- Preface
- Read Me First
- Software Packaging and Architecture
- Using Cisco IOS XE Software
- Console Port, Telnet, and SSH Handling
- Consolidated Packages and Sub-Package Management
- Software Upgrade Process
- High Availability Overview
- Broadband Scalability and Performance
- UniDirectional Link Detection (UDLD) Protocol
- Using the Management Ethernet Interface
- Multilink PPP Support for the ASR 1000 Series Aggregation Services Routers
- Synchronous Ethernet Support
- IEEE 1588v2 PTP Support
- Configuring Bridge Domain Interfaces
- Enabling Support for Tunable DWDM-XFP-C
- Monitoring and Maintaining Multilink Frame Relay
- Configuring MPLS Layer 2 VPNs
- Configuring Support for Management Using the REST API
- LSM-MLDP-based MVPN Support
- Tracing and Trace Management
- Packet Trace
- Configuring and Accessing the Web User Interface
- PPP Half-Bridge on the Cisco ASR 1000 Series Routers
- Unsupported Commands
- Configuration Examples
- Finding Feature Information
- Contents
- Information About Packet Trace
- Usage Guidelines for Configuring Packet Trace
- Configuring Packet Trace
- Displaying Packet-Trace Information
- Removing Packet-Trace Data
- Configuration Examples for Packet Trace
- Additional References
- Feature Information for Packet Trace
Packet Trace
First Published: August 03, 2016
The Packet-Trace feature provides a detailed understanding of how data packets are processed by the Cisco IOS XE platform, and thus helps customers to diagnose issues and troubleshoot them more efficiently. This module provides information about how to use the Packet-Trace feature.
Finding Feature Information
Your software release might not support all the features documented in this module. For the latest feature information and caveats, see the release notes for your platform and software release. To find information about the features documented in this module, and to see a list of the releases in which each feature is supported, see the “Feature Information for Packet Trace” section.
Use Cisco Feature Navigator to find information about platform support and Cisco 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
Information About Packet Trace
The Packet-Trace feature provides three levels of inspection for packets: accounting, summary, and path data. Each level provides a detailed view of packet processing at the cost of some packet processing capability. However, Packet Trace limits inspection to packets that match the debug platform condition statements, and is a viable option even under heavy-traffic situations in customer environments.
Table 21-1 explains the three levels of inspection provided by packet trace.
Usage Guidelines for Configuring Packet Trace
Consider the following best practices while configuring the Packet-Trace feature:
- Use of ingress conditions when using the Packet-Trace feature is recommended for a more comprehensive view of packets.
- Packet-trace configuration requires data-plane memory. On systems where data-plane memory is constrained, carefully consider how you will select the packet-trace values. A close approximation of the amount of memory consumed by packet trace is provided by the following equation:
memory required = (statistics overhead) + number of packets * (summary size + data size + packet copy size).
When the Packet-Trace feature is enabled, a small, fixed amount of memory is allocated for statistics. Similarly, when per-packet data is captured, a small, fixed amount of memory is required for each packet for summary data. However, as shown by the equation, you can significantly influence the amount of memory consumed by the number of packets you select to trace, and whether you collect path data and copies of packets.
Configuring Packet Trace
Perform the following steps to configure the Packet-Trace feature.
Note
The amount of memory consumed by the Packet-Trace feature is affected by the packet-trace configuration. You should carefully select the size of per-packet path data and copy buffers and the number of packets to be traced in order to avoid interrupting normal services. You can check the current data-plane DRAM memory consumption by using the show platform hardware qfp active infrastructure exmem statistics command. See the “Configuration Examples for Packet Trace” section for more information about configuring packet trace.
SUMMARY STEPS
2. debug platform packet-trace packet pkt-num [fia-trace | summary-only] [data-size data-size ] [circular]
3. debug platform packet-trace punt
4. debug platform condition [ipv4 | ipv6] [interface interface ] [access-list access-list -name | ipv4-address / subnet-mask | ipv6-address / subnet-mask ] [ingress | egress]
5. debug platform condition start
6. debug platform condition stop
7. show platform packet-trace {configuration | statistics | summary | packet {all | pkt-num }}
DETAILED STEPS
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Enables the privileged EXEC mode. Enter your password if prompted. |
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debug platform packet-trace packet pkt-num [fia-trace | summary-only] [circular] [data-size data-size ] Router# debug platform packet-trace packets 2048 summary-only |
Collects summary data for a specified number of packets. Captures feature path data by the default, and optionally performs FIA trace. pkt-num —Specifies the maximum number of packets maintained at a given time. fia-trace —Provides detailed level of data capture, including summary data, feature-specific data. Also displays each feature entry visited during packet processing. summary-only —Enables the capture of summary data with minimal details. circular —Saves the data of the most recently traced packets. data-size —Specifies the size of data buffers for storing feature and FIA trace data for each packet in bytes. When very heavy packet processing is performed on packets, users can increase the size of the data buffers if necessary. The default value is 2048. |
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debug platform packet-trace punt |
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debug platform condition [ipv4 | ipv6] [interface interface ][access-list access-list -name | ipv4-address / subnet-mask | ipv6-address / subnet-mask ] [ingress| egress] |
Specifies the matching criteria for tracing packets. Provides the ability to filter by protocol, IP address and subnet mask, access control list (ACL), interface, and direction. |
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debug platform condition start |
Enables the specified matching criteria and starts packet tracing. |
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show platform packet-trace {configuration | statistics | summary | packet {all | pkt-num }} |
Displays packet-trace data according to the specified option. See Table 21-1 for detailed information about the show command options. |
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Removes the configurations provided by the debug platform condition and debug platform packet-trace commands. |
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Displaying Packet-Trace Information
Use these show commands to display packet-trace information.
Removing Packet-Trace Data
Use these commands to clear packet-trace data.
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Configuration Examples for Packet Trace
This section provides the following configuration examples:
Example: Configuring Packet Trace
This example describes how to configure packet trace and display the results. In this example, incoming packets to Gigabit Ethernet interface 0/0/2 are traced, and FIA-trace data is captured for the first 128 packets. Also, the input packets are copied. The show platform packet-trace packet 10 command displays the summary data and each feature entry visited during packet processing for packet 10.
Router> enable
Example: Using Packet Trace
This example provides a scenario in which packet trace is used to troubleshoot packet drops for a NAT configuration on a Cisco ASR 1006 Router. This example shows how you can effectively utilize the level of detail provided by the Packet-Trace feature to gather information about an issue, isolate the issue, and then find a solution.
In this scenario, you can detect that there are issues, but are not sure where to start troubleshooting. You should, therefore, consider accessing the Packet-Trace summary for a number of incoming packets.
The output shows that packets are dropped due to NAT configuration on Gigabit Ethernet interface 0/0/0, which enables you to understand that an issue is occurring on a specific interface. Using this information, you can limit which packets to trace, reduce the number of packets for data capture, and increase the level of inspection.
Additional References
Related Documents
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Standards
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MIBs
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To locate and download MIBs for selected platforms, Cisco IOS releases, and feature sets, use Cisco MIB Locator found at this URL: |
RFCs
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Technical Assistance
Feature Information for Packet Trace
Table 21-4 lists the features in this module and provides links to specific configuration information.
Use Cisco Feature Navigator to find information about platform support and software image support. Cisco Feature Navigator enables you to determine which 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 21-4 lists only the software releases that support a given feature in a given software release train. Unless noted otherwise, subsequent releases of that software release train also support that feature.
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