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Cisco uBR7200 Series Universal Broadband Router Software Configuration Guide
OL-2239-05
Chapter 1 Overview of Cisco uBR7200 Series Software
Supported Software Features for the Cisco uBR7200 Series
The following example of the show cable qos profile command illustrates that the maximum
downstream burst has been defined, and is a management-created QoS profile:
Router# show cable qos pro
ID Prio Max Guarantee Max Max TOS TOS Create B IP prec.
upstream upstream downstream tx mask value by priv rate
bandwidth bandwidth bandwidth burst enab enab
1 0 0 0 0 0 0xFF 0x0 cmts(r) no no
2 0 64000 0 1000000 0 0xFF 0x0 cmts(r) no no
3 7 31200 31200 0 0 0xFF 0x0 cmts yes no
4 7 87200 87200 0 0 0xFF 0x0 cmts yes no
6 1 90000 0 90000 1522 0xFF 0x0 mgmt yes no
10 1 90000 0 90000 1522 0x1 0xA0 mgmt no no
50 0 0 0 96000 0 0xFF 0x0 mgmt no no
51 0 0 0 97000 0 0xFF 0x0 mgmt no no
The following example illustrates the maximum downstream burst size in sample QoS profile 10 with
the show
cable qos prof verbose command in privileged EXEC mode:
Router# show cable qos pro 10 ver
Profile Index 10
Name
Upstream Traffic Priority 1
Upstream Maximum Rate (bps) 90000
Upstream Guaranteed Rate (bps) 0
Unsolicited Grant Size (bytes) 0
Unsolicited Grant Interval (usecs) 0
Upstream Maximum Transmit Burst (bytes) 1522
Downstreamam Maximum Transmit Burst (bytes) 100000
IP Type of Service Overwrite Mask 0x1
IP Type of Service Overwrite Value 0xA0
Downstream Maximum Rate (bps) 90000
Created By mgmt
Baseline Privacy Enabled no
Usage Guidelines If a cable modem registers with a QoS profile that matches one of the existing QoS profiles on the Cisco
CMTS, then the maximum downstream burst size, as defined for that profile, is used instead of the
default DOCSIS QoS profile of 1522.
For example, a DOCSIS 1.0 configuration that matches QoS profile 10 in the previous examples would
be as follows:
03 (Net Access Control) = 1
04 (Class of Service Encodings Block)
S01 (Class ID) = 1
S02 (Maximum DS rate) = 90000
S03 (Maximum US rate) = 90000
S06 (US burst) = 1522
S04 (US Channel Priority) = 1
S07 (Privacy Enable) = 0
The maximum downstream burst size (as well as the ToS overwrite values) are not explicitly defined in
the QoS configuration file because they are not defined in DOCSIS. However, because all other
parameters are a perfect match to profile 10 in this example, then any cable modem that registers with
these QoS parameters has a maximum downstream burst of 100000 bytes applied to it.
For further illustration, consider a scenario in which packets are set in lengths of 1000 bytes at 100
packets per second (pps). Therefore, the total rate is a multiplied total of 1000, 100, and 8, or 800kbps.
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