Khác biệt giữa bản sửa đổi của “MIME”
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Table Of Contents |
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QoS Bandwidth Estimation |
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Contents |
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Prerequisites for QoS Bandwidth Estimation |
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Restrictions for QoS Bandwidth Estimation |
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Information About QoS Bandwidth Estimation |
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Feature Overview of QoS Bandwidth Estimation |
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Applying Corvil Bandwidth |
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Benefits of QoS Bandwidth Estimation |
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How to Configure QoS Bandwidth Estimation |
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Generating a Bandwidth Estimate |
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Attaching the Policy Map to an Interface |
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Restrictions |
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Verifying the Configuration |
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Configuration Examples for QoS Bandwidth Estimation |
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Generating Bandwidth Estimates for QoS Targets: Example |
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Attaching the Policy Map to an Interface: Example |
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Verifying the Configuration: Example |
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Additional References |
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Related Documents |
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Standards |
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MIBs |
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RFCs |
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Technical Assistance |
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Feature Information for QoS Bandwidth Estimation |
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Glossary |
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QoS Bandwidth Estimation |
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First Published: March 29, 2005 |
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Last Updated: April 30, 2007 |
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The QoS Bandwidth Estimation feature uses Corvil Bandwidth technology to allow you, as a network manager, to determine the bandwidth requirements to achieve user-specified quality of service (QoS) targets for networked applications. |
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Finding Feature Information in This Module |
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Your Cisco IOS software release may not support all of the features documented in this module. For the latest feature information and caveats, see the release notes for your platform and software release. 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 "Feature Information for QoS Bandwidth Estimation" section. |
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Finding Support Information for Platforms and Cisco IOS and Catalyst OS Software Images |
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Use Cisco Feature Navigator to find information about platform support and Cisco IOS and Catalyst OS software image support. To access Cisco Feature Navigator, go to http://www.cisco.com/go/cfn. An account on Cisco.com is not required. |
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Contents |
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•Prerequisites for QoS Bandwidth Estimation |
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•Restrictions for QoS Bandwidth Estimation |
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•Information About QoS Bandwidth Estimation |
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•How to Configure QoS Bandwidth Estimation |
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•Configuration Examples for QoS Bandwidth Estimation |
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•Additional References |
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•Feature Information for QoS Bandwidth Estimation |
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•Glossary |
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Prerequisites for QoS Bandwidth Estimation |
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•Before using this feature, configure a class map and a policy map using the Modular Quality of Service (QoS) Command-Line Interface (CLI) (MQC), and specify the appropriate match criteria. |
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•This feature requires the purchase of a Cisco IOS software feature license. The right to use this feature is not included in the base Cisco IOS software license for the software image. |
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Restrictions for QoS Bandwidth Estimation |
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This feature supports policy maps that are attached to interfaces in an output direction only. |
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Information About QoS Bandwidth Estimation |
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To use the QoS Bandwidth Estimation feature, you should understand the following concepts: |
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•Feature Overview of QoS Bandwidth Estimation |
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•Benefits of QoS Bandwidth Estimation |
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Feature Overview of QoS Bandwidth Estimation |
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Allocating adequate bandwidth is key to ensuring the network performance required for applications. However, allocating too much bandwidth can be costly. The QoS Bandwidth Estimation feature in Cisco IOS software uses Corvil Bandwidth technology to allow you, as a network manager, to determine the bandwidth requirements to achieve user-specified quality of service (QoS) targets for networked applications. |
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Corvil Bandwidth can determine the minimum bandwidth required to deliver traffic within customer-specified QoS targets with statistical reliability. From a network management perspective, an application's QoS requirements are characterized with respect to its sensitivity to delay and packet loss. Corvil Bandwidth provides a way to specify limits for delay and packet loss, and get a tight estimate of the minimum bandwidth essential to achieve desired application performance. |
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Corvil Bandwidth achieves its results by taking very short timescale (8-millisecond) snapshots of traffic and summarizing them in traffic descriptors that place very low overhead on the router because each descriptor has fewer than 300 bytes. These traffic descriptors record the exceptional events (bursts) and are input to the Corvil Bandwidth algorithm to calculate the minimum bandwidth required to deliver the user-specified QoS target for the observed traffic. (The QoS target is specified in terms of sensitivity to traffic delay and packet loss. For example, voice over IP [VoIP] traffic is very sensitive to both, whereas e-mail file transfer is sensitive to neither.) |
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As a result, turning on Corvil Bandwidth in the router allows you to obtain bandwidth values that can be used directly to configure the existing Cisco IOS QoS mechanisms on the router to achieve the required application performance as efficiently as possible. |
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For example, in Figure 1, Corvil Bandwidth is enabled on the router so that the serial interface can deliver the WAN traffic within the customer-specified QoS targets with statistical reliability. |
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Figure 1 Sample Topology Using QoS Bandwidth Estimation |
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Applying Corvil Bandwidth |
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The following sections describe how Corvil Bandwidth can be implemented: |
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•Link Sizing |
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•Bandwidth Allocations by Traffic Class |
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Link Sizing |
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To use Corvil Bandwidth to establish the overall bandwidth requirement for a link, you start with QoS targets appropriate for the speed of the link and for the applications being carried on the link (Figure 2). The QoS targets are achieved as long as the link capacity is greater than or equal to the computed Corvil Bandwidth value. |
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Figure 2 Link Sizing |
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Bandwidth Allocations by Traffic Class |
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Corvil Bandwidth can be used to size bandwidth allocations for individual traffic classes defined via the MQC (Figure 3). You specify the QoS target for a traffic class, and Corvil Bandwidth reports the minimum amount of bandwidth that must be allocated to meet that target. The Corvil Bandwidth value can be used directly in the corresponding MQC policy. (The bandwidth allocation is not changed automatically.) |
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Figure 3 Bandwidth Allocations |
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Benefits of QoS Bandwidth Estimation |
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Table 1 shows the features and benefits of QoS Bandwidth Estimation using Corvil Bandwidth technology. |
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Table 1 QoS Bandwidth Estimation |
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Feature |
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Benefits |
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User-specified packet loss and delay targets |
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•Establishment of service-level objectives for the desired performance of networked applications |
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•Elimination of operational overhead and guesswork in bandwidth provisioning and QoS configuration |
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•Potentially significant bandwidth cost savings while meeting QoS requirements |
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•Increased capability and flexibility to offer bandwidth-on-demand types of services |
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Frequent fine-grain traffic measurements |
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•More accurate calculation of bandwidth requirements |
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•Greater ability to meet more stringent QoS targets |
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Support for multiple traffic classes on an interface |
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•Individually specified QoS targets for each traffic class (class map) to calculate Corvil Bandwidth values |
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Corvil Bandwidth integrated with MQC |
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•Results available by traffic class |
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•Bandwidth adjustment enabled in the corresponding MQC-based policy |
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Corvil Bandwidth results reported in kbps |
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•Results directly applied via Cisco IOS MQC bandwidth command and to link-rate sizing |
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Corvil Bandwidth results available in class-based QoS MIB |
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•Integrated with Simple Network Management Protocol (SNMP)-based performance management tools |
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Low resource consumption on router |
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•Efficient to use, adding little additional processing or memory requirements |
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Available on any router interface |
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•Applicable to serial, T1/E1, Fast Ethernet, and other interfaces, as well as ATM virtual circuits (VCs), Frame Relay permanent virtual circuits (PVCs), multilink bundle interfaces, and virtual LAN (VLAN) subinterfaces |
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How to Configure QoS Bandwidth Estimation |
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This section contains the following procedures: |
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•Generating a Bandwidth Estimate (required) |
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•Attaching the Policy Map to an Interface (required) |
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•Verifying the Configuration (optional) |
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Generating a Bandwidth Estimate |
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To generate a bandwidth estimate, perform the following task. |
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SUMMARY STEPS |
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1. enable |
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2. configure terminal |
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3. policy-map policy-map-name |
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4. class [class-name | class-default] |
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5. bandwidth [bandwidth-kbps | remaining percent percentage | percent percentage] |
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6. estimate bandwidth [drop-one-in n] [delay-one-in n milliseconds n] |
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7. end |
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DETAILED STEPS |
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Command or Action |
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Purpose |
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Step 1 |
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enable |
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Example: |
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Router> enable |
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Enables privileged EXEC mode. |
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•Enter your password if prompted. |
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Step 2 |
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configure terminal |
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Example: |
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Router# configure terminal |
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Enters global configuration mode. |
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Step 3 |
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policy-map policy-map-name |
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Example: |
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Router(config)# policy-map my-policy |
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Specifies the name of the policy map to be created. Enters policy-map configuration mode. |
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•Enter the policy-map name. |
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Step 4 |
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class [class-name | class-default] |
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Example: |
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Router(config-pmap)# class my-class |
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Specifies the class so that you can configure or modify its policy. Enters policy-map class configuration mode. |
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•Enter the class name or use the class-default keyword. |
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Step 5 |
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bandwidth [bandwidth-kbps | remaining percent percentage | percent percentage] |
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Example: |
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Router(config-pmap-c)# bandwidth percent 20 |
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Specifies or modifies the bandwidth allocated for a class belonging to a policy map. |
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•Enter the bandwidth to be set or modified. |
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Step 6 |
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estimate bandwidth [drop-one-in n] [delay-one-in n milliseconds n] |
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Example: |
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Router(config-pmap-c)# estimate bandwidth drop-one-in 100 delay-one-in 100 milliseconds 50 |
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(Optional) Estimates the bandwidth needed per traffic class for given quality of service (QoS) targets based on traffic data. |
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•Enter values for the packet loss target, the delay target, and the delay threshold. |
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Step 7 |
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end |
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Example: |
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Router(config-pmap-c)# end |
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(Optional) Exits policy-map class configuration mode. |
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Attaching the Policy Map to an Interface |
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To attach the policy map to an interface, perform the following task. |
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Restrictions |
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This feature supports policy maps attached to an interface in the output direction only. |
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SUMMARY STEPS |
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1. enable |
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2. configure terminal |
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3. interface type number [name-tag] |
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4. service-policy {input | output} policy-map-name |
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5. end |
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DETAILED STEPS |
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Command or Action |
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Purpose |
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Step 1 |
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enable |
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Example: |
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Router> enable |
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Enables privileged EXEC mode. |
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•Enter your password if prompted. |
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Step 2 |
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configure terminal |
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Example: |
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Router# configure terminal |
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Enters global configuration mode. |
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Step 3 |
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interface type number [name-tag] |
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Example: |
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Router(config)# interface fastethernet0/1 |
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Configures the specified interface and enters interface configuration mode. |
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•Enter interface type and number. |
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Step 4 |
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service-policy {input | output} policy-map-name |
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Example: |
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Router(config-if)# service-policy output |
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my-policy |
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Specifies the name of the policy map to be attached to the interface. |
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Note You can configure policy maps on ingress or egress routers and attach them in the input or output direction of an interface. The direction (input or output) and the router (ingress or egress) to which the policy map should be attached vary according to your network configuration. For this feature, only the output direction is supported. |
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•Enter the output keyword followed by the policy map name. |
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Step 5 |
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end |
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Example: |
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Router(config-if)# end |
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(Optional) Exits interface configuration mode. |
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Verifying the Configuration |
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To verify that bandwidth estimates have been generated, perform the following task. |
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SUMMARY STEPS |
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1. enable |
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2. show policy-map interface interface-name [vc [vpi/] vci] [dlci dlci] [input | output] |
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3. exit |
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DETAILED STEPS |
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Command or Action |
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Purpose |
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Step 1 |
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enable |
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Example: |
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Router> enable |
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Enables privileged EXEC mode. |
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•Enter your password if prompted. |
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Step 2 |
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show policy-map interface interface-name [vc [vpi/]vci][dlci dlci][input | output] |
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Example: |
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Router# show policy-map interface fastethernet0/1 |
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Displays the packet statistics of all classes that are configured for all service policies either on the specified interface or subinterface or on a specific PVC on the interface. |
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•Enter the interface name. |
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Step 3 |
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exit |
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Example: |
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Router# exit |
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(Optional) Exits privileged EXEC mode. |
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Configuration Examples for QoS Bandwidth Estimation |
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This section contains the following configuration examples: |
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•Generating Bandwidth Estimates for QoS Targets: Example |
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•Attaching the Policy Map to an Interface: Example |
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•Verifying the Configuration: Example |
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Generating Bandwidth Estimates for QoS Targets: Example |
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In the following example, a policy map and a traffic class are configured. Then bandwidth estimates for QoS targets including packet loss rate, delay time and probability, and timeframe in milliseconds are configured. |
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Router# configure terminal |
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Router(config)# policy-map my-policy |
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Router(config-pmap)# class my-class |
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Router(config-pmap-c)# bandwidth percent 20 |
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Router(config-pmap-c)# estimate bandwidth drop-one-in 100 delay-one-in 100 milliseconds 50 |
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Router(config-pmap-c)# end |
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Attaching the Policy Map to an Interface: Example |
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The following example shows the policy map named my-policy being attached to Fast Ethernet interface 0/1 in the output direction: |
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Router# configure terminal |
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Router(config)# interface f0/1 |
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Router(config-if)# service-policy output my-policy |
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Router(config-if)# exit |
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Verifying the Configuration: Example |
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The following example from the show policy-map interface command verifies that the policy map named my-policy is attached to Fast Ethernet interface 0/1 in the output direction and that bandwidth estimates have been created: |
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Router# show policy-map interface fastethernet0/1 |
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FastEthernet0/1 |
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Service-policy output: my-policy |
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Class-map: icmp (match-all) |
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199 packets, 22686 bytes |
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30 second offered rate 0 bps, drop rate 0 bps |
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Match: access-group 101 |
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Bandwidth Estimation: |
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Quality-of-Service targets: |
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drop no more than one packet in 1000 (Packet loss < 0.10%) |
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delay no more than one packet in 100 by 40 (or more) milliseconds |
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(Confidence: 99.0000%) |
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Corvil Bandwidth: 1 kbits/sec |
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Class-map: class-default (match-any) |
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112 packets, 14227 bytes |
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30 second offered rate 0 bps, drop rate 0 bps |
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Match: any |
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Bandwidth Estimation: |
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Quality-of-Service targets: |
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<none specified, falling back to drop no more than one packet in 500 |
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Corvil Bandwidth: 1 kbits/sec |
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Additional References |
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The following sections provide references related to the QoS Bandwidth Estimation feature. |
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Related Documents |
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Related Topic |
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Document Title |
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QoS commands: complete command syntax, command modes, command history, defaults, usage guidelines, and examples |
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Cisco IOS Quality of Service Solutions Command Reference |
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Information about attaching policy maps to interfaces using the MQC |
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"Applying QoS Features Using the MQC" module |
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Standards |
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Standard |
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Title |
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No new or modified standards are supported, and support for existing standards has not been modified. |
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— |
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MIBs |
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MIB |
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MIBs Link |
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•CISCO-CLASS-BASED-QOS-MIB |
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•CISCO-CLASS-BASED-QOS-CAPABILITY-MIB |
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To locate and download MIBs for selected platforms, Cisco IOS releases, and feature sets, use Cisco MIB Locator found at the following URL: |
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http://www.cisco.com/go/mibs |
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RFCs |
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RFC |
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Title |
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No new or modified RFCs are supported, and support for existing RFCs has not been modified. |
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— |
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Technical Assistance |
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Description |
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Link |
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The Cisco Support website provides extensive online resources, including documentation and tools for troubleshooting and resolving technical issues with Cisco products and technologies. |
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To receive security and technical information about your products, you can subscribe to various services, such as the Product Alert Tool (accessed from Field Notices), the Cisco Technical Services Newsletter, and Really Simple Syndication (RSS) Feeds. |
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Access to most tools on the Cisco Support website requires a Cisco.com user ID and password. |
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http://www.cisco.com/techsupport |
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Feature Information for QoS Bandwidth Estimation |
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Table 2 lists the release history for this feature. |
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Not all commands may be available in your Cisco IOS software release. For release information about a specific command, see the command reference documentation. |
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Use Cisco Feature Navigator to find information about platform support and software image support. Cisco Feature Navigator enables you to determine which Cisco IOS and Catalyst OS software images support a specific software release, feature set, or platform. To access Cisco Feature Navigator, go to http://www.cisco.com/go/cfn. An account on Cisco.com is not required. |
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Note Table 2 lists only the Cisco IOS software release that introduced support for a given feature in a given Cisco IOS software release train. Unless noted otherwise, subsequent releases of that Cisco IOS software release train also support that feature. |
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Table 2 Feature Information for QoS Bandwidth Estimation |
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Feature Name |
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Releases |
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Feature Information |
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QoS Bandwidth Estimation |
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12.3(14)T |
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The QoS Bandwidth Estimation feature uses Corvil Bandwidth technology to allow you, as a network manager, to determine the bandwidth requirements to achieve user-specified quality of service (QoS) targets for networked applications. |
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The following sections provide information about this feature: |
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•Information About QoS Bandwidth Estimation |
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•How to Configure QoS Bandwidth Estimation |
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The following commands were introduced or modified by this feature: estimate bandwidth, show policy-map interface. |
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Glossary |
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Corvil Bandwidth—The optimum bandwidth that delivers predictability in QoS targets while maximizing the efficiency of the network. |
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CTD—Corvil traffic descriptor. A compact encoding of the distribution of bit and packet rates in a traffic aggregate over any given time window. CTDs summarize observed traffic and are input for the Corvil algorithm that calculates the minimum bandwidth required to deliver the user-specified QoS target for the observed traffic. |
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delay—The time taken from point to point in a network. Delay can be measured in either one-way or round-trip delay. See also latency. |
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latency—The delay on a router between the time a device receives a packet and the time that packet is forwarded out the destination port. |
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packet—A logical grouping of information that includes a header containing control information and (usually) user data. Packets most often refer to network-layer units of data. |
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policy map—Any defined rule that determines the use of resources within the network. A QoS policy map identifies the traffic class to which it applies and the instructions for one or more actions to take on that traffic. |
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QoS—quality of service. A measure of performance for a transmission system that reflects its transmission quality and service availability. Quality of service focuses on achieving appropriate network performance for networked applications; it is superior to best-effort performance. |
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traffic class—Three elements used to classify traffic. They include: a name, a series of match commands, and, if more than one match command exists in the traffic class, an instruction on how to evaluate the match commands. |
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==Xem thêm== |
==Xem thêm== |
Phiên bản lúc 18:25, ngày 20 tháng 8 năm 2008
MIME, viết tắt của Multipurpose Internet Mail Extensions là một chuẩn Internet về định dạng cho thư điện tử. Hầu như mọi thư điện tử Internet được truyền qua giao thức SMTP theo định dạng MIME. Vì gắn liền với chuẩn SMTP và MIME nên đôi khi thư điện tử Internet còn được gọi là thư điện tử SMTP/MIME.
Giới thiệu chung
lin`
Mô tả đầu gói tin MIME
MIME-Version
Content-Type
text html
Content-Transfer-Encoding
Encoded-Word
Table Of Contents
QoS Bandwidth Estimation
Contents
Prerequisites for QoS Bandwidth Estimation
Restrictions for QoS Bandwidth Estimation
Information About QoS Bandwidth Estimation
Feature Overview of QoS Bandwidth Estimation
Applying Corvil Bandwidth
Benefits of QoS Bandwidth Estimation
How to Configure QoS Bandwidth Estimation
Generating a Bandwidth Estimate
Attaching the Policy Map to an Interface
Restrictions
Verifying the Configuration
Configuration Examples for QoS Bandwidth Estimation
Generating Bandwidth Estimates for QoS Targets: Example
Attaching the Policy Map to an Interface: Example
Verifying the Configuration: Example
Additional References
Related Documents
Standards
MIBs
RFCs
Technical Assistance
Feature Information for QoS Bandwidth Estimation
Glossary
QoS Bandwidth Estimation First Published: March 29, 2005 Last Updated: April 30, 2007
The QoS Bandwidth Estimation feature uses Corvil Bandwidth technology to allow you, as a network manager, to determine the bandwidth requirements to achieve user-specified quality of service (QoS) targets for networked applications.
Finding Feature Information in This Module
Your Cisco IOS software release may not support all of the features documented in this module. For the latest feature information and caveats, see the release notes for your platform and software release. 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 "Feature Information for QoS Bandwidth Estimation" section.
Finding Support Information for Platforms and Cisco IOS and Catalyst OS Software Images
Use Cisco Feature Navigator to find information about platform support and Cisco IOS and Catalyst OS software image support. To access Cisco Feature Navigator, go to http://www.cisco.com/go/cfn. An account on Cisco.com is not required. Contents
•Prerequisites for QoS Bandwidth Estimation
•Restrictions for QoS Bandwidth Estimation
•Information About QoS Bandwidth Estimation
•How to Configure QoS Bandwidth Estimation
•Configuration Examples for QoS Bandwidth Estimation
•Additional References
•Feature Information for QoS Bandwidth Estimation
•Glossary Prerequisites for QoS Bandwidth Estimation
•Before using this feature, configure a class map and a policy map using the Modular Quality of Service (QoS) Command-Line Interface (CLI) (MQC), and specify the appropriate match criteria.
•This feature requires the purchase of a Cisco IOS software feature license. The right to use this feature is not included in the base Cisco IOS software license for the software image. Restrictions for QoS Bandwidth Estimation
This feature supports policy maps that are attached to interfaces in an output direction only. Information About QoS Bandwidth Estimation
To use the QoS Bandwidth Estimation feature, you should understand the following concepts:
•Feature Overview of QoS Bandwidth Estimation
•Benefits of QoS Bandwidth Estimation Feature Overview of QoS Bandwidth Estimation
Allocating adequate bandwidth is key to ensuring the network performance required for applications. However, allocating too much bandwidth can be costly. The QoS Bandwidth Estimation feature in Cisco IOS software uses Corvil Bandwidth technology to allow you, as a network manager, to determine the bandwidth requirements to achieve user-specified quality of service (QoS) targets for networked applications.
Corvil Bandwidth can determine the minimum bandwidth required to deliver traffic within customer-specified QoS targets with statistical reliability. From a network management perspective, an application's QoS requirements are characterized with respect to its sensitivity to delay and packet loss. Corvil Bandwidth provides a way to specify limits for delay and packet loss, and get a tight estimate of the minimum bandwidth essential to achieve desired application performance.
Corvil Bandwidth achieves its results by taking very short timescale (8-millisecond) snapshots of traffic and summarizing them in traffic descriptors that place very low overhead on the router because each descriptor has fewer than 300 bytes. These traffic descriptors record the exceptional events (bursts) and are input to the Corvil Bandwidth algorithm to calculate the minimum bandwidth required to deliver the user-specified QoS target for the observed traffic. (The QoS target is specified in terms of sensitivity to traffic delay and packet loss. For example, voice over IP [VoIP] traffic is very sensitive to both, whereas e-mail file transfer is sensitive to neither.)
As a result, turning on Corvil Bandwidth in the router allows you to obtain bandwidth values that can be used directly to configure the existing Cisco IOS QoS mechanisms on the router to achieve the required application performance as efficiently as possible.
For example, in Figure 1, Corvil Bandwidth is enabled on the router so that the serial interface can deliver the WAN traffic within the customer-specified QoS targets with statistical reliability.
Figure 1 Sample Topology Using QoS Bandwidth Estimation
Applying Corvil Bandwidth
The following sections describe how Corvil Bandwidth can be implemented:
•Link Sizing
•Bandwidth Allocations by Traffic Class Link Sizing
To use Corvil Bandwidth to establish the overall bandwidth requirement for a link, you start with QoS targets appropriate for the speed of the link and for the applications being carried on the link (Figure 2). The QoS targets are achieved as long as the link capacity is greater than or equal to the computed Corvil Bandwidth value.
Figure 2 Link Sizing
Bandwidth Allocations by Traffic Class
Corvil Bandwidth can be used to size bandwidth allocations for individual traffic classes defined via the MQC (Figure 3). You specify the QoS target for a traffic class, and Corvil Bandwidth reports the minimum amount of bandwidth that must be allocated to meet that target. The Corvil Bandwidth value can be used directly in the corresponding MQC policy. (The bandwidth allocation is not changed automatically.)
Figure 3 Bandwidth Allocations
Benefits of QoS Bandwidth Estimation
Table 1 shows the features and benefits of QoS Bandwidth Estimation using Corvil Bandwidth technology.
Table 1 QoS Bandwidth Estimation Feature
Benefits
User-specified packet loss and delay targets
•Establishment of service-level objectives for the desired performance of networked applications
•Elimination of operational overhead and guesswork in bandwidth provisioning and QoS configuration
•Potentially significant bandwidth cost savings while meeting QoS requirements
•Increased capability and flexibility to offer bandwidth-on-demand types of services
Frequent fine-grain traffic measurements
•More accurate calculation of bandwidth requirements
•Greater ability to meet more stringent QoS targets
Support for multiple traffic classes on an interface
•Individually specified QoS targets for each traffic class (class map) to calculate Corvil Bandwidth values
Corvil Bandwidth integrated with MQC
•Results available by traffic class
•Bandwidth adjustment enabled in the corresponding MQC-based policy
Corvil Bandwidth results reported in kbps
•Results directly applied via Cisco IOS MQC bandwidth command and to link-rate sizing
Corvil Bandwidth results available in class-based QoS MIB
•Integrated with Simple Network Management Protocol (SNMP)-based performance management tools
Low resource consumption on router
•Efficient to use, adding little additional processing or memory requirements
Available on any router interface
•Applicable to serial, T1/E1, Fast Ethernet, and other interfaces, as well as ATM virtual circuits (VCs), Frame Relay permanent virtual circuits (PVCs), multilink bundle interfaces, and virtual LAN (VLAN) subinterfaces
How to Configure QoS Bandwidth Estimation
This section contains the following procedures:
•Generating a Bandwidth Estimate (required)
•Attaching the Policy Map to an Interface (required)
•Verifying the Configuration (optional) Generating a Bandwidth Estimate
To generate a bandwidth estimate, perform the following task. SUMMARY STEPS
1. enable
2. configure terminal
3. policy-map policy-map-name
4. class [class-name | class-default]
5. bandwidth [bandwidth-kbps | remaining percent percentage | percent percentage]
6. estimate bandwidth [drop-one-in n] [delay-one-in n milliseconds n]
7. end 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
policy-map policy-map-name
Example:
Router(config)# policy-map my-policy
Specifies the name of the policy map to be created. Enters policy-map configuration mode.
•Enter the policy-map name.
Step 4
class [class-name | class-default]
Example:
Router(config-pmap)# class my-class
Specifies the class so that you can configure or modify its policy. Enters policy-map class configuration mode.
•Enter the class name or use the class-default keyword.
Step 5
bandwidth [bandwidth-kbps | remaining percent percentage | percent percentage]
Example:
Router(config-pmap-c)# bandwidth percent 20
Specifies or modifies the bandwidth allocated for a class belonging to a policy map.
•Enter the bandwidth to be set or modified.
Step 6
estimate bandwidth [drop-one-in n] [delay-one-in n milliseconds n]
Example:
Router(config-pmap-c)# estimate bandwidth drop-one-in 100 delay-one-in 100 milliseconds 50
(Optional) Estimates the bandwidth needed per traffic class for given quality of service (QoS) targets based on traffic data.
•Enter values for the packet loss target, the delay target, and the delay threshold.
Step 7
end
Example:
Router(config-pmap-c)# end
(Optional) Exits policy-map class configuration mode.
Attaching the Policy Map to an Interface
To attach the policy map to an interface, perform the following task. Restrictions
This feature supports policy maps attached to an interface in the output direction only. SUMMARY STEPS
1. enable
2. configure terminal
3. interface type number [name-tag]
4. service-policy {input | output} policy-map-name
5. end 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
interface type number [name-tag]
Example:
Router(config)# interface fastethernet0/1
Configures the specified interface and enters interface configuration mode.
•Enter interface type and number.
Step 4
service-policy {input | output} policy-map-name
Example:
Router(config-if)# service-policy output my-policy
Specifies the name of the policy map to be attached to the interface.
Note You can configure policy maps on ingress or egress routers and attach them in the input or output direction of an interface. The direction (input or output) and the router (ingress or egress) to which the policy map should be attached vary according to your network configuration. For this feature, only the output direction is supported.
•Enter the output keyword followed by the policy map name.
Step 5
end
Example:
Router(config-if)# end
(Optional) Exits interface configuration mode.
Verifying the Configuration
To verify that bandwidth estimates have been generated, perform the following task. SUMMARY STEPS
1. enable
2. show policy-map interface interface-name [vc [vpi/] vci] [dlci dlci] [input | output]
3. exit DETAILED STEPS
Command or Action
Purpose
Step 1
enable
Example:
Router> enable
Enables privileged EXEC mode.
•Enter your password if prompted.
Step 2
show policy-map interface interface-name [vc [vpi/]vci][dlci dlci][input | output]
Example:
Router# show policy-map interface fastethernet0/1
Displays the packet statistics of all classes that are configured for all service policies either on the specified interface or subinterface or on a specific PVC on the interface.
•Enter the interface name.
Step 3
exit
Example:
Router# exit
(Optional) Exits privileged EXEC mode.
Configuration Examples for QoS Bandwidth Estimation
This section contains the following configuration examples:
•Generating Bandwidth Estimates for QoS Targets: Example
•Attaching the Policy Map to an Interface: Example
•Verifying the Configuration: Example Generating Bandwidth Estimates for QoS Targets: Example
In the following example, a policy map and a traffic class are configured. Then bandwidth estimates for QoS targets including packet loss rate, delay time and probability, and timeframe in milliseconds are configured.
Router# configure terminal
Router(config)# policy-map my-policy
Router(config-pmap)# class my-class
Router(config-pmap-c)# bandwidth percent 20
Router(config-pmap-c)# estimate bandwidth drop-one-in 100 delay-one-in 100 milliseconds 50
Router(config-pmap-c)# end
Attaching the Policy Map to an Interface: Example
The following example shows the policy map named my-policy being attached to Fast Ethernet interface 0/1 in the output direction:
Router# configure terminal
Router(config)# interface f0/1
Router(config-if)# service-policy output my-policy
Router(config-if)# exit
Verifying the Configuration: Example
The following example from the show policy-map interface command verifies that the policy map named my-policy is attached to Fast Ethernet interface 0/1 in the output direction and that bandwidth estimates have been created:
Router# show policy-map interface fastethernet0/1
FastEthernet0/1
Service-policy output: my-policy
Class-map: icmp (match-all)
199 packets, 22686 bytes
30 second offered rate 0 bps, drop rate 0 bps
Match: access-group 101
Bandwidth Estimation:
Quality-of-Service targets:
drop no more than one packet in 1000 (Packet loss < 0.10%)
delay no more than one packet in 100 by 40 (or more) milliseconds
(Confidence: 99.0000%)
Corvil Bandwidth: 1 kbits/sec
Class-map: class-default (match-any)
112 packets, 14227 bytes
30 second offered rate 0 bps, drop rate 0 bps
Match: any
Bandwidth Estimation:
Quality-of-Service targets:
<none specified, falling back to drop no more than one packet in 500
Corvil Bandwidth: 1 kbits/sec
Additional References
The following sections provide references related to the QoS Bandwidth Estimation feature. Related Documents Related Topic
Document Title
QoS commands: complete command syntax, command modes, command history, defaults, usage guidelines, and examples
Cisco IOS Quality of Service Solutions Command Reference
Information about attaching policy maps to interfaces using the MQC
"Applying QoS Features Using the MQC" module
Standards Standard
Title
No new or modified standards are supported, and support for existing standards has not been modified.
—
MIBs MIB
MIBs Link
•CISCO-CLASS-BASED-QOS-MIB
•CISCO-CLASS-BASED-QOS-CAPABILITY-MIB
To locate and download MIBs for selected platforms, Cisco IOS releases, and feature sets, use Cisco MIB Locator found at the following URL:
RFCs RFC
Title
No new or modified RFCs are supported, and support for existing RFCs has not been modified.
—
Technical Assistance Description
Link
The Cisco Support website provides extensive online resources, including documentation and tools for troubleshooting and resolving technical issues with Cisco products and technologies.
To receive security and technical information about your products, you can subscribe to various services, such as the Product Alert Tool (accessed from Field Notices), the Cisco Technical Services Newsletter, and Really Simple Syndication (RSS) Feeds.
Access to most tools on the Cisco Support website requires a Cisco.com user ID and password.
http://www.cisco.com/techsupport
Feature Information for QoS Bandwidth Estimation
Table 2 lists the release history for this feature.
Not all commands may be available in your Cisco IOS software release. For release information about a specific command, see the command reference documentation.
Use Cisco Feature Navigator to find information about platform support and software image support. Cisco Feature Navigator enables you to determine which Cisco IOS and Catalyst OS software images support a specific software release, feature set, or platform. To access Cisco Feature Navigator, go to http://www.cisco.com/go/cfn. An account on Cisco.com is not required.
Note Table 2 lists only the Cisco IOS software release that introduced support for a given feature in a given Cisco IOS software release train. Unless noted otherwise, subsequent releases of that Cisco IOS software release train also support that feature.
Table 2 Feature Information for QoS Bandwidth Estimation Feature Name
Releases
Feature Information
QoS Bandwidth Estimation
12.3(14)T
The QoS Bandwidth Estimation feature uses Corvil Bandwidth technology to allow you, as a network manager, to determine the bandwidth requirements to achieve user-specified quality of service (QoS) targets for networked applications.
The following sections provide information about this feature:
•Information About QoS Bandwidth Estimation
•How to Configure QoS Bandwidth Estimation
The following commands were introduced or modified by this feature: estimate bandwidth, show policy-map interface.
Glossary
Corvil Bandwidth—The optimum bandwidth that delivers predictability in QoS targets while maximizing the efficiency of the network.
CTD—Corvil traffic descriptor. A compact encoding of the distribution of bit and packet rates in a traffic aggregate over any given time window. CTDs summarize observed traffic and are input for the Corvil algorithm that calculates the minimum bandwidth required to deliver the user-specified QoS target for the observed traffic.
delay—The time taken from point to point in a network. Delay can be measured in either one-way or round-trip delay. See also latency.
latency—The delay on a router between the time a device receives a packet and the time that packet is forwarded out the destination port.
packet—A logical grouping of information that includes a header containing control information and (usually) user data. Packets most often refer to network-layer units of data.
policy map—Any defined rule that determines the use of resources within the network. A QoS policy map identifies the traffic class to which it applies and the instructions for one or more actions to take on that traffic.
QoS—quality of service. A measure of performance for a transmission system that reflects its transmission quality and service availability. Quality of service focuses on achieving appropriate network performance for networked applications; it is superior to best-effort performance.
traffic class—Three elements used to classify traffic. They include: a name, a series of match commands, and, if more than one match command exists in the traffic class, an instruction on how to evaluate the match commands.