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Service Flow Admission Control for the Cisco CMTS
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Table Of Contents

Service Flow Admission Control for the Cisco CMTS

Contents

Prerequisites for Service Flow Admission Control

Restrictions for Service Flow Admission Control

Information About Service Flow Admission Control

Overview of Service Flow Admission Control for the Cisco CMTS

Service Flow Admission Control and Cisco Universal Broadband Routers

Service Flow Admission Control on the Cisco uBR10012 Universal Broadband Router

Service Flow Admission Control on the Cisco uBR7246VXR Universal Broadband Router

Service Flow Admission Control and Memory Requirements for the Cisco CMTS

Service Flow Admission Control and Cisco CMTS Resources

Service Flow Admission Control and CPU Utilization

Service Flow Admission Control and Memory Utilization

Service Flow Admission Control and Upstream or Downstream Bandwidth Utilization

Categorization of Service Flows

Thresholds for Upstream or Downstream Bandwidth

Exclusive and Non-Exclusive Bandwidth Thresholds

Comparing Service Flow Admission Control with Prior Admission Control

How to Configure, Monitor and Troubleshoot Service Flow Admission Control

Enabling Service Flow Admission Control for Event Types

Prerequisites

Examples

What to Do Next

Configuring Service Flow Admission Control Based on CPU Utilization

Prerequisites

Configuring Service Flow Admission Control Based on Memory Resources

Prerequisites

Defining Rules for Service Flow Categorization

Examples

Troubleshooting Tips

What to Do Next

Naming Application Buckets for Service Flow Admission Control

Examples

Troubleshooting Tips

What to Do Next

Setting Downstream and Upstream Application Thresholds

Precedence of These Configuration Commands

Examples

Troubleshooting Tips

What to Do Next

Preempting High-Priority Emergency 911 Calls

Examples

Troubleshooting Tips

What to Do Next

Calculating Upstream and Downstream Bandwidth Utilization

Example

Bandwidth Validity Checks for Service Flow Admission Control

Implicit Bandwidth

Oversubscription

Displaying Application Buckets for Service Flow Admission Control

Prerequisites

Examples

Troubleshooting Tips

What to Do Next

Displaying Service Flow Reservation Levels

Prerequisites

Examples

Displaying SFAC Configuration and Status

Prerequisites

Examples

Troubleshooting Tips

What to Do Next

Debugging Service Flow Admission Control for Different Event Types

Prerequisites

Examples

What to Do Next

Debugging Service Flow Admission Control for CPU Resources

Prerequisites

Examples

What to Do Next

Debugging Service Flow Admission Control for Memory Resources

Prerequisites

Examples

What to Do Next

Debugging Service Flow Admission Control for Downstream Bandwidth

Prerequisites

Examples

What to Do Next

Debugging Service Flow Admission Control for Upstream Throughput

Prerequisites

Examples

What to Do Next

Debugging Flow Categorization for Service Flow Admission Control

Prerequisites

Examples

Troubleshooting Tips

What to Do Next

Configuration Examples for Service Flow Admission Control

Example of SFAC Configuration Commands

Example of Service Flow Admission Control for Downstream Traffic

Additional References

Related Documents

Standards

MIBs

Technical Assistance


Service Flow Admission Control for the Cisco CMTS

Revised: February 5, 2007, OL-1467-08

Cisco IOS Release 12.3(21)BC introduces Service Flow Admission Control (SFAC) on the Cisco Cable Modem Termination System. Service Flow Admission Control is supported on the Cisco uBR10012 router with Performance Routing Engines 1 and 2 (PRE1 and PRE2) modules, and the Cisco uBR7246VXR router. This document describes the concepts, advantages, configuration and monitoring capabilities of Service Flow Admission Control on the Cisco CMTS.

Note Admission Control is a widely-used term that applies to similarly named features for additional Cisco products and technologies.

One earlier version of Admission Control is introduced in Cisco IOS Release 12.3(13a)BC, and is described in the following document:

•Admission Control for the Cisco CMTS

http://www.cisco.com/en/US/products/hw/cable/ps2217/products_feature_guide_chapter09186a00804d2537.html

Another distinct version of Admission Control is supported for the Cisco uBR7114 universal broadband router in Cisco IOS 12.1 EC software. This earlier Admission Control feature sets the percentage of upstream channel capacity allowable for the given upstream. Refer to the following document:

•Cisco uBR7100 Series Software Configuration Guide

http://www.cisco.com/en/US/products/hw/cable/ps2211/products_configuration_guide_book09186a008007ca9a.html

Finding Feature Information in This Module

Your Cisco IOS software release may not support all of the features documented in this module. To reach links to specific feature documentation in this module and to see a list of the releases in which each feature is supported, use the "Additional References" section on page 16-43.

Finding Support Information for Platforms and Cisco IOS Software Images

Use Cisco Feature Navigator to find information about platform support and Cisco IOS software image support. Access Cisco Feature Navigator at http://www.cisco.com/go/fn. You must have an account on Cisco.com. If you do not have an account or have forgotten your username or password, click Cancel at the login dialog box and follow the instructions that appear.

Contents

•Prerequisites for Service Flow Admission Control

•Restrictions for Service Flow Admission Control

•Information About Service Flow Admission Control

•How to Configure, Monitor and Troubleshoot Service Flow Admission Control

•Configuration Examples for Service Flow Admission Control

•Additional References

Prerequisites for Service Flow Admission Control

Service Flow Admission Control requires the following:

•Cisco IOS Release 12.3(21)BC or later supporting release

•Cisco uBR10012 router with Performance Routing Engine Modules 1 or 2 (PRE1 or PRE2), or the Cisco uBR7246VXR router

Restrictions for Service Flow Admission Control

SFAC in Cisco IOS Release 12.3(21)BC follows these general factors when implementing on the Cisco CMTS:

•Configure SFAC before admitting any static or dynamic service flows. The best option is to have the configuration in place during startup time, or before the interface is up.h

•SFAC in Cisco IOS Release 12.3(21)BC supports the following resource monitoring on the Cisco CMTS:

–Upstream and downstream bandwidth on the Cisco CMTS

–CPU utilization and memory resources on the Cisco uBR10012 and Cisco uBR7246VXR router chassis (Cisco uBR10-MC5X20U and Cisco uBR-MC28U broadband processing engines)

•Admission Control does not support Wide Area Network (WAN) bandwidth monitoring for the Cisco uBR10012 router.

Information About Service Flow Admission Control

This section describes DOCSIS 1.1 concepts and configuration options supported on the Cisco CMTS for Service Flow Admission Control.

•Overview of Service Flow Admission Control for the Cisco CMTS, page 16-4

•Service Flow Admission Control and Cisco Universal Broadband Routers, page 16-5

•Service Flow Admission Control and Cisco CMTS Resources, page 16-5

•Service Flow Admission Control and CPU Utilization, page 16-6

•Service Flow Admission Control and Memory Utilization, page 16-6

•Service Flow Admission Control and Upstream or Downstream Bandwidth Utilization, page 16-7

•Comparing Service Flow Admission Control with Prior Admission Control, page 16-8

Overview of Service Flow Admission Control for the Cisco CMTS

SFAC on the Cisco CMTS is a mechanism that gracefully manages service flow admission requests when one or more resources are not available to process and support the incoming service request. Lack of such a mechanism not only causes the new request to fail with unexpected behavior but could potentially cause the flows that are in progress to have quality related problems. SFAC monitors such resources constantly, and accepts or denies requests depending on the resource availability.

SFAC enables you to provide a reasonable guarantee about the Quality of Service (QoS) to subscribers at the time of call admission, and to enable graceful degradation of services when resource consumption approaches critical levels. SFAC reduces the impact of unpredictable traffic demands in circumstances that would otherwise produce degraded QoS for subscribers.

SFAC uses two event types for resource monitoring and management—cable modem registration and dynamic service (voice call) requests. When either of these two events occurs on the Cisco CMTS, SFAC verifies that the associated resources conform to the configured limits prior to admitting and supporting the service call request.

SFAC is not a mechanism to apply QOS to the traffic flows. Scheduling and queuing are some of the mechanisms used for implementing the QOS. The QOS is applied on per packet basis. SFAC checks are performed before the flow is admitted.

SFAC in Cisco IOS Release 12.3(21)BC monitors the following resources on the Cisco CMTS.

•CPU utilization—SFAC monitors CPU utilization on the Cisco CMTS, and preserves QoS for existing service flows when new traffic would otherwise compromise CPU resources on the Cisco CMTS.

•Memory resource utilization (I/O, Processor, and combined total)—SFAC monitors one or both memory resources and their consumption, and preserves QoS in the same way as with CPU utilization.

•Bandwidth utilization for upstream and downstream—SFAC monitors upstream and downstream bandwidth utilization, and associated service classes, whether for data or dynamic service traffic.

Note See also the "Service Flow Admission Control and Cisco CMTS Resources" section on page 16-5.

Note SFAC begins graceful degradation of service when either a critical threshold is crossed, or when bandwidth is nearly consumed on the Cisco CMTS, depending on the resource being monitored.

SFAC enables you to configure major and minor thresholds for each resource on the Cisco CMTS. These thresholds are expressed in a percentage of maximum allowable resource utilization. Alarm traps may be sent each time a minor or major threshold is crossed for a given resource.

For system-level resources, such as CPU and memory utilization, you can configure critical thresholds in addition to the major and minor thresholds. When a critical threshold is crossed, further service requests are gracefully declined until the associated resource returns to a lower threshold level.

For upstream (US) and downstream (DS) channels, you can configure the bandwidth allocation with exclusive and non-exclusive thresholds. These thresholds can be configured for specified DOCSIS traffic types.

•Exclusive bandwidth indicates the percentage of bandwidth that is allocated exclusively for the specified traffic type. This bandwidth may not be shared with any other traffic type.

•Non-exclusive bandwidth indicates the percentage of bandwidth that is configured in addition to the exclusive bandwidth. Non-exclusive bandwidth is also configured for specific DOCSIS traffic types. Non-exclusive bandwidth is not guaranteed, and may be shared with other traffic types.

•The sum of exclusive and non-exclusive thresholds indicates the maximum bandwidth the specified traffic type may use.

This section provides additional information about SFAC with the following topics:

•Service Flow Admission Control and Cisco Universal Broadband Routers, page 16-5

•Service Flow Admission Control and Cisco CMTS Resources, page 16-5

•Service Flow Admission Control and CPU Utilization, page 16-6

•Service Flow Admission Control and Memory Utilization, page 16-6

•Service Flow Admission Control and Upstream or Downstream Bandwidth Utilization, page 16-7

Service Flow Admission Control and Cisco Universal Broadband Routers

Service Flow Admission Control on the Cisco uBR10012 Universal Broadband Router

Cisco IOS Release 12.3(21)BC supports Service Flow Admission Control on the Cisco uBR10012 router and all broadband processing engines.

Service Flow Admission Control on the Cisco uBR7246VXR Universal Broadband Router

Cisco IOS release 12.3(21)BC supports Service Flow Admission Control on the Cisco uBR7246VXR router.

Service Flow Admission Control and Memory Requirements for the Cisco CMTS

Service Flow Admission Control for the Cisco CMTS is a powerful feature that maintains Quality of Service (QoS) on the Cisco CMTS and enforces graceful degradation in service when attempted consumption exceeds resource availability.

Additional memory is required in the Cisco universal broadband router to maintain and store information about various scheduling types, the distribution of upstream or downstream traffic, and associated resource check processes. For complete information about memory requirements and Cisco IOS Release 12.3(21)BC, refer to the corresponding release notes for your product:

•Release Notes for Cisco uBR10012 Universal Broadband Router for Cisco IOS Release 12.3 BC

http://www.cisco.com/en/US/products/sw/iosswrel/ps5413/prod_release_note09186a0080326360.html

•Release Notes for Cisco uBR7200 Series for Cisco IOS Release 12.3 BC

http://www.cisco.com/en/US/products/sw/iosswrel/ps5413/prod_release_note09186a00803265f8.html

Service Flow Admission Control and Cisco CMTS Resources

Service Flow Admission Control with Cisco IOS Release 12.3(21)BC implements graceful QoS policies for the following resources of the Cisco CMTS:

System-Level Resources—Impact All Cisco CMTS Functions

•CPU utilization on route processor or broadband processing engine (BPE) modules

•I/O memory on route processor or broadband processing engine modules

•Processor memory

Bandwidth-Level Resources—Impact Traffic Per Interface or Per Port

•Downstream DOCSIS 1.1 bandwidth with QoS support on Cisco cable interface line cards or BPEs

•Upstream DOCSIS 1.1 bandwidth with QoS support on Cisco cable interface line cards or BPEs

Cisco IOS release 12.3(21)BC supports the following resources for the following Cisco CMTS routers:

Cisco uBR10012 Router Resources

•Cisco uBR Route Processor

–CPU Utilization

–Processor Memory

–I/O Memory

•Cisco uBR Cable Interface Line Card

–Downstream Bandwidth

–Upstream Bandwidth

Cisco uBR7246VXR Router Resources with the Cisco MC28U

•Cisco uBR Route Processor

–CPU Utilization

–Processor Memory

–I/O Memory

•Cisco uBR Cable Interface Line Card

–Downstream Bandwidth

–Upstream Bandwidth

Cisco uBR7246VXR Router Resources without the Cisco MC28U

•Network Processing Engine

–CPU Utilization

–Processor Memory

–I/O Memory

–Downstream Bandwidth

–Upstream Bandwidth

For additional information, refer to the "How to Configure, Monitor and Troubleshoot Service Flow Admission Control" section on page 16-9.

Service Flow Admission Control and CPU Utilization

CPU utilization is defined and monitored either as a five-second or a one-minute average. Both averages cannot be configured at the same time for any given resource. For CPU utilization, you can set minor, major, and critical threshold levels.

For additional information, refer to the "Configuring Service Flow Admission Control Based on CPU Utilization" section on page 16-12.

Service Flow Admission Control and Memory Utilization

Service Flow Admission Control can define up to three different memory options on the Cisco CMTS:

•IO memory - Current available (free) I/O memory

•Processor memory - Current available processor memory

•Both - Combined (IO and processor) memory that are available on the router

Memory resources are similar to CPU utilization, in that you can set minor, major, and critical threshold levels. Memory-based Service Flow Admission Control is supported for memory on the main CPU in Cisco IOS Release 12.3(21)BC, and not for the broadband processing engine line card memory.

For additional information, refer to the "Configuring Service Flow Admission Control Based on Memory Resources" section on page 16-13.

Service Flow Admission Control and Upstream or Downstream Bandwidth Utilization

Service Flow Admission Control allows you to control the bandwidth usage for various DOCSIS traffic types or application types. The application types are defined by the user using a CLI to categorize the service flow.

Categorization of Service Flows

The SFAC feature allows you to allocate the bandwidth based on the application types. Flow categorization allows you to partition bandwidth in up to eight application types or buckets. The composition of a bucket is defined by the command-line interface (CLI), as is the definition of rules to categorize service flows into one of these eight application buckets. Various attributes of the service flow may be used to define the rules.

For flows created by PacketCable, the following attributes may be used:

•the priority of the Packetcable gate associated with the flow (high or normal)

For flows created by PacketCable MultiMedia (PCMM), the following attributes may be used:

•Priority of the gate (0 to 7)

•Application type (0 to 65535)

The scheduling type for Upstream flows uses the following attribute type:

•Service class name

Before a service flow is admitted, it is passed through the categorization routine. Various attributes of the service flow are compared with the user-configured rules. Based on the match, the service flow is labeled with application type, from 1 to 8. The bandwidth allocation is then performed per application type.

Before a service flow is admitted, it is categorized based on its attributes. The flow attributes are compared against CLI-configured rules, one bucket at a time. If a match is found for any one of the rules, the service flow is labeled for that bucket, and no further check is performed.

Bucket 1 rules are scanned first and bucket 8 rules are scanned last. If two different rules match two different buckets for the same service flow, the flow gets categorized under the first match. If no match is found, the flow is categorized as Best Effort (BE) and the bucket with best effort rule is labelled to the flow. By default, the BE bucket is bucket 8.

Thresholds for Upstream or Downstream Bandwidth

SFAC monitors upstream or downstream bandwidth consumption with minor, major, and critical thresholds. SFAC generates alarm traps when bandwidth consumption crosses minor and major thresholds. For additional information, refer to the "How to Configure, Monitor and Troubleshoot Service Flow Admission Control" section on page 16-9.

Exclusive and Non-Exclusive Bandwidth Thresholds

In addition to minor and major thresholds, SFAC also allows configuration of exclusive or non-exclusive thresholds.

•Exclusive bandwidth thresholds, for the upstream or downstream bandwidth, define a given percentage of the total (100%) bandwidth, and dedicate it to a specific traffic type.

•Non-exclusive bandwidth thresholds can be shared with multiple traffic types. Non-exclusive bandwidth is typically used by Best Effort traffic, yet remains available to other traffic types when required.

When the traffic usage exceeds the exclusive threshold, SFAC checks if there is any non-exclusive bandwidth available. Any new service request is permitted only if sufficient non-exclusive bandwidth is available.

Comparing Service Flow Admission Control with Prior Admission Control

The prior Admission Control feature on the Cisco CMTS was introduced in Cisco IOS Release 12.3(13a)BC. This prior version of Admission Control allows you to set minor, major, exclusive and non-exclusive thresholds. This topic lists changes introduced for SFAC in Cisco IOS Release 12.3(21)BC, and identifies which part of the functionality is changed and which functionality is preserved.

Note The configuration, monitoring, and debugging commands used for the original Admission Control feature are not supported for the Service Flow Admission Control bucket scheme.

•SFAC retains the prior Admission Control concept of thresholds. SFAC enables configuration of major, minor, exclusive and non-exclusive thresholds. However, SFAC is distinct and unique in that the thresholds are applied per application bucket, numbered 1 to 8.

•For downstream service flows, the prior Admission Control feature permitted bandwidth allocation for only data and voice traffic, and only PacketCable voice was recognized. SFAC uniquely allows bandwidth allocation per application bucket. As with Admission Control, however, SFAC allocates bandwidth for PacketCable voice by configuring the appropriate rules that apply to the application buckets.

•Upstream bandwidth allocation in SFAC is not based on the scheduling types, such as UGS, RTPS and so forth. SFAC newly handles upstream channels in fashion similar to downstream channels—the upstream channels also support eight application types. You may configure SFAC bandwidth allocation based on the scheduling types. You achieve the same result, however, by defining the appropriate rules to map each scheduling type into one of the eight buckets.

•SFAC monitors and manages Cisco CMTS resources according to the categorization of service flow, in which service flow policies, status and resource management are configured and processed in more categorical fashion, to include support for both PacketCable and PacketCable MultiMedia voice traffic.

•SFAC newly treats upstream and downstream traffic in the same manner and in more uniform fashion than the previous Admission Control feature.

•Exclusive and non-exclusive thresholds define resource management processes of the SFAC feature.

•Service Flow Admission Control introduces enhanced support for the CISCO-CABLE-ADMISSION-CTRL-MIB.

How to Configure, Monitor and Troubleshoot Service Flow Admission Control

This section describes the following configuration, monitoring and troubleshooting procedures for the Service Flow Admission Control (SFAC) feature. Configuration procedures are optional, given default configurations are enabled in Cisco IOS Release 12.3(21)BC. This section presents a sequence of procedures for non-default configurations, monitoring and debugging procedures that apply in default or non-default operations of Service Flow Admission Control.

Primary Configurations for Service Flow Admission Control

•Enabling Service Flow Admission Control for Event Types, page 16-10

This procedure sets the events that trigger the Admission Control checks on the Cisco CMTS.

•Configuring Service Flow Admission Control Based on CPU Utilization, page 16-12

This procedure configures threshold levels for CPU utilization. When threshold levels are crossed during an Admission Control check, an alarm is generated or the service is gracefully declined, depending on the level crossed.

•Configuring Service Flow Admission Control Based on Memory Resources, page 16-13

This procedure configures memory resource types and associated threshold levels for Admission Control on the Cisco CMTS.

•Defining Rules for Service Flow Categorization, page 16-14

This procedure describes how to configure service flow rules on the Cisco CMTS. This procedure changes default global service flow rule rules. By default, Cisco IOS Release 12.3(21)BC enables the definition of service flows according to application or traffic type, with bucket assignments for a standard set of service flow applications.

•Naming Application Buckets for Service Flow Admission Control, page 16-19

This procedure enables you to assign alpha-numeric names to six of the eight application buckets that Service Flow Admission Control supports.

•Setting Downstream and Upstream Application Thresholds, page 16-21

This procedure sets downstream and upstream applications thresholds for Service Flow Admission Control on the Cisco CMTS.

•Preempting High-Priority Emergency 911 Calls, page 16-25

This procedure enables you to override the default Emergency 911 call preemption functions described in the "Comparing Service Flow Admission Control with Prior Admission Control" section on page 16-8.

•Calculating Upstream and Downstream Bandwidth Utilization, page 16-27

Provides guidelines for calculating requirements and potential configurations of Service Flow Admission Control and related thresholds and settings.

Monitoring and Troubleshooting Commands for Service Flow Admission Control

•Bandwidth Validity Checks for Service Flow Admission Control, page 16-28

Provides guidelines for performing validation of configuration and operation.

•Displaying Application Buckets for Service Flow Admission Control, page 16-29

Describes how to display the application types configured and active.

•Displaying Service Flow Reservation Levels, page 16-30

Describes how to display the reservation levels configured and active.

•Displaying SFAC Configuration and Status, page 16-31

Describes how to display service flows, application categorizations, and bandwidth consumption status.

•Debugging Service Flow Admission Control for Different Event Types, page 16-33

Describes how to debug event type classifications.

•Debugging Service Flow Admission Control for CPU Resources, page 16-34

Describes how to debug CPU resource configurations.

•Debugging Service Flow Admission Control for Downstream Bandwidth, page 16-36

Describes how to debug downstream bandwidth settings and operation.

•Debugging Service Flow Admission Control for Upstream Throughput, page 16-37

Describes how to debug upstream throughput settings and operation.

•Debugging Flow Categorization for Service Flow Admission Control, page 16-38

Describes how to enable and use debug and show commands for service flow categorization settings.

Enabling Service Flow Admission Control for Event Types

Service Flow Admission Control can be enabled for one or more of the following events. At least one of these events must be configured for Service Flow Admission Control on the Cisco CMTS prior to the configuration of any additional settings:

•the registration of a cable modem

•the request for a dynamic service, such as a PacketCable or PCMM voice call

Perform these steps to configure either or both event types on the Cisco CMTS.

Prerequisites

Service Flow Admission Control requires that event types, traffic types and CMTS resource thresholds be configured and enabled on the Cisco CMTS. Refer also to the "Prerequisites for Service Flow Admission Control" section on page 16-2.

SUMMARY STEPS

1. enable

2. configure terminal

3. cable admission-control event { cm-registration | dynamic-service }

4. Ctrl-Z

DETAILED STEPS

 
Command or Action
Purpose

Step 1 

enable

Example:

Router> enable

Enables privileged EXEC mode.

•Enter your password if prompted.

Step 2 

configure terminal

Example:

Router# configure terminal

Enters global configuration mode.

Step 3 

cable admission-control event { cm-registration | dynamic-service }

Example:

Router(config)# cable admission-control event cm-registration

Router(config)# cable admission-control event dynamic-service


Sets the event type on the Cisco CMTS at which Service Flow Admission Control performs resource monitoring and management. At least one of the following keywords must be used, and both can be set.

•cm-registration—Sets Service Flow Admission Control checks to be performed when a cable modem registers. If there are insufficient resources at the time of registration, the cable modem is allowed to come online.

•dynamic-service—Sets Service Flow Admission Control checks to be performed when a dynamic service such as a voice call is requested.

Step 4 

Ctrl-Z

Example:

Router(config-if)# Ctrl^Z

Returns to Privileged EXEC mode.

Examples

The following example in global configuration mode enables both event types on the Cisco CMTS:

Router(config)# cable admission-control event cm-registration

Router(config)# cable admission-control event dynamic-service


What to Do Next

Once configured, event types and Service Flow Admission Control event activity on the Cisco CMTS can be reviewed using the following two commands:

•debug cable admission-control options

•show cable admission-control

If the resources to be monitored and managed by Service Flow Admission Control are not yet configured on the Cisco CMTS, refer to the additional procedures in this document for information about their configuration.

Configuring Service Flow Admission Control Based on CPU Utilization

Service Flow Admission Control allows you to configure minor, major and critical thresholds for CPU utilization. The thresholds are specified as percentage of CPU utilization. When the an event such as cable modem registration or dynamic service takes place, and the CPU utilization is greater than the major or minor threshold, an alarm is generated. If it is greater than the critical threshold, the new service is gracefully declined.

Service Flow Admission Control enforces threshold levels in one of two ways. The Cisco CMTS supports both enforcement methods, but both cannot be configured at the same time.

•cpu-5sec—This finest-level setting configures the Cisco CMTS to reject new requests when the cpu-5sec utilization has exceeded the configured critical threshold. This protects any time-sensitive activities on the router. Service Flow Admission Control takes action on the router when a new request might otherwise exceed the configured CPU threshold level.

•cpu-avg—This normal-level setting is a CPU utilization average, enforced by sampling the CPU utilization at much lower frequency and calculating an exponentially weighted average. Service Flow Admission Control takes action on the router when a new service request might otherwise exceed the configured CPU peak threshold level.

Prerequisites

Refer to the "Prerequisites for Service Flow Admission Control" section on page 16-2.

SUMMARY STEPS

1. enable

2. configure terminal

3. cable admission-control {cpu-5sec | cpu-avg } minor num1 major num2 critical num3

4. Ctrl-Z

DETAILED STEPS

 
Command or Action
Purpose

Step 1 

enable

Example:

Router> enable

Enables privileged EXEC mode.

•Enter your password if prompted.

Step 2 

configure terminal

Example:

Router# configure terminal

Enters global configuration mode.

Step 3 

[no] cable admission-control {cpu-5sec | cpu-avg } minor num1 major num2 critical num3

Example:

Router# cable admission-control cpu-avg minor 60 major 70 critical 80

Configures CPU memory thresholds on the Cisco CMTS for Service Flow Admission Control.

•cpu-5sec—average CPU utilization over a period of five seconds.

•cpu-avg—average CPU utilization over a period of one minute.

•minor num1—Specifies the minor threshold level, where num1 is a percentage and can be an integer between 1 and 100.

•major num2—Specifies the major threshold level, where num2 is a percentage and can be an integer between 1 and 100.

•critical num3—Specifies the critical threshold level, where num3 is a percentage and can be an integer between 1 and 100.

There are no default values for this command.

Note cpu-5sec and cpu-avg cannot be configured at the same time.

Step 4 

Ctrl-Z

Example:

Router(config-if)# Ctrl^Z

Returns to Privileged EXEC mode.

Note When the minor value (num1) is crossed, then an alarm (trap) is sent. When the major value (num2) is crossed, then another alarm (trap) is sent. When the critical value (num3) is crossed, then the request is gracefully declined.

Note The threshold counters are set to zero when the resource is re-configured.

Note The minor threshold should be less than the major threshold, and the major threshold must be less than the critical threshold.

Configuring Service Flow Admission Control Based on Memory Resources

Three different memory resource options can be configured on the Cisco CMTS:

•IO memory - Current available (free) I/O memory

•Processor memory - Current available processor memory

•Both - Combined (IO and processor) memory that are available on the router

Memory-based Service Flow Admission Control is supported for memory on the main CPU in Cisco IOS Release 12.3(21)BC, and not for the broadband processing engine line card memory. As with CPU utilization, you can set minor, major, and critical threshold levels.

Prerequisites

Refer to the "Prerequisites for Service Flow Admission Control" section on page 16-2.

SUMMARY STEPS

1. enable

2. configure terminal

3. cable admission-control { io-mem | proc-mem | total-memory } minor num1 major num2 critical num3

4. Ctrl-Z

DETAILED STEPS

 
Command or Action
Purpose

Step 1 

enable

Example:

Router> enable

Enables privileged EXEC mode.

•Enter your password if prompted.

Step 2 

configure terminal

Example:

Router# configure terminal

Enters global configuration mode.

Step 3 

[no] cable admission-control { io-mem | proc-mem | total-memory } minor num1 major num2 critical num3

Example:

Router# need two new examples

Configures CPU memory thresholds on the Cisco router.

•io-mem—Input/Output memory on the Cisco router

•proc-mem—Process memory on the Cisco router

•total-memory—Combined I/O and processor memory on the CMTS

•minor num1—Specifies the minor threshold level, where num1 is a percentage and can be an integer between 1 and 100.

•major num2—Specifies the major threshold level, where num2 is a percentage and can be an integer between 1 and 100.

•critical num3—Specifies the critical threshold level, where num3 is a percentage and can be an integer between 1 and 100.

There are no default values for this command.

Note All three memory threshold levels can and should be configured.

Step 4 

Ctrl-Z

Example:

Router(config-if)# Ctrl^Z

Returns to Privileged EXEC mode.

Note When the minor value (num1) is crossed, then an alarm (trap) is sent. When the major value (num2) is crossed, then another alarm (trap) is sent. When the critical value (num3) is crossed, then the request is gracefully declined.

Note The threshold counters are set to zero when the resource is re-configure.

Defining Rules for Service Flow Categorization

This procedure describes how to configure service flow categorization rules on the Cisco CMTS. This flexible procedure changes default global service flow rules with variations of the cable application type include command.

By default, Cisco IOS Release 12.3(21)BC enables the definition of service flows according to application or traffic type, with bucket assignments for a standard set of service flow applications.

Any one or several of these steps or commands may be used, in nearly any combination, to set or re-configure SFAC on the Cisco CMTS.

Note Application rules for Service Flow Admission Control are global configurations, and upstream and downstream bandwidth resources use the same sets of service flow rules.

SUMMARY STEPS

1. enable

2. configure terminal

3. cable application-type n include packetcable { normal | priority }

4. cable application-type n include pcmm { priority gate-priority | app-id gate-app-id }

5. cable application-type n include scheduling-type type

6. cable application-type n include service-class service-class-name

7. cable application-type n include BE

8. Ctrl-Z

DETAILED STEPS

 
Command or Action
Purpose

Step 1 

enable

Example:

Router> enable

Enables privileged EXEC mode.

•Enter your password if prompted.

Step 2 

configure terminal

Example:

Router# configure terminal

Router(config)#

Enters global configuration mode.

Step 3 

cable application-type n include packetcable { normal | priority }

Example:

Router(config)# cable application-type 5 include packetcable priority


For PacketCable, this command variation maps PacketCable service flow attributes to the specified bucket. PacketCable service flows are associated with PacketCable gates. The gate can be normal or high-priority.

•n—Specify the bucket number to which an application is associated, with range from 1 to 8, with 1 as the first in the sequence.

•packetcable—Specifies PacketCable for the designated bucket, with the associated priority configured with additional keywords.

•normal—Maps normal PacketCable service flows into the specified application bucket.

•priority—Maps high-priority PacketCable service flows into the specified application bucket.

Step 4 

cable application-type n include pcmm { priority gate-priority | app-id gate-app-id }

Example:

Router(config)# cable application-type 2 include pcmm priority 7


Router(config)# cable application-type 2 include pcmm app-id 152

For PCMM, this command variation maps PCMM service flow priority or application to the specified bucket. The PCMM gates are characterized by a priority level and by an application identifier.

•n—Specify the bucket number to which an application is associated, with range from 1 to 8, with 1 as the first in the sequence.

•pcmm—Specifies PCMM for the designated bucket, with the associated priority and applications configured with additional keywords.

•priority gate-priority—Designates the priority level for PCMM in this bucket. The priority level can range from 0 to 7.

•app-id gate-app-id—Designates the application identifier for PCMM in this bucket. The application identifier can be from 0 to 65535. For each bucket, up to 10 application type rules may be defined.

Step 5 

cable application-type n include scheduling-type type

Example:

Router(config)# cable application-type 1 include scheduling-type ugs


Router(config)# cable application-type 1 include scheduling-type ugs-ad


For DOCSIS scheduling types, this command variation binds the DOCSIS scheduling types into the designated application bucket. DOCSIS 1.1 specifies the scheduling type to bind QoS parameters to the service flows for upstream traffic.

•n—Specify the bucket number to which an application is associated, with range from 1 to 8, with 1 as the first in the sequence.

•scheduling-type—Keyword applies this command to upstream scheduling types, as further defined with one of the following additional keywords.

•type—Choose one of the DOCSIS scheduling types:

–UGS—Unsolicited Grant Service

–UGS-AD—UGS-AD service

–RTPS—real-time polling service

–nRTPS—non-real-time polling service

–BE—Best Effort

Step 6 

cable application-type n include service-class service-class-name

Example: 
Router(config)# cable application-type 1 
include service-class upstream1

For service class parameters, this command variation applies a service class name to the service flows, and applies corresponding QoS parameters.

•n—Specify the bucket number to which an application is associated, with range from 1 to 8, with 1 as the first in the sequence.

•service-class —Keyword applies this command to the service class being assigned to the designated bucket.

•service-class-name—Alphanumeric service class name.

DOCSIS 1.1 introduced the concept of service classes. A service class is identified by a service class name. A Service Class Name is a string which the CMTS associates with a QOS Parameter Set. One of the objectives of using a service class is to allow the high level protocols to create the service flows with desired QOS parameter set. Using a service class is a convenient way to bind the application with the service flows. The rules provide a mechanism to implement such binding.

Note the following factors when using the command in this step:

•Service classes are separately configured using the cable service class command to define the service flow.b

•A named service class may be classified into any application type.

•Up to ten service class names may be configured per application types. Attempting to configure more than ten service classes prints an error message.

•Using the no cable traffic-type command, remove configuration of one of the service class names before adding a new class.

Step 7 

Router(config)# cable application-type n include BE

Example:

Router# cable application-type 3 include BE

For Best Effort service flows, this command variation elaborates on Step 3, and changes the default bucket of 8 for Best Effort service flows with non-zero Committed Information Rate (CIR). These BE service flows are often created during cable modem registration.

•n—Specify the bucket number to which an application is associated, with range from 1 to 8, with 1 as the first in the sequence.

•BE—Keyword applies Best Effort CIR to the specified bucket.

Note that there is an alternate rule that applies to the Best Effort scheduling type. This rule is applicable only for upstream service flows, as described in an earlier step of this procedure.

The BE CIR service flow rule may be applicable to both upstream and downstream. However, in the case of upstream service flows, in most cases, the same service flow may map both the rules.

Step 8 

Ctrl-Z

Example:

Router(config)# Ctrl^Z

Router#

Returns to Privileged EXEC mode.

Examples

The following example maps high-priority PacketCable service flows into application bucket 5. 

Router(config)# cable application-type 5 include packetcable priority

The following example maps normal PacketCable service flows into application bucket 1. 

Router(config)# cable application-type 1 include packetcable normal

The following example maps the specified bucket number with PCMM service flow with a priority of 7, then maps an application identifier of 152 for the same bucket number: 

Router(config)# cable application-type 2 include pcmm priority 7 

Router(config)# cable application-type 2 include pcmm app-id 152

The following example maps both UGS and UGS-AD into bucket number 1: 

Router(config)# cable application-type 1 include scheduling-type ugs 

Router(config)# cable application-type 1 include scheduling-type ugs-ad

The following example maps the Best Effort CIR flows to bucket 3: 

Router(config)# cable application-type 3 include BE

Troubleshooting Tips

Service Flow Admission Control supports debug and show commands for monitoring and troubleshooting functions on the Cisco CMTS. Refer to the following procedures:

•Displaying Application Buckets for Service Flow Admission Control

•Displaying Service Flow Reservation Levels

•Debugging Flow Categorization for Service Flow Admission Control

What to Do Next

When rules for Service Flow Admission Control are enabled on the Cisco CMTS, which is the default, those rules can be overridden or re-configured with the steps in this procedure. Once rules are enabled, the application buckets can be named or renamed with the procedure in the "Naming Application Buckets for Service Flow Admission Control" section on page 16-19.

Otherwise, refer to additional non-default procedures in this document, or to the following procedures for monitoring or troubleshooting Service Flow Admission Control on the Cisco CMTS:

•Displaying Application Buckets for Service Flow Admission Control

•Displaying Service Flow Reservation Levels

•Debugging Flow Categorization for Service Flow Admission Control

Naming Application Buckets for Service Flow Admission Control

This procedure enables you to assign alpha-numeric names to six of the eight application buckets that Service Flow Admission Control supports. The default bucket identifiers range from 1 to 8.

SUMMARY STEPS

1. enable

2. configure terminal

3. cable application-type n name bucket-name

4. Ctrl-Z

DETAILED STEPS

 
Command or Action
Purpose

Step 1 

enable

Example:

Router> enable

Enables privileged EXEC mode.

•Enter your password if prompted.

Step 2 

configure terminal

Example:

Router# configure terminal

Router(config)#

Enters global configuration mode.

Step 3 

cable application-type n name bucket-name

Example:

Router(config)# cable application-type 7 name besteffort


Assigns an alpha-numeric name for the specified bucket.

Note This bucket name appears in supporting show and debug commands along with the default bucket number.

•n—Specify the bucket number to which the name is applied. The priority sequence of the buckets, according to their original numeration of 1 to 8, still applies, whether the default bucket numbers or customized alpha-numeric names are used.

•name—Keyword enables bucket renaming to the value specified.

•bucket-name—Alpha-numeric bucket name to augment the default bucket number and display in show commands.

Step 4 

Ctrl-Z

Example:

Router(config)# Ctrl^Z

Returns to Privileged EXEC mode.

Examples

The following example illustrates the use of descriptive names instead of numeration for the associated buckets: 

Router(config)# cable application-type 2 name video 

Router(config)# cable application-type 3 name gaming

The change made with this procedure is displayed with the show application-buckets command.

Troubleshooting Tips

Service Flow Admission Control supports debug and show commands for monitoring and troubleshooting functions on the Cisco CMTS. Refer to the following procedures:

•Displaying Application Buckets for Service Flow Admission Control

•Displaying Service Flow Reservation Levels

•Debugging Flow Categorization for Service Flow Admission Control

What to Do Next

The change made with this procedure is displayed with the show application-buckets command.

Refer to additional non-default procedures in this document, or to the following procedures for monitoring or troubleshooting Service Flow Admission Control on the Cisco CMTS:

•Displaying Application Buckets for Service Flow Admission Control

•Displaying Service Flow Reservation Levels

•Debugging Flow Categorization for Service Flow Admission Control

Setting Downstream and Upstream Application Thresholds

This procedure sets downstream and upstream applications thresholds for Service Flow Admission Control on the Cisco CMTS. This procedure extends the previous Admission Control commands from earlier Cisco IOS releases to support additional applications in Service Flow Admission Control. The settings in this procedure may be applied in either global or per-interface mode for downstream and upstream applications, and may also be applied in per-upstream fashion if desired.

Precedence of These Configuration Commands

Service Flow Admission Control based on bandwidth can be configured at the interface or global level. For upstream bandwidth, SFAC can be configured at the per-upstream