Quality of Service for Voice on the Cisco uBR7200 Series Cable Router

Feature Overview

This feature describes the software enhancements that support quality of service (QoS) features for voice transmission over a DOCSIS cable network. These enhancements include improving support for

Delay/jitter requirements of real-time traffic typical of voice, video, and Fax traffic
Increase in per-modem data throughput,
New Media Access Control (MAC) scheduler
MAC messaging support to help support real-time response to your service requests

Benefits

This feature improves voice transmission over a DOCSIS cable network.

Restrictions

Baseline Privacy Interface (BPI) encryption is not supported when using dynamic Service IDs (SIDs).

Related Features and Technologies

Table 1 lists the IOS cable router features released in the IOS 12.0 timeframe.

Table 1 uBR7200 Series Cable Router Features Available Since 12.0 T

Available With: Category Feature

11.3(5)NA & 12.0(3)T

Cable Features

Feature Enhancements

11.3(6)NA

MC16 Modem Card

11.3(8)NA

Access List Support Enhancements

12.0(4)T

Downstream Channel ID Configuration

12.0(4)T

Multiple Service ID Support

12.0(4)T

Cable Modem and Host Subnet Addressing

12.0(5)T

Telephone Return

12.0(5)T

Time Server Functionality

12.0(7)T

Amplitude Averaging Compensation

12.0(7)XR

Cable Interface Bundling

12.0(7)XR

Enhanced Modem Status Display

12.0(7)XR

Show Interface Cable Command Verbose Enhancements

12.0(7)XR

IP Address Verification

12.0(7)XR

Registration Timeout Configuration

12.0(7)XR

Show Cable Modem Command Enhancements

12.0(7)XR

Modem Status Summary Enhancements

12.0(7)XR

Show Controller Command Enhancements

12.0(7)XR

Configuring Concatenation

12.0(7)XR

Virtual Private Network Support

12.0(7)XR

Blind Hopping Support on the MC16S Modem Card

12.0(7)XR

Signal-to-Noise Ratio Data Support

11.3(9)NA and 12.0(4)T

Cable QoS

QoS Profile Enforcement

12.0(4)T

Quality of Service for Voice

11.3(9)NA

Network Management

Upstream Traffic Shaping Feature

12.0(5)T

Enhanced-Spectrum Management

12.0(5)T

Downstream Rate Shaping with TOS bits

12.0(7)XR

Spectrum Management Using the MC16S Modem Card

12.0(7)XR

Downstream Test Signals Configuration

12.0(7)XR

Wireless Features

Point-to-Point Wireless Support

Supported Platforms

uBR7200 series cable router

Supported Standards, MIBs, and RFCs

Standards

DOCSIS 1.0+

MIBs

No new or modified MIBs are supported by this feature.

RFCs

No new or modified RFCs are supported by this feature.

Configuration Tasks

See the following to configure this quality of service feature.

Configuring a Modulation Profile (Required)

Configuring a Modulation Profile

Step	Command	Purpose
1.	Router(config)# cable qos-profile n name	Assigns a name to the QoS profile.
2.	Router(config)# cable qos-profile n priority	Sets the upstream traffic priority.
3.	Router(config)# qos-profile n max-upstream	Sets the maximum upstream traffic rate.
4.	Router(config)# qos-profile n guaranteed-upstream	Sets the guaranteed upstream traffic rate.
5.	Router(config)# qos-profile n grant-size	Sets the size for unsolicited grants.
6.	Router(config)# qos-profile n grant-interval	Sets the interval for unsolicited grants.
7.	Router(config)# qos-profile n max-burst	Sets the maximum rate for upstream transmission bursts.
8.	Router(config)# qos-profile n tos-overwrite	Sets the mask bits to overwrite the Type of Service byte.
9.	Router(config)# qos-profile n max-downstream	Sets the maximum downstream traffic rate.
10.	Router(config)# qos-profile n privacy	Enables baseline privacy.
11.	Router(config)# qos-profile n ip-precedence	Downstream settings are based on IP precedence.

Monitoring and Maintaining QoS for Voice

Command	Purpose
Router# show cable qos profile n	Displays the configuration for the specified profile.
Router# show interface cable x/y sid	Displays each Qos profile configured for the specified cable interface.
Router# show interface cable x/y upstream	Displays quality of service statistics for the upstream channel.

Configuration Examples

The following example shows how a cable modem with a QoS profile 30 created by the cable router (mgmt):

router(config)# cable qos profile 30 name qostest

router(config)# cable qos profile 30 grant-int 55

router(config)# cable qos profile 30 grant-size 100

router(config)# cable qos profile 30 guaranteed 60000

router(config)# cable qos profile 30 ip-prec 7

router(config)# cable qos profile 30 max-bur 256

router(config)# cable qos profile 30 max-down 3000

router(config)# cable qos profile 30 max-up 6000

router(config)# cable qos profile 30 prior 7

router(config)# cable qos profile 30 privacy

router# show cable qos profile 30

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

30 7    6000000   60000000  100000000   256   0x0  0x0    mgmt    yes   no

Command Reference

This section documents modified commands. All other commands used with this feature are documented in the Cisco IOS Release 12.0T command reference publications.

cable qos profile
show cable qos profile

Note For show and more commands: Required information. When show or more commands are documented for a feature, you must include the following standard text about the search and filter functionality (introduced in Release 12.0(1)T) immediately after the bulleted list of commands.

In Cisco IOS Release 12.0(1)T or later releases, you can search and filter the output for show and more commands. This functionality is useful when you need to sort through large amounts of output, or if you want to exclude output that you do not need to see.

To use this functionality, enter a show or more command followed by the "pipe" character (|), one of the keywords begin, include, or exclude, and an expression that you want to search or filter on:

: command | {begin | include | exclude} regular-expression

See the following example of the show atm vc command in which you want the command output to begin with the first line where the expression "PeakRate" appears:

: show atm vc | begin PeakRate

For more information on the search and filter functionality, refer to the Cisco IOS Release 12.0(1)T feature module CLI String Search.

cable qos profile

To configure a QoS profile, enter the cable qos profile global configuration command. To either set default values for profile group numbers 1 or 2 or remove the QoS profile if no specific parameters remain, enter the no form of this command.

: cable qos profile {groupnum | grant-interval {interval} | grant-size {size} | guaranteed-upstream {rate} | ip-precedence {value} | max-burst {rate} | max-downstream {rate} | max-upstream {rate} | name {string} | priority {value} | privacy | tos-overwrite {value}}
: no cable qos profile {groupnum | grant-interval {interval} | grant-size {size} | guaranteed-upstream {rate} | ip-precedence {value} | max-burst {rate} | max-downstream {rate} | max-upstream {rate} | name {string} | priority {value} | privacy | tos-overwrite {value}}

Syntax Description

groupnum	QoS profile group number. Qos profiles 1 and 2 are required by the system. QoS profile 1 is used during registration, and QoS profile 2 is the default QoS profile. Both profiles are preconfigured and cannot be removed. However, you can modify these profiles.
grant-interval	The periodic interval in microseconds at which the cable modem (CM) wants to send the fixed-sized upstream MAC frames. It is used to compute the period in between constant bit rate (CBR) slots for the CM. Valid range is from 0 to 65535.
grant-size	The size of the DOCSIS MAC frame the CM wants periodically to send on the upstream transmission. This value in bytes does not include any PHY layer overhead. It includes the complete fixed MAC frame size starting from the frame control byte to the CRC of the protocol data unit (PDU). This parameter is used by the CMTS to set the size of the periodic CBR slot for the CM after adding the PHY overhead.
guaranteed-upstream	Guaranteed minimum upstream rate in kilobytes per second. Valid values are from 0 to 100000. Default value is 0 (no reserved rate).
ip-precedence	Bits in the TOS byte that enable you to configure individual data rate limits on a per modem basis. Valid values are from 0 to 7.
max-burst	Maximum upstream transmit burst size in bytes that the modem can send for any single transmit burst. Valid values are from 0 to 65535 bytes. Default value is 0 (no limit).
max-downstream	Maximum downstream data rate in kilobytes per second that a modem using this QoS profile receives. Valid values are from 0 to 100000. Default value is 0 (no downstream rate limit).
max-upstream	Maximum upstream data rate in kilobytes per second that a modem using this QoS profile receives. Valid values are from 0 to 255. Default value is 0 (no upstream rate limit).
name	QoS name string.
priority	Relative priority number assigned to upstream traffic by this QoS profile. Valid values are from 0 to 7 with 7 being the highest priority. Default value is 0.
privacy	Enables cable baseline privacy.
tos-overwrite	Overwrite the Type of Service (TOS) field in the IP datagrams received on the upstream before forwarding them downstream (or IP backbone). This parameter sets the hexadecimal mask bits to a hexadecimal value, thereby helping the CMTS identify datagrams for QoS on the backbone. Valid range is from 0x0 to 0xFF.
value	The value substituted for the TOS value. See tos_overwrite.

Default

No default behavior or values.

Command Mode

Global configuration

Command History

Release	Modification
11.3 NA	This command was introduced.
12.0(3)T	Command was included in the mainline release.
12.0(5)T	The ip-precedence keyword was added and the max-downstream range was increased.
12.0(7)XR	Output was reorganized and name, grant-size, and grant-interval parameters were added.

Example

See the following example to configure QoS profile 4 with guaranteed upstream of 2 kbps, maximum transmission burst of 2, an IP precedence of 7, a maximum downstream rate of 300 kbps, with a priority of 4, cable baseline privacy set, and a tos-overwrite mask and value byte (in hex) of 0x7:

Router(config)# cable qos profile 4 name Mondayqos

Router(config)# cable qos profile 4 guaranteed-upstream 2

Router(config)# cable qos profile 4 max-burst 2

Router(config)# cable qos profile 4 ip-precedence 7 max-downstream 300

Router(config)# cable qos profile 4 priority 4

Router(config)# cable qos profile 4 tos-overwrite 0x7

Related Commands

Command	Description
cable qos permission	Configures permissions for updating the QoS table.
show cable qos profile	Displays QoS profiles.

show cable qos profile

To display QoS profiles, use the show cable qos profile privileged EXEC configuration command.

: show cable qos profile qos profile index [verbose]

Syntax Description

qos profile index	(Optional) Displays the index of the QoS profile specified.
verbose	(Optional) Displays all details for the specified QoS profile index.

Command Mode

Privileged EXEC

Command History

Release	Modification
11.3(5(NA)	This command was introduced.
12.0(3)T	The command was included in the mainline release.
12.0(5)T	tos-overwrite option was added.
12.0(7)XR	verbose option was added.

Examples

The following example shows the full QoS table for profile 30:

router# show cable qos profile 30 verbose

Profile Index                           30

Name                                    test

Upstream Traffic Priority               7

Upstream Maximum Rate (bps)             6000000

Upstream Guaranteed Rate (bps)          60000000

Unsolicited Grant Size (bytes)          100

Unsolicited Grant Interval (usecs)      55000

Upstream Maximum Transmit Burst (bytes) 256

IP Type of Service Overwrite Mask       0x0

IP Type of Service Overwrite Value      0x0

Downstream Maximum Rate (bps)           100000000

Created By                              mgmt

Baseline Privacy Enabled                yes

IP precedence rate limits

 IP precedence						                            2

 Rate Limit                             100000

Table 2 describes the fields shown in the show cable qos profile displays.

Table 2 Show cable qos profile Command Field Descriptions

Field	Description
Profile Index	Profile number.
Name	The name string for this profile.
Upstream Traffic Priority	Priority level for upstream traffic.
Upstream Maximum Rate (bps)	Maximum upstream transmission rate in bits per second.
Upstream Guarantee Rate (bps)	Guaranteed minimum upstream rate in bits per second.
Unsolicited Grant Size (bytes)	Number of grant-size parameters in bytes. Grant Size is used by the CMTS to set the size of the periodic CBR slot for the CM after adding the PHY overhead.
Unsolicited Grant Interval (usecs)	Number of unsolicited grant intervals in microseconds. The grant-interval parameter is used to compute the period in between CBR slots for the CM.
Upstream Maximum Transmit Burst (bytes)	Maximum transmit burst size in bytes.
IP Type of Service Overwrite Mask	Hex value of the mask bits.
IP Type of Service Overwrite Value	Value of the mask byte. This is the value the CMTS will overwrite into the ToS field (after masking bits specified in the ToS-mask parameter) of the IP datagram before forwarding the datagram into IP backbone/downstream. The IP ToS overwrite feature helps to propagate cable access QoS onto the IP backbone.
Downstream Maximum Rate (bps)	Minimum upstream transmission rate in bits per second.
Created by	Identity of the profile creator.
Baseline Privacy Enabled	Reports yes if Baseline Privacy is enabled for this QoS profile. Reports no if Baseline Privacy is not enabled for this Qos profile.
IP Precedence rate limits	Value of the IP precedence and the transmission rate limit in bits per second.

Related Commands

Command	Description
cable qos permission	Sets permissions for updating QoS tables.
cable qos profile	Configures QoS profiles.
show cable qos permission	Displays the status of permissions for updating QoS tables.

Debug Commands

This section documents new debug commands. All other commands used with this feature are documented in the Cisco IOS Release 12.0T command reference publications.

debug cable dynsrv
debug cable scheduler

debug cable dynsrv

To display debug messages for all dynamic MAC messages at the router, use the debug cable dynsrv privileged EXEC mode command. To stop debugging dynamic MAC messages, use the no form of this command.

: [no] debug cable dynsrv

Syntax Description

: This command has no arguments or keywords.

Defaults

No default behavior or values.

Command History

Release	Modification
12.0(7)XR	This command was introduced.

Examples

The following example shows the message you receive when you turn debugging on and off:

router# debug cable dynsrv

CMTS dynsrv debugging is on

router# no debug cable dynsrv

CMTS dynsrv debugging is off

Related Commands

Command	Description
debug cable scheduler	Displays debug messages for admission control activity and reception of unsolicited grants.

debug cable scheduler

To display debug messages for admission control activity and reception of unsolicited grants, use the debug cable scheduler privileged EXEC command. To stop debugging, use the no form of this command.

: [no] debug cable scheduler [admission-control | unsolicited-grants]

Syntax Description

admission-control

Debugs admission control activity.

unsolicited-grants

Debugs the average delay and maximum delay jitter of unsolicited grants received by a specified SID for a specified cable interface.

Note: Make sure only one debugging SID is active per cable interface at a time.

Defaults

No default behavior or values.

Command History

Release	Modification
12.0(7)XR	This command was introduced.

Examples

The following example shows the message you receive when you turn debugging on and off:

router# debug cable sched

CMTS scheduler debugging is on

router# no debug cable sched

CMTS scheduler debugging is off

To debug admission control activity of the new MAC scheduler on a cable interface c3/0, see the following command:

router# debug cable scheduler admission-control

router# debug cable interface cable 3/0

To debug the average delay, maximum delay jitter on the unsolicited grants received by SID 9 on cable interface cable 3/0, see the following command:

router# debug cable scheduler unsolicited-grants

router# debug cable interface cable 3/0 sid 9

Related Commands

Command	Description
debug cable dynsrv	Debugs dynamic MAC messages.

Table of Contents

Debug Commands debug cable dynsrv Syntax Description Defaults Command History Examples Related Commands debug cable scheduler Syntax Description Defaults Command History Examples Related Commands