstream channel frequencies, perform one of
the following tasks:
• Configure a fixed frequency between 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.
Note The upstream cable interface does not operate until you either set a fixed upstream frequency or create
and configure a spectrum group.
If you are setting a fixed upstream frequency, make sure that the frequency selected does not interfere
with the frequencies used for any other upstream applications running on the cable plant.
To set a fixed upstream frequency, use the following commands in cable interface configuration mode.
Tip For NTSC operations, valid ranges are 5000000 to 42000000 Hz.
Command Purpose
CMTS01(config-if)# cable upstream usport
frequency up-freq-hz
Enter the fixed center frequency for your upstream
RF carrier in Hz.
CMTS01(config-if)# no cable upstream
usport shutdown
Place the upstream port in the “admin up” state.