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Cisco uBR10012 Universal Broadband Router Software Configuration Guide
OL-1520-08
Chapter1 Overview of CiscouBR10012 Universal Broadband Router Software
Supported Software Features for the CiscouBR10012 Router
Commands
Router# show interface cable x/0 service-flow [sfid] phs
Router# debug cable error
Router# debug cable phs
For additional command information, refer to the CiscoBroadband Cable Command Reference Guide
on Cisco.com.
DOCSIS 1.1 Quality of Service Support
Enhanced quality of service (QoS) gives priority for real-time traffic such as voice and video.
•The DOCSIS 1.0 QoS model (a service ID (SID) associated with a QoS profile) has been replaced
with a service flow model that allows greater flexibility in assigning QoS parameters to different
types of traffic and in responding to changing bandwidth conditions.
•DOCSIS 1.1 offers support for multiple service flows per CM, which allows a single CM to support
a combination of data, voice, and video traffic.
•DOCSIS 1.1 offers greater granularity in QoS per CM in either direction, using unidirectional
service flows.
•Dynamic MAC messages create, modify, and delete traffic service flows to support on-demand
traffic requests
•Supported QoS models for the upstream are:
–
Best-effort—Data traffic sent on a non-guaranteed best-effort basis
–
Committed Information Rate (CIR)—Guaranteed minimum bandwidth for data traffic
–
Unsolicited Grants (UGS)—Constant bit rate (CBR) traffic, such as voice, that is characterized
by fixed size packets at fixed intervals
–
Real-Time Polling (RTPS)—Real-time service flows, such as video, that produce unicast,
variable-size packets at fixed intervals
–
Unsolicited Grants with Activity Detection (USG-AD)—Combination of UGS and RTPS, to
accommodate real-time traffic that might have periods of inactivity (such as voice using silence
suppression). The service flow uses UGS fixed grants while active, but switches to RTPS
polling during periods of inactivity, to avoid wasting unused bandwidth.
The DOCSIS 1.1 QoS framework is based on the following objects:
•Service class—A collection of settings maintained by the CMTS that provide a specific QoS service
tier to a CM that has been assigned a service flow within a particular service class.
•Service flow—A unidirectional sequence of packets receiving a service class on the DOCSIS link.
•Packet classifier—A set of packet header fields used to classify packets onto a service flow to
which the classifier belongs.
•PHS rule—A set of packet header fields that are suppressed by the sending entity before
transmitting on the link and that are restored by receiving entity after receiving a header-suppressed
frame transmission. Payload Header Suppression increases the bandwidth efficiency by removing
repeated packet headers before transmission.
In DOCSIS 1.1, the basic unit of QoS is the service flow, which is a unidirectional sequence of packets
transported across the RF interface between the CM and CMTS. A service flow is characterized by a set
of QoS parameters such as latency, jitter, and throughput assurances.
Every CM establishes a primary service flow in both the upstream and downstream directions. The
primary flows maintain connectivity between the CM and CMTS at all times.
In addition, a DOCSIS 1.1 CM can establish multiple secondary service flows. The secondary service
flows either can be created permanently (they persist until the CM is reset or powered off) or can be
created dynamically to meet the needs of the on-demand traffic being transmitted.