Cisco ASR 1000 Series Aggregation Services Routers Software Configuration Guide

Tracing Overview

Tracing is a function that logs internal events. Trace files are automatically created and saved to the tracelogs directory on the harddisk: file system on all Cisco ASR 1000 Series Routers except the Cisco ASR 1002 Router, which stores tracing files in bootflash:. Trace files are used to store tracing data.

The contents of trace files are useful for the following purposes:

• Troubleshooting—If a Cisco ASR 1000 Series Router is having an issue, the trace file output may provide information that is useful for locating and solving the problem. Trace files can almost always be accessed through diagnostic mode even if other system issues are occurring.
• Debugging—The trace file outputs can help users get a more detailed view of system actions and operations.

How Tracing Works

The tracing function logs the contents of internal events on the Cisco ASR 1000 Series Routers. Trace files with all trace output for a module are periodically created and updated and are stored in the tracelog directory. Trace files can be erased from this directory to recover space on the file system without impacting system performance.

The most recent trace information for a specific module can be viewed using the show platform software trace message privileged EXEC and diagnostic mode command. This command can be entered to gather trace log information even during an IOS failure because it is available in diagnostic mode.

Trace files can be copied to other destinations using most file transfer functions (such as FTP, TFTP, and so on) and opened using a plaintext editor.

Tracing cannot be disabled on the Cisco ASR 1000 Series Router. Trace levels, however, which set the message types that generate trace output, are user-configurable and can be set using the platform trace commands. If a user wants to modify the trace level to increase or decrease the amount of trace message output, the user should set a new tracing level using the platform trace commands. Trace levels can be set by process using the all-modules keyword within the platform trace commands, or by module within a process. See the platform trace command reference for more information on this command, and the “Tracing Levels” section of this document for additional information on tracing levels.

Tracing Levels

Tracing levels determine how much information about a module should be stored in the trace buffer or file.

shows all of the trace levels that are available and provides descriptions of what types of messages are displayed with each tracing level.

Trace level settings are leveled, meaning that every setting will contain all messages from the lower setting plus the messages from its own setting. For instance, setting the trace level to 3(error) ensures that the trace file will contain all output for the 0 (emergencies), 1 (alerts), 2 (critical), and 3 (error) settings. Setting the trace level to 4 (warning) will ensure that all trace output for the specific module will be included in that trace file.

The default tracing level for every module on the Cisco ASR 1000 Series Router is notice.

All trace levels are not user-configurable. Specifically, the alert, critical, and notice tracing levels cannot be set by users. If you wish to trace these messages, set the trace level to a higher level that will collect these messages.

When setting trace levels, it is also important to remember that the setting is not done in a configuration mode, so trace level settings are returned to their defaults after every router reload.

Caution Setting tracing of a module to the debug level or higher can have a negative performance impact. Setting tracing to this level or higher should be done with discretion.

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Caution Setting a large number of modules to high tracing levels can severely degrade performance. If a high level of tracing is needed in a specific context, it is almost always preferable to set a single module on a higher tracing level rather than setting multiple modules to high tracing levels.

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Viewing a Tracing Level

By default, all modules on the Cisco ASR 1000 Series Routers are set to notice. This setting will be maintained unless changed by a user.

To see the tracing level for any module on the Cisco ASR 1000 Series Routers, enter the show platform software trace level command in privileged EXEC or diagnostic mode.

In the following example, the show platform software trace level command is used to view the tracing levels of the Forwarding Manager processes on the active RP:

Setting a Tracing Level

To set a tracing level for any module on the Cisco ASR 1000 Series Routers, or for all modules within a process on the Cisco ASR 1000 Series Router, enter the platform software trace privileged EXEC and diagnostic mode command.

In the following example, the trace level for the forwarding processor module in the Forwarding Manager of the ESP processor in slot 0 is set to the informational tracing level (info):

In the following example, the trace level for the forwarding processor module in the Forwarding Manager of the ESP processor in slot R0 is set to the informational tracing level (max):

See the platform trace boottime process forwarding-manager moduleinterfaces and platform trace runtime process forwarding-manager moduleinterfaces command reference for additional information about the options for this command.

Viewing the Content of the Trace Buffer

To view the trace messages in the trace buffer or file, enter the show platform software trace message privileged EXEC and diagnostic mode command.

In the following example, the trace messages for the Host Manager process in Route Processor slot 0 are viewed using the show platform software trace message command: