Payload Header Suppression; Downstream Tos Overwrite; Docsis 1.1 Quality Of Service; Service Flow - Cisco cBR 8 Configuration Manual
Cbr series converged broadband routers
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Also See for cBR 8:
- Installation instructions manual (27 pages) ,
- Configuration and troubleshooting manual (254 pages) ,
- Hardware installation manual (270 pages)
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Payload Header Suppression
Payload Header Suppression
Payload header suppression (PHS) conserves link-layer bandwidth by suppressing repetitive or redundant
packet headers on both upstream and downstream service flows. PHS is enabled or disabled per service flow,
and each service flow can support a separate set of PHS rules that determine which parts of the header are
suppressed. This ensures that PHS is done in the most efficient manner for each service flow and its particular
type of application.
Downstream ToS Overwrite
Downstream ToS Overwrite is supported in DOCSIS 1.1. It can be used in IPv4 and IPv6 environment. You
can use CLI command cable service class class-index tos-overwrite and-mask or-mask or the cable modem
configuration file to configure downstream ToS overwrite.
DOCSIS 1.1 Quality of Service
The DOCSIS 1.1 QoS framework is based on the following objects:
• Service flow—A unidirectional sequence of packets on the DOCSIS link. Separate service flows are
• Service class—A collection of settings maintained by the CMTS that provide a specific QoS service tier
• Packet classifier—A set of packet header fields used to classify packets onto a service flow to which
• Payload header suppression (PHS) rule—A set of packet header fields that are suppressed by the sending
See the following sections for more information on these components.
Service Flow
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 cable modem and CMTS. A service flow defines a set of QoS
parameters such as latency, jitter, and throughput assurances, and these parameters can be applied independently
to the upstream and downstream traffic flows. This is a major difference from DOCSIS 1.0 networks, where
the same QoS parameters were applied to both the downstream and upstream flows.
Note
DOCSIS 1.0 networks used service IDs (SIDs) to identify the QoS parameter set for a particular flow.
DOCSIS 1.1 networks use the service flow ID (SFID) to identify the service flows that have been assigned
to a particular upstream or downstream. DOCSIS 1.1 networks still use the term SID, but it applies
exclusively to upstream service flows.
Cisco cBR Series Converged Broadband Routers Quality of Services Configuration Guide for Cisco IOS XE
Fuji 16.7.x
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used for upstream and downstream traffic, and define the QoS parameters for that traffic.
to a cable modem that has been assigned a service flow associated with that service class.
the classifier belongs. The CMTS uses the packet classifiers to match the packet to the appropriate
service flow.
entity before transmitting on the link, and are restored by the receiving entity after receiving a
header-suppressed frame transmission. PHS increases the bandwidth efficiency by removing repeated
packet headers before transmission.
DOCSIS 1.1 for the Cisco CMTS Routers
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