user manual

Configuring Headend Broadband Access Router Features
Configuring and Activating Frequency Agility
MC-566
Cisco IOS Multiservice Applications Configuration Guide
Frequency Management Policy
Upstream port frequency should be set to a fixed value during system installation and testing. This value
is chosen from the allocation plan for the RF domain for the RF plant segment connected to the upstream.
Note Having fixed frequency settings is recommended during early deployment at least until
amplifier cascade adjustments or plant repair becomes infrequent for the nodes connected
to the upstream port. When multiple upstream ports are combined to provide increased
bandwidth, care should be taken to prevent overlapping frequency bands.
When the system has reached sufficient stability, the RF domain topology can be entered into the
Cisco IOS configuration file to enable RF spectrum management. This management feature—also called
frequency agility—applies a common frequency management policy to a set of upstream ports.
Spectrum management or frequency agility is configured and activated using spectrum groups. A
spectrum group is a frequency hop table that can be used by upstream ports to implement a
frequency-hopping policy. There are four types of frequency-hopping policies: blind, scheduled,
combined blind and scheduled, and guided.
Note When each upstream port has its own RF domain, the group is called a nonshared spectrum
group. When multiple upstream ports share the same RF domain, the group is called a
shared spectrum group.
Note The cable interface will not operate until you either create and configure a spectrum group
or set a fixed upstream frequency. From the interface configuration prompt, an interface is
assigned membership in a spectrum group. From the interface point of view, the spectrum
group also represents the set of upstreams connected to the same group of fiber nodes. The
spectrum manager is able to determine if upstream frequencies need to be managed
together.
In general, when defining your spectrum use the following guidelines:
• Avoid frequencies with known ingress problems such as amateur radio bands or short-wave bands.
• Avoid hostile spectrum below 20 MHz.
• Allow extra bands for frequency hopping.
• Place upstream ports in the same combiner group in a shared spectrum group.
• Use the receive power level setting to perform slight equalization adjustments.
Frequency agility is configured and activated using spectrum groups that are controlled by the spectrum
manager. You can create from 1 to 32 spectrum groups for each Cisco uBR7200 series cable modem card
upstream port.
To configure and activate frequency agility, perform the tasks in the following sections:
• Determining the Upstream Ports Assigned to a Combiner Group
• Creating Spectrum Groups
• Configuring and Activating Spectrum Groups