Welcome to the final installment of our “Introduction to Juniper and JNCIA” series. In this article, we will explore essential tips and tricks for monitoring and troubleshooting Junos devices. Whether you are a seasoned technology engineer or an aspiring enthusiast, this guide will equip you with valuable insights to enhance your understanding of Juniper routers and switches. So, let’s dive right in!
Contents
Ping and Trace Frame
Let’s begin with two handy tools: ping and trace frame. The ping command in Junos provides a Linux-style output and runs continuously until manually stopped. For a similar result to the Cisco approach, you can use the “rapid” keyword, which sends five quick pings. If you want to bypass the routing table and use a specific interface, simply add the “bypass-routing” keyword.
Now, here’s the really awesome part. Try using the traceroute command with the “monitor” option. This command continuously monitors the path to a destination, making it incredibly useful for tracking packet loss or high latency. Pressing the “space” key allows you to toggle between different views.
Logging and Monitoring
Junos is heavily based on FreeBSD and Linux, which means there are several methods for logging. Similar to Linux, Junos has a vast log directory, and the most important log file is the “messages” log. You can view the contents of any log file using the “show log” command and see the most recent entries by piping it through the “last” command.
The boot process is also logged, and you can view the system boot messages using the “show system boot messages” command. To monitor log files in real-time, you can use the “monitor” command, which displays new additions to the screen. This is akin to using the Terminal Monitor command in iOS or the “tail -f” command in Linux.
Exporting Logs and Syslog Settings
Junos allows you to export logs to an external syslog server or configure logging settings locally or remotely. Under the “system syslog” hierarchy, you can set up syslog hosts, facilities, and logging levels. To send messages to the console port, use caution and only do so during troubleshooting. The “help syslog” command provides additional information on log messages and their meanings.
Interface Monitoring
Monitoring interfaces is crucial for assessing their performance. You can use the “monitor interface” command to view real-time statistics and determine if an interface is being overused or experiencing packet drops. Alternatively, the “monitor interface traffic” command provides a real-time summary of all interfaces by default, showing packet counters. To switch to bandwidth, press “b”.
For more advanced monitoring, the “monitor traffic interface” command is similar to tcpdump in Linux and captures exceptional traffic. However, it cannot capture transit traffic. If you find the output too overwhelming, add the “write file” command to save it to disk. You can later review the results using the “monitor traffic read file” command.
Trace Options
Trace options in Junos are similar to the debug feature in iOS, but the output is written to disk rather than displayed on screen. This improves performance. Each feature in the configuration can have trace options enabled. To enable trace options for an interface, you’ll need to set the file to write to, and then specify the desired flags. Flags vary depending on the feature. In this example, we enable all flags for simplicity.
You can view the collected logs using the “show log” command. To monitor these logs in real-time, use the “monitor” command and add filters using the “match” option. Log files will eventually reach a maximum size and rotate. The most recent logs can be found by piping the output through the “last” command.
FAQs
Q: How can I export Junos logs to an external syslog server?
A: To export logs to an external syslog server, configure the syslog host IP, facility, and logging level in the “system syslog” hierarchy.
Q: Can I monitor Junos interfaces in real-time?
A: Yes, you can use the “monitor interface” command to view real-time interface statistics and assess performance.
Q: How can I enable trace options in Junos?
A: Trace options can be enabled for various features by specifying the file to write to and setting the desired flags.
Conclusion
Congratulations! You’ve reached the end of our “Introduction to Juniper and JNCIA” series. We hope that this comprehensive guide to Junos monitoring and troubleshooting has provided you with valuable insights and tips. Whether you’re preparing for the exam or embarking on a career working with Juniper routers and switches, we wish you the best of luck. If you enjoyed this series, don’t forget to subscribe for updates on future content.
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