Tracing is a function that logs internal events. Trace files containing trace messages are automatically created and saved to the tracelogs directory on the hard disk: file system on the router, which stores tracing files in bootflash.

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

• Troubleshooting—Helps to locate and solve an issue with a router. The trace files can be accessed in diagnostic mode even if other system issues are occurring simultaneously.

• Debugging—Helps to obtain a detailed view of system actions and operations.

Tracing logs the contents of internal events on a router. Trace files containing all the trace output pertaining to a module are periodically created and updated and 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 files can be copied to other destinations using file transfer functions (such as FTP and TFTP) and opened using a plain text editor.

Note	Tracing cannot be disabled on a router.

Use the following commands to view trace information and set tracing levels:

• show logging process module—Shows the most recent trace information for a specific module. This command can be used in privileged EXEC and diagnostic modes. When used in diagnostic mode, this command can gather trace log information during a Cisco IOS XE failure.

• set platform software trace—Sets a tracing level that determines the types of messages that are stored in the output. For more information on tracing levels, see Tracing Levels.

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

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

If a tracing level is set, messages are collected from both lower tracing levels and from its own level.

For example, setting the tracing level to 3 (error) means that the trace file will contain output messages for levels: 0 (emergencies), 1 (alerts), 2 (critical), and 3 (error).

If you set the trace level to 4 (warning), it results in output messages for levels: 0 (emergencies), 1 (alerts), 2 (critical), 3 (error), and 4 (warning).

The default tracing level for every module on the router is 5 (notice).

A tracing level is not set in a configuration mode, which results in tracing-level settings being returned to default values after the router reloads.

Caution

Setting the tracing level of a module to debug level or higher can have a negative impact on the performance.

Caution

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

By default, all the modules on a router are set to 5 (notice). This setting is maintained unless changed by a user.

To see the tracing level for a module on a router, enter the show logging process command in privileged EXEC mode or diagnostic mode.

The following example shows how the show logging process command is used to view the tracing levels of the forwarding manager processes on an active RP:

Router# showlogging process forwarding-manager rp active
Module Name                     Trace Level      
-----------------------------------------------
acl                             Notice           
binos                           Notice           
binos/brand                     Notice           
bipc                            Notice           
bsignal                         Notice           
btrace                          Notice           
cce                             Notice           
cdllib                          Notice           
cef                             Notice           
chasfs                          Notice           
chasutil                        Notice           
erspan                          Notice           
ess                             Notice           
ether-channel                   Notice           
evlib                           Notice           
evutil                          Notice           
file_alloc                      Notice           
fman_rp                         Notice           
fpm                             Notice           
fw                              Notice           
icmp                            Notice           
interfaces                      Notice           
iosd                            Notice           
ipc                             Notice           
ipclog                          Notice           
iphc                            Notice           
IPsec                           Notice           
mgmte-acl                       Notice           
mlp                             Notice           
mqipc                           Notice           
nat                             Notice           
nbar                            Notice           
netflow                         Notice           
om                              Notice           
peer                            Notice           
qos                             Notice           
route-map                       Notice           
sbc                             Notice           
services                        Notice           
sw_wdog                         Notice           
tdl_acl_config_type             Notice           
tdl_acl_db_type                 Notice           
tdl_cdlcore_message             Notice           
tdl_cef_config_common_type      Notice           
tdl_cef_config_type             Notice           
tdl_dpidb_config_type           Notice           
tdl_fman_rp_comm_type           Notice           
tdl_fman_rp_message             Notice           
tdl_fw_config_type              Notice           
tdl_hapi_tdl_type               Notice           
tdl_icmp_type                   Notice           
tdl_ip_options_type             Notice           
tdl_ipc_ack_type                Notice           
tdl_IPsec_db_type               Notice           
tdl_mcp_comm_type               Notice           
tdl_mlp_config_type             Notice           
tdl_mlp_db_type                 Notice           
tdl_om_type                     Notice           
tdl_ui_message                  Notice           
tdl_ui_type                     Notice           
tdl_urpf_config_type            Notice           
tdllib                          Notice           
trans_avl                       Notice           
uihandler                       Notice           
uipeer                          Notice           
uistatus                        Notice           
urpf                            Notice           
vista                           Notice           
wccp                            Notice           

To set a tracing level for a module on a router, or for all the modules within a process on a router, enter the set platform software trace command in the privileged EXEC mode or diagnostic mode.

The following example shows the tracing level for the ACL module in the Forwarding Manager of the ESP processor in slot 0 set to info:

set platform software trace forwarding-manager F0 acl info

To view the trace messages in the trace buffer or file, enter the show logging process command in privileged EXEC or diagnostic mode. In the following example, the trace messages for the Host Manager process in Route Processor slot 0 are viewed using the show logging process command:

Router# show logging process host-manager R0
08/23 12:09:14.408 [uipeer]: (info): Looking for a ui_req msg
08/23 12:09:14.408 [uipeer]: (info): Start of request handling for con 0x100a61c8
08/23 12:09:14.399 [uipeer]: (info): Accepted connection for 14 as 0x100a61c8
08/23 12:09:14.399 [uipeer]: (info): Received new connection 0x100a61c8 on descriptor 14
08/23 12:09:14.398 [uipeer]: (info): Accepting command connection on listen fd 7
08/23 11:53:57.440 [uipeer]: (info): Going to send a status update to the shell manager in slot 0
08/23 11:53:47.417 [uipeer]: (info): Going to send a status update to the shell manager in slot 0