When you’re configuring routing protocols on logical systems and something isn’t working as expected, you need proper debugging tools. This video covers how to configure traceoptions log files for OSPF within a logical system and how to monitor them in real time — an essential skill before diving deeper into OSPF and BGP configuration.
Juniper automatically creates a separate log directory for each logical system when it’s created. You can view these from the master instance using show log followed by the logical system name. By default these files are empty, but once you configure traceoptions on a protocol within the logical system, log entries start appearing in the corresponding file automatically.
To enable OSPF tracing within the core logical system we navigate to the protocols ospf hierarchy and use set traceoptions file followed by a filename. In the demonstration we use core-ospf as the filename. Once committed, Juniper writes all OSPF protocol events to this file within the core logical system’s log directory.
The video demonstrates two ways to view the log. From the master instance you can use show log core core-ospf. From within the logical system context you can simply use show log core-ospf and Juniper automatically looks within the correct logical system’s directory. We trigger log entries by clearing OSPF neighbours on the core and watching the adjacency down and up events appear in the file.
Real-time monitoring is covered using the monitor start command, which tails the log file live to the CLI — the equivalent of tail -f on a Linux system. This is particularly powerful when you’re configuring OSPF authentication and want to see authentication failures in real time as they happen rather than checking the log file retrospectively.
The video also shows how to filter the global log messages using show log messages and match to isolate events from a specific logical system, and how to further filter down to the routing daemon using the RPD identifier. These techniques significantly speed up troubleshooting in complex multi-logical-system topologies.