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Table Of Contents
Configuring System Message Logging
Understanding System Message Logging
Configuring System Message Logging
Default System Message Logging Configuration
Setting the Message Display Destination Device
Enabling and Disabling Time Stamps on Log Messages
Enabling and Disabling Sequence Numbers in Log Messages
Defining the Message Severity Level
Limiting Syslog Messages Sent to the History Table and to SNMP
Enabling the Configuration-Change Logger
Configuring UNIX Syslog Servers
Logging Messages to a UNIX Syslog Daemon
Configuring the UNIX System Logging Facility
Displaying the Logging Configuration
Configuring System Message Logging
This chapter describes how to configure system message logging on the Cisco ME 3800X and ME 3600X switch.
Note
For complete syntax and usage information for the commands used in this chapter, see the Cisco IOS Configuration Fundamentals Command Reference, Release 15.x.
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Caution
Understanding System Message Logging
By default, a switch sends the output from system messages and debug privileged EXEC commands to a logging process. The logging process controls the distribution of logging messages to various destinations, such as the logging buffer, terminal lines, or a UNIX syslog server, depending on your configuration. The process also sends messages to the console.
Note
When the logging process is disabled, messages are sent only to the console. The messages are sent as they are generated, so message and debug output are interspersed with prompts or output from other commands. Messages appear on the console after the process that generated them has finished.
You can set the severity level of the messages to control the type of messages displayed on the consoles and each of the destinations. You can time-stamp log messages or set the syslog source address to enhance real-time debugging and management. For information on possible messages, see the system message guide for this release.
You can access logged system messages by using the switch command-line interface (CLI) or by saving them to a properly configured syslog server. The switch software saves syslog messages in an internal buffer.
You can remotely monitor system messages by viewing the logs on a syslog server or by accessing the switch through Telnet or through the console port.
Configuring System Message Logging
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System Log Message Format
System log messages can contain up to 80 characters and a percent sign (%), which follows the optional sequence number or time-stamp information, if configured. Messages appear in this format:
seq no:timestamp: %facility-severity-MNEMONIC:description
The part of the message preceding the percent sign depends on the setting of the service sequence-numbers, service timestamps log datetime, service timestamps log datetime [localtime] [msec] [show-timezone], or service timestamps log uptime global configuration command.
Table 28-1 describes the elements of syslog messages.
Table 28-1 System Log Message Elements
seq no:
Stamps log messages with a sequence number only if the service sequence-numbers global configuration command is configured.
For more information, see the "Enabling and Disabling Sequence Numbers in Log Messages" section.
timestamp formats:
mm/dd hh:mm:ss
or
hh:mm:ss (short uptime)
or
d h (long uptime)Date and time of the message or event. This information appears only if the service timestamps log [datetime | log] global configuration command is configured.
For more information, see the "Enabling and Disabling Time Stamps on Log Messages" section.
facility
The facility to which the message refers (for example, SNMP, SYS, and so forth). For a list of supported facilities, see Table 28-4.
severity
Single-digit code from 0 to 7 that is the severity of the message. For a description of the severity levels, see Table 28-3.
MNEMONIC
Text string that uniquely describes the message.
description
Text string containing detailed information about the event being reported.
This example shows a partial switch system message:
00:00:46: %LINK-3-UPDOWN: Interface Port-channel1, changed state to up00:00:47: %LINK-3-UPDOWN: Interface GigabitEthernet0/1, changed state to up00:00:47: %LINK-3-UPDOWN: Interface GigabitEthernet0/2, changed state to up00:00:48: %LINEPROTO-5-UPDOWN: Line protocol on Interface Vlan1, changed state to down00:00:48: %LINEPROTO-5-UPDOWN: Line protocol on Interface GigabitEthernet0/1, changed state to down 2*Mar 1 18:46:11: %SYS-5-CONFIG_I: Configured from console by vty2 (10.34.195.36)18:47:02: %SYS-5-CONFIG_I: Configured from console by vty2 (10.34.195.36)*Mar 1 18:48:50.483 UTC: %SYS-5-CONFIG_I: Configured from console by vty2 (10.34.195.36)Default System Message Logging Configuration
Table 28-2 shows the default system message logging configuration.
Table 28-2 Default System Message Logging Configuration
System message logging to the console
Enabled.
Console severity
Debugging (and numerically lower levels; see Table 28-3).
Logging file configuration
No filename specified.
Logging buffer size
4096 bytes.
Logging history size
1 message.
Time stamps
Disabled.
Synchronous logging
Disabled.
Logging server
Disabled.
Syslog server IP address
None configured.
Server facility
Local7 (see Table 28-4).
Server severity
Informational (and numerically lower levels; see Table 28-3).
Disabling Message Logging
Message logging is enabled by default. It must be enabled to send messages to any destination other than the console. When enabled, log messages are sent to a logging process, which logs messages to designated locations asynchronously to the processes that generated the messages.
Beginning in privileged EXEC mode, follow these steps to disable message logging. This procedure is optional.
Disabling the logging process can slow down the switch because a process must wait until the messages are written to the console before continuing. When the logging process is disabled, messages appear on the console as soon as they are produced, often appearing in the middle of command output.
The logging synchronous global configuration command also affects the display of messages to the console. When this command is enabled, messages appear only after you press Return. For more information, see the "Synchronizing Log Messages" section.
To re-enable message logging after it has been disabled, use the logging on global configuration command.
Setting the Message Display Destination Device
If message logging is enabled, you can send messages to specific locations in addition to the console. Beginning in privileged EXEC mode, use one or more of the following commands to specify the locations that receive messages. This procedure is optional.
Step 1
configure terminal
Enter global configuration mode.
Step 2
logging buffered [size]
Log messages to an internal buffer on the switch. The default buffer size is 4096. The range is 4096 to 2147483647 bytes.
If the switch fails, the log file is lost unless you previously saved it to Flash memory. See Step 4.
Note
Step 3
logging host
Log messages to a UNIX syslog server host.
For host, specify the name or IP address of the host to be used as the syslog server.
To build a list of syslog servers that receive logging messages, enter this command more than once.
For complete syslog server configuration steps, see the "Configuring UNIX Syslog Servers" section.
Step 4
logging file flash:filename [max-file-size [min-file-size]] [severity-level-number | type]
Store log messages in a file in flash memory.
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Step 5
end
Return to privileged EXEC mode.
Step 6
terminal monitor
Log messages to a nonconsole terminal during the current session.
Terminal parameter-setting commands are set locally and do not remain in effect after the session has ended. You must perform this step for each session to see the debugging messages.
Step 7
show running-config
Verify your entries.
Step 8
copy running-config startup-config
(Optional) Save your entries in the configuration file.
The logging buffered global configuration command copies logging messages to an internal buffer. The buffer is circular, so newer messages overwrite older messages after the buffer is full. To display the messages that are logged in the buffer, use the show logging privileged EXEC command. The first message displayed is the oldest message in the buffer. To clear the contents of the buffer, use the clear logging privileged EXEC command.
To disable logging to the console, use the no logging console global configuration command. To disable logging to a file, use the no logging file [severity-level-number | type] global configuration command.
Synchronizing Log Messages
You can synchronize unsolicited messages and debug privileged EXEC command output with solicited device output and prompts for a specific console port line or virtual terminal line. You can identify the types of messages to be output asynchronously based on the level of severity. You can also configure the maximum number of buffers for storing asynchronous messages for the terminal after which messages are dropped.
When synchronous logging of unsolicited messages and debug command output is enabled, unsolicited device output appears on the console or printed after solicited device output appears or is printed. Unsolicited messages and debug command output appears on the console after the prompt for user input is returned. Therefore, unsolicited messages and debug command output are not interspersed with solicited device output and prompts. After the unsolicited messages appear, the console again displays the user prompt.
Beginning in privileged EXEC mode, follow these steps to configure synchronous logging. This procedure is optional.
To disable synchronization of unsolicited messages and debug output, use the no logging synchronous [level severity-level | all] [limit number-of-buffers] line configuration command.
Enabling and Disabling Time Stamps on Log Messages
By default, log messages are not time-stamped.
Beginning in privileged EXEC mode, follow these steps to enable time-stamping of log messages. This procedure is optional.
To disable time stamps for both debug and log messages, use the no service timestamps global configuration command.
This example shows part of a logging display with the service timestamps log datetime global configuration command enabled:
*Mar 1 18:46:11: %SYS-5-CONFIG_I: Configured from console by vty2 (10.34.195.36)This example shows part of a logging display with the service timestamps log uptime global configuration command enabled:
00:00:46: %LINK-3-UPDOWN: Interface Port-channel1, changed state to upEnabling and Disabling Sequence Numbers in Log Messages
Because there is a chance that more than one log message can have the same time stamp, you can display messages with sequence numbers so that you can unambiguously see a single message. By default, sequence numbers in log messages are not displayed.
Beginning in privileged EXEC mode, follow these steps to enable sequence numbers in log messages. This procedure is optional.
To disable sequence numbers, use the no service sequence-numbers global configuration command.
This example shows part of a logging display with sequence numbers enabled:
000019: %SYS-5-CONFIG_I: Configured from console by vty2 (10.34.195.36)Defining the Message Severity Level
You can limit messages displayed to the selected device by specifying the severity level of the message, which are described in Table 28-3.
Beginning in privileged EXEC mode, follow these steps to define the message severity level. This procedure is optional.
Step 1
configure terminal
Enter global configuration mode.
Step 2
logging console level
Limit messages logged to the console.
By default, the console receives debugging messages and numerically lower levels (see Table 28-3).
Step 3
logging monitor level
Limit messages logged to the terminal lines.
By default, the terminal receives debugging messages and numerically lower levels (see Table 28-3).
Step 4
logging trap level
Limit messages logged to the syslog servers.
By default, syslog servers receive informational messages and numerically lower levels (see Table 28-3).
For complete syslog server configuration steps, see the "Configuring UNIX Syslog Servers" section.
Step 5
end
Return to privileged EXEC mode.
Step 6
show running-config
or
show loggingVerify your entries.
Step 7
copy running-config startup-config
(Optional) Save your entries in the configuration file.
Note
To disable logging to the console, use the no logging console global configuration command. To disable logging to a terminal other than the console, use the no logging monitor global configuration command. To disable logging to syslog servers, use the no logging trap global configuration command.
Table 28-3 describes the level keywords. It also lists the corresponding UNIX syslog definitions from the most severe level to the least severe level.
The software generates four other categories of messages:
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Limiting Syslog Messages Sent to the History Table and to SNMP
If you enabled syslog message traps to be sent to an SNMP network management station by using the snmp-server enable trap global configuration command, you can change the level of messages sent and stored in the switch history table. You also can change the number of messages that are stored in the history table.
Messages are stored in the history table because SNMP traps are not guaranteed to reach their destination. By default, one message of the level warning and numerically lower levels (see Table 28-3) are stored in the history table even if syslog traps are not enabled.
Beginning in privileged EXEC mode, follow these steps to change the level and history table size defaults. This procedure is optional.
Step 1
configure terminal
Enter global configuration mode.
Step 2
logging history level1
Change the default level of syslog messages stored in the history file and sent to the SNMP server.
See Table 28-3 for a list of level keywords.
By default, warnings, errors, critical, alerts, and emergencies messages are sent.
Step 3
logging history size number
Specify the number of syslog messages that can be stored in the history table.
The default is to store one message. The range is 0 to 500 messages.
Step 4
end
Return to privileged EXEC mode.
Step 5
show running-config
Verify your entries.
Step 6
copy running-config startup-config
(Optional) Save your entries in the configuration file.
1 Table 28-3 lists the level keywords and severity level. For SNMP usage, the severity level values increase by 1. For example, emergencies equal 1, not 0, and critical equals 3, not 2.
When the history table is full (it contains the maximum number of message entries specified with the logging history size global configuration command), the oldest message entry is deleted from the table to allow the new message entry to be stored.
To return the logging of syslog messages to the default level, use the no logging history global configuration command. To return the number of messages in the history table to the default value, use the no logging history size global configuration command.
Enabling the Configuration-Change Logger
You can enable a configuration logger to keep track of configuration changes made with the command-line interface (CLI). When you enter the logging enable configuration-change logger configuration command, the log records the session, the user, and the command that was entered to change the configuration. You can configure the size of the configuration log from 1 to 1000 entries (the default is 100). You can clear the log at any time by entering the no logging enable command followed by the logging enable command to disable and reenable logging.
Use the show archive log config {all | number [end-number] | user username [session number] number [end-number] | statistics} [provisioning] privileged EXEC command to display the complete configuration log or the log for specified parameters.
The default is that configuration logging is disabled.
For information about the commands, refer to the Cisco IOS Configuration Fundamentals and Network Management Command Reference, Release 15.x
Beginning in privileged EXEC mode, follow these steps to enable configuration logging:
This example shows how to enable the configuration-change logger and to set the number of entries in the log to 500.
Switch(config)# archiveSwitch(config-archive)# log configSwitch(config-archive-log-cfg)# logging enableSwitch(config-archive-log-cfg)# logging size 500Switch(config-archive-log-cfg)# endThis is an example of output for the configuration log:
Switch# show archive log config allidx sess user@line Logged command38 11 unknown user@vty3 |no aaa authorization config-commands39 12 unknown user@vty3 |no aaa authorization network default group radius40 12 unknown user@vty3 |no aaa accounting dot1x default start-stop group radius41 13 unknown user@vty3 |no aaa accounting system default42 14 temi@vty4 |interface GigabitEthernet4/0/143 14 temi@vty4 | switchport mode trunk44 14 temi@vty4 | exit45 16 temi@vty5 |interface FastEthernet5/0/146 16 temi@vty5 | switchport mode trunk47 16 temi@vty5 | exitConfiguring UNIX Syslog Servers
The next sections describe how to configure the UNIX server syslog daemon and how to define the UNIX system logging facility.
Logging Messages to a UNIX Syslog Daemon
Before you can send system log messages to a UNIX syslog server, you must configure the syslog daemon on a UNIX server. This procedure is optional.
Log in as root, and perform these steps:
Note
Step 1
local7.debug /usr/adm/logs/cisco.logThe local7 keyword specifies the logging facility to be used; see Table 28-4 for information on the facilities. The debug keyword specifies the syslog level; see Table 28-3 for information on the severity levels. The syslog daemon sends messages at this level or at a more severe level to the file specified in the next field. The file must already exist, and the syslog daemon must have permission to write to it.
Step 2
$ touch /var/log/cisco.log$ chmod 666 /var/log/cisco.logStep 3
$ kill -HUP `cat /etc/syslog.pid`For more information, see the man syslog.conf and man syslogd commands on your UNIX system.
Configuring the UNIX System Logging Facility
When sending system log messages to an external device, you can cause the switch to identify its messages as originating from any of the UNIX syslog facilities.
Beginning in privileged EXEC mode, follow these steps to configure UNIX system facility message logging. This procedure is optional.
Step 1
configure terminal
Enter global configuration mode.
Step 2
logging host
Log messages to a UNIX syslog server host by entering its IP address.
To build a list of syslog servers that receive logging messages, enter this command more than once.
Step 3
logging trap level
Limit messages logged to the syslog servers.
Be default, syslog servers receive informational messages and lower. See Table 28-3 for level keywords.
Step 4
logging facility facility-type
Configure the syslog facility. See Table 28-4 for facility-type keywords.
The default is local7.
Step 5
end
Return to privileged EXEC mode.
Step 6
show running-config
Verify your entries.
Step 7
copy running-config startup-config
(Optional) Save your entries in the configuration file.
To remove a syslog server, use the no logging host global configuration command, and specify the syslog server IP address. To disable logging to syslog servers, enter the no logging trap global configuration command.
Table 28-4 lists the UNIX system facilities supported by the software. For more information about these facilities, consult the operator's manual for your UNIX operating system.
Displaying the Logging Configuration
To display the logging configuration and the contents of the log buffer, use the show logging privileged EXEC command. For information about the fields in this display, see the Cisco IOS Configuration Fundamentals Command Reference, Release 15.x.
