You can use system message logging to control the
destination and to filter the severity level of messages that system processes
generate. You can configure logging to terminal sessions, a log file, and
syslog servers on remote systems.
By default, the
Cisco Nexus 5000 Series switch outputs messages to terminal sessions.
By default, the switch logs system messages to a
log file.
The following table describes the severity levels
used in system messages. When you configure the severity level, the system
outputs messages at that level and lower.
Table 1 System Message Severity Levels
Level
Description
0 – emergency
System unusable
1 – alert
Immediate action needed
2 – critical
Critical condition
3 – error
Error condition
4 – warning
Warning condition
5 – notification
Normal but significant condition
6 – informational
Informational message only
7 – debugging
Appears during debugging only
The switch logs the most recent 100 messages of
severity 0, 1, or 2 to the NVRAM log. You cannot configure logging to the
NVRAM.
You can configure which system messages should be
logged based on the facility that generated the message and its severity level.
syslog servers run on remote systems that are configured to log system
messages based on the syslog protocol. You can configure the
Cisco Nexus 5000 Series
to sends its logs to up to three syslog servers.
To support the same configuration of syslog servers on all switches in
a fabric, you can use the Cisco Fabric Services (CFS) to distribute the syslog
server configuration.
Note
When the switch first initializes, messages are sent to syslog
servers only after the network is initialized.
Configuring System Message Logging
Configuring System Message Logging to Terminal Sessions
You can configure the switch to log messages by their severity level
to console, Telnet, and SSH sessions.
By default, logging is enabled for terminal sessions.
Procedure
Command or Action
Purpose
Step 1
switch#
terminal monitor
Copies syslog messages from the console to the current terminal
session.
Step 2
switch#
configure terminal
Enters configuration mode.
Step 3
switch(config)#
logging console [severity-level]
Enables the switch to log messages to the console session based on
a specified severity level or higher (a lower number value indicates a higher
severity level). Severity levels range from 0 to 7:
0 – emergency
1 – alert
2 – critical
3 – error
4 – warning
5 – notification
6 – informational
7 – debugging
If the severity level is not specified, the default of 2 is used.
Step 4
switch(config)#
no logging console [severity-level]
(Optional)
Disables logging messages to the console.
Step 5
switch(config)#
logging monitor [severity-level]
Enables the switch to log messages to the monitor based on a
specified severity level or higher (a lower number value indicates a higher
severity level). Severity levels range from 0 to 7:
0 – emergency
1 – alert
2 – critical
3 – error
4 – warning
5 – notification
6 – informational
7 – debugging
If the severity level is not specified, the default of 2 is used.
The configuration applies to Telnet and SSH sessions.
Step 6
switch(config)#
no logging monitor [severity-level]
(Optional)
Disables logging messages to telnet and SSH sessions.
Step 7
switch#
show logging console
(Optional)
Displays the console logging configuration.
Step 8
switch#
show logging monitor
(Optional)
Displays the monitor logging configuration.
Step 9
switch#
copy running-config startup-config
(Optional)
Copies the running configuration to the startup configuration.
The following example shows how to configure a logging level of 3 for
the console:
switch# configure terminal
switch(config)# logging console 3
The following example shows how to display the console logging
configuration:
switch# show logging console
Logging console: enabled (Severity: error)
The following example shows how to disable logging for the console:
switch# configure terminal
switch(config)# no logging console
The following example shows how to configure a logging level of 4 for
the terminal session:
switch# terminal monitor
switch# configure terminal
switch(config)# logging monitor 4
The following example shows how to display the terminal session
logging configuration:
switch# show logging monitor
Logging monitor: enabled (Severity: warning)
The following example shows how to disable logging for the terminal
session:
switch# configure terminal
switch(config)# no logging monitor
Configuring System Message Logging to a
File
You can configure the switch to log system messages
to a file. By default, system messages are logged to the file log:messages.
Configures the name of the log file used to
store system messages and the minimum severity level to log. You can optionally
specify a maximum file size. The default severity level is 5 and the file size
is 4194304.
Severity levels range from 0 to 7:
0 – emergency
1 – alert
2 – critical
3 – error
4 – warning
5 – notification
6 – informational
7 – debugging
The file size is from 4096 to 10485760 bytes.
Step 3
switch(config)#
no logging logfile
[logfile-nameseverity-level [sizebytes]]
(Optional)
Disables logging to the log file.
Step 4
switch#
show logging info
(Optional)
Displays the logging configuration.
Step 5
switch#
copy running-config
startup-config
(Optional)
Copies the running configuration to the startup
configuration.
The following example shows how to configure a
switch to log system messages to a file:
Enables logging messages from the specified facility that have the
specified severity level or higher. Severity levels from 0 to 7:
0 – emergency
1 – alert
2 – critical
3 – error
4 – warning
5 – notification
6 – informational
7 – debugging
To apply the same severity level to all facilities, use the
all facility. For defaults, see the
show logging level command.
Step 4
switch(config)#
no logging module
[severity-level]
(Optional)
Disables module log messages.
Step 5
switch(config)#
no logging level [facility
severity-level]
(Optional)
Resets the logging severity level for the specified facility to
its default level. If you do not specify a facility and severity level, the
switch resets all facilities to their default levels.
Step 6
switch#
show logging module
(Optional)
Displays the module logging configuration.
Step 7
switch#
show logging level [facility]
(Optional)
Displays the logging level configuration and the system default
level by facility. If you do not specify a facility, the switch displays levels
for all facilities.
Step 8
switch#
copy running-config startup-config
(Optional)
Copies the running configuration to the startup configuration.
The following example shows how to configure the severity level of
module and specific facility messages:
switch# configure terminal
switch(config)# logging module 3
switch(config)# logging level aaa 2
Configuring Logging Timestamps
You can configure the time-stamp units of messages logged by the
Cisco Nexus 5000 Series
switch.
Configures a syslog server at the specified
host name or IPv4 or IPv6 address. You can limit logging of messages with a
minimum severity level and for a specific facility. Severity levels range from
0 to 7:
0 – emergency
1 – alert
2 – critical
3 – error
4 – warning
5 – notification
6 – informational
7 – debugging
The default outgoing facility is local7.
Step 3
switch(config)#
no logging serverhost
(Optional)
Removes the logging server for the specified
host.
Step 4
Step 5
switch#
show logging server
(Optional)
Displays the syslog server configuration.
Step 6
switch#
copy running-config
startup-config
(Optional)
Copies the running configuration to the startup
configuration.
The following example shows how to configure a
syslog server:
switch# configure terminal
switch(config)# logging server 172.28.254.254 5 use-vrf VRFname facility local3
You can configure a syslog server on a UNIX or
Linux system by adding the following line to the /etc/syslog.conf file:
facility.level <five tab characters> action
The following table describes the syslog fields
that you can configure.
Table 2 syslog Fields in syslog.conf
Field
Description
Facility
Creator of the message, which can be auth,
authpriv, cron, daemon, kern, lpr, mail, mark, news, syslog, user, local0
through local7, or an asterisk (*) for all. These facility designators allow
you to control the destination of messages based on their origin.
Note
Check your configuration before using a
local facility.
Level
Minimum severity level at which messages
are logged, which can be debug, info, notice, warning, err, crit, alert, emerg,
or an asterisk (*) for all. You can use none to disable a facility.
Action
Destination for messages, which can be a
filename, a host name preceded by the at sign (@), or a comma-separated list of
users or an asterisk (*) for all logged-in users.
Procedure
Step 1
Log debug messages with the local7
facility in the file /var/log/myfile.log by adding the following line to the
/etc/syslog.conf file:
debug.local7 /var/log/myfile.log
Step 2
Create the log file by entering these
commands at the shell prompt:
$ touch /var/log/myfile.log
$ chmod 666 /var/log/myfile.log
Step 3
Make sure the system message logging
daemon reads the new changes by checking myfile.log after entering this
command:
$ kill -HUP ~cat /etc/syslog.pid~
Configuring syslog Server Configuration Distribution
You can distribute the syslog server configuration
to other switches in the network by using the Cisco Fabric Services (CFS)
infrastructure.
After you enable syslog server configuration
distribution, you can modify the syslog server configuration and view the
pending changes before committing the configuration for distribution. As long
as distribution is enabled, the switch maintains pending changes to the syslog
server configuration.
Note
If the switch is restarted, the syslog server
configuration changes that are kept in volatile memory may be lost.
Before You Begin
You must have configured one or more syslog
servers.
Procedure
Command or Action
Purpose
Step 1
switch#
configure terminal
Enters configuration mode.
Step 2
switch(config)#
logging distribute
Enables distribution of syslog server
configuration to network switches using the CFS infrastructure. By default,
distribution is disabled.
Step 3
switch(config)#
logging commit
Commits the pending changes to the syslog
server configuration for distribution to the switches in the fabric.
Step 4
switch(config)#
logging abort
Cancels the pending changes to the syslog
server configuration.
Step 5
switch(config)#
no logging distribute
(Optional)
Disables distribution of syslog server
configuration to network switches using the CFS infrastructure. You cannot
disable distribution when configuration changes are pending. See the
logging
commit and
logging
abort commands. By default, distribution is disabled.
Step 6
switch#
show logging pending
(Optional)
Displays the pending changes to the syslog
server configuration.
Step 7
switch#
show logging
pending-diff
(Optional)
Displays the differences from the current
syslog server configuration to the pending changes of the syslog server
configuration.
Step 8
switch#
show logging internal
info
(Optional)
Displays information about the current state of
syslog server distribution and the last action taken.
Step 9
switch#
copy running-config
startup-config
(Optional)
Copies the running configuration to the startup
configuration.
Displaying and Clearing Log Files
You can display or clear messages in the log file and the NVRAM.
Procedure
Command or Action
Purpose
Step 1
switch#
show logging lastnumber-lines
Displays the last number of lines in the logging file. You can
specify from 1 to 9999 for the last number of lines.
Displays the messages in the log file that have a time stamp
within the span entered. If you do not enter an end time, the current time is
used. You enter three characters for the month time field, and digits for the
year and day time fields.
Step 3
switch#
show logging nvram [lastnumber-lines]
Displays the messages in the NVRAM. To limit the number of lines
displayed, you can enter the last number of lines to display. You can specify
from 1 to 100 for the last number of lines.
Step 4
switch#
clear logging logfile
Clears the contents of the log file.
Step 5
switch#
clear logging nvram
Clears the logged messages in NVRAM.
The following example shows how to display messages in a log file:
switch# show logging last 40
switch# show logging logfile start-time 2007 nov 1 15:10:0
switch# show logging nvram last 10
The following example shows how to clear messages in a log file:
switch# clear logging logfile
switch# clear logging nvram
Verifying System Message Logging Configuration
To display system message logging configuration information, perform
one of the following tasks:
Command
Purpose
switch#
show logging console
Displays the console logging configuration.
switch#
show logging info
Displays the logging configuration.
switch#
show logging internal info
Displays the syslog distribution information.
switch#
show logging lastnumber-lines
Displays the last number of lines of the log file.
switch#
show logging level [facility]
Displays the facility logging severity level configuration.
switch#
show logging logfile [start-timeyyyymmmddhh:mm:ss] [end-timeyyyymmmddhh:mm:ss]
Displays the messages in the log file.
switch#
show logging module
Displays the module logging configuration.
switch#
show logging monitor
Displays the monitor logging configuration.
switch#
show logging nvram [lastnumber-lines]
Displays the messages in the NVRAM log.
switch#
show logging pending
Displays the syslog server pending distribution
configuration.
switch#
show logging pending-diff
Displays the syslog server pending distribution
configuration differences.
switch#
show logging server
Displays the syslog server configuration.
switch#
show logging session
Displays the logging session status.
switch#
show logging status
Displays the logging status.
switch#
show logging timestamp
Displays the logging time-stamp units configuration.
Default System Message Logging Settings
The following table lists the default settings for system message
logging parameters.