Monitoring and Troubleshooting

Notes

Ping and traceroute are popular troubleshooting tools on any device, and Junos is no exception. There are some advanced options available though (see the command summary below).

Unlike some other vendors, Juniper rely heavily on log files, rather than just writing to screen. Log files are stored in /var/logs. The messages file, in particular, is very useful.

Often there are so many entries in a log file that it’s hard to find what you need. If you want to see just the most recent entries, show the log, and pipe it through the ‘last’ command.

We can monitor log files with the ‘monitor’ command. This shows the newest log entries on the screen as they are added.

Use match with monitor to filter in real-time.

Traceoptions are like debugs on other vendor devices. They are configured per feature that we want to troubleshoot.

Traceoptions write enties to log files, rather than to the screen, but we can use ‘monitor’ to see the entries on the screen as well.

Redirect traceoptions to a syslog server using destination-override syslog host.

If you want to limit who can access a traceoptions file, use world-readable or no-world-readable.

When logging, add explicit-priority to include syslog levels.

If you need assistance, you will need to call JTAC. It will help if you export logs and other relevant information ahead of time.

Command Summary

Command	Mode	Description
ping IP rapid	Operational	A rapid ping (Cisco style)
ping IP bypass-routing	Operational	Bypass the routing table for a ping
ping IP routing-instance NAME	Operational	Ping using a routing instance
traceroute monitor IP	Operational	Continually monitor a path
request system storage cleanup	Operational	Free up space
show log messages	Operational	Show the messages log
show log FILENAME	Operational	Show any log file
show system boot-messages	Operational	Show system boot logs
monitor start	Operational	Begin monitoring a file in real-time to see changes as they happen
monitor list	Operational	See a list of files being monitored
monitor stop	Operational	Stop monitoring a file
set system syslog host	Configuration	Configure a syslog server
set system syslog … source-address	Configuration	Configure a syslog source IP
set system syslog console	Configuration	Send syslogs to the console
monitor interface	Operational	See interface stats in real-time
monitor interface traffic	Operational	Monitor all interfaces at once
monitor traffic interface	Operational	A tcpdump style packet capture (traffic to the RE)
set … traceoptions file FILENAME flag ITEM	Configuration	Configure traceoptions
show chassis alarms	Operational	See any current alarms
show chassis environment	Operational	Check temperature, fan status, etc
show chassis temperature-thresholds	Operational	Check temperature warning levels
show chassis hardware	Operational	See the hardware in your platform
show chassis fpc	Operational	Get line card details
show chassis cluster	Operational	Get cluster information
show chassis routing-engine	Operational	Get RE details
show system core-dumps	Operational	Collect core-dump information
show system alarms	Operational	Show system alarms
show system boot-messages	Operational	Show messages logged during boot
show system license	Operational	Show licensing information
show system storage	Operational	Show disk usage
show system uptime	Operational	See when the system last booted
show system process extensive	Operational	Show a full list of processes
request system halt	Operational	Power down the system
request system power-off	Operational	Power down the system
request system software add	Operational	Update Junos
request system configuration rescue save	Operational	Update the rescue configuration
request system configuration rescue delete	Operational	Delete the rescue configuration
request chassis routing-engine master switch	Operational	Change over the active RE
request chassis fpc slot NUMBER restart	Operational	Restart a line card
rollback rescue	Configuration	Load the rescue configuration
request support information | save /var/log/FILENAME	Operational	Collect JTAC support information
file archive compress source /var/log/* destination /var/tmp/FILENAME	Operational	Achive support information and logs, ready to be uploaded to JTAC
show chassis craft-interface	Operational	Shows the status of the LCD display on MX routers
set system syslog user USERNAME	Configuration	Send syslog messages to a users terminal (can use regex, facility, and severity to filter)
help syslog	Operational	Get help on syslog messages

Additional References