The cable interface in the Cisco cBR router supports upstream signals and serves as the radio frequency (RF) interface. This
chapter provides an overview of the upstream interfaces on the Cisco cBR Series Converged Broadband Router.
Cisco IOS XE Fuji 16.9.1 and later releases support 10 Gbps of upstream throughput on the following line cards on the Cisco cBR Series Converged Broadband Router:
Upstream Channel Management
Upstream Channel Management (UCM) is responsible for the physical
(PHY) layer configuration and resource management of upstream channels in the
Cisco cBR Series Converged Broadband Router.
An upstream port represents a physical upstream RF connector on a
cable line card, connected to one or more fiber nodes. An upstream RF port is a
container of upstream RF channels, which imposes constraints on both topology
and spectrum for the group of RF channels contained in the physical port. An
upstream RF port also represents the RF front-end hardware component on a cable
line card including the connector, variable gain adjustment (VGA), and A/D
converter. This is directly connected to a set of upstream physical channel
receivers. The number of upstream physical channels per port is thus
constrained by the number of receivers accessible to the port.
An upstream RF channel represents DOCSIS physical layer operation on
a single upstream center frequency with a particular channel width. It is
contained by a single physical port on the CMTS line card hardware.
Upstream Resource Management
The upstream resource management (URM) feature is primarily
responsible for the maintenance of the relationship between a physical upstream
connector on the line card and the upstream RF channels received on that