Troubleshooting guide of OSPF

Contents

Objective

Requirements

Introduction

Troubleshooting Steps

Troubleshooting Commands (“show” commands)

System Log (syslog)

Conclusion

FAQ

Objective

This guide introduces common troubleshooting processes and techniques that can be used to identify the causes of network failures caused by the OSPF module.

Requirements

• Omada and Omada Pro L3 Switch series
• Omada Controller (Software Controller / Hardware Controller / Cloud-Based Controller, v5.9 and above)

Introduction

This article mainly introduces how to monitor OSPF to ensure its normal operation, as well as the troubleshooting measures to take when OSPF fails. It introduces the “show” commands used to monitor OSPF, which can help you understand the running status of OSPF. Besides, it introduces how to use system logs, which can facilitate fault analysis.

Troubleshooting Steps

Effective monitoring of the OSPF running status is crucial for network operations. Real-time monitoring of the status of devices and routing protocols can help troubleshoot faults and ensure network availability for all users.

Troubleshooting Commands (“show” commands)

The “show” commands can help check the OSPF status, which is convenient for analyzing and locating the causes of faults. You can use the "?" in the CLI interface to use the Help function, and the figure below shows the list of available commands after running the "show ip ospf ?" command.

• show ip ospf

Note: Display the global information of the OSPF process.

With the "show ip ospf" command, you can check the general information of the entire OSPF routing process.

• show ip ospf database

Note: Display the LSDB summary information.

With the "show ip ospf database" command, you can check the summary of the link state database maintained by the device. This command displays the router ID and process ID, and the use of the easily identifiable RID can be more intuitive to identify the specific device in the troubleshooting process. The information displayed by using this command is hierarchical according to the OSPF process, OSPF area, and different types of LSAs within the OSPF area, as shown in the figure below.

• show ip ospf interface

Note: Display the interface information.

With the "show ip ospf interface" command, you can check the OSPF-related interface information. You can specify a specific interface at the end of this command. If no interface parameter is added, this command will output the information of all interfaces participating in the OSPF process.

With this command, you can verify whether the specific interface is configured in the correct area, as shown in the figure below.

• show ip ospf neighbor

Note: Display the information of OSPF neighbors.

With the "show ip ospf neighbor" command, you can obtain the summary of OSPF neighbors. You can use the "detail" parameter to view the detailed information of the neighbors, and this command also supports filtering and display by interface, as shown in the figure below.

The figure below shows the output of the "show ip ospf neighbor" command without specifying any parameters, which displays all neighbors and the interfaces where the neighbors are discovered.

• show ip ospf route

Note: Display the OSPF routing table.

With the "show ip ospf route" command, you can check the OSPF routing information that has been calculated and optimized by the OSPF process, as shown in the figure below.

• show ip ospf border-routers

Note: Display the routing table of the ABR/ASBR.

With the "show ip ospf border-routers" command, you can check the OSPF internal routing entries to the area border routers (ABR) and autonomous system border routers (ASBR), as shown in the figure below.

• clear ip ospf.

Note: Reset the OSPF process, which will clear all the dynamic information.

The “clear ip ospf process” command will reset all the OSPF processes. During the troubleshooting process, you may need to clear the OSPF process. The figure below shows the currently supported clearing options.

In some special cases, you can use the "clear ip ospf process" command to completely reset the OSPF process. You can specify the process ID to reset the corresponding process. If no process ID is specified, all OSPF processes on the device will be cleared and reset. As shown in the figure below, executing the process clearing will cause all neighbors to disconnect, and therefore may interrupt the OSPF route selection until OSPF converges again, which may disconnect the management session. Please use it with caution.

System Log (syslog)

The system log is an effective troubleshooting tool, as it can record and track key events in the device's operation. Log information is useful for network analysis, evidence gathering, and troubleshooting. The currently supported recording methods are as follows.

Step 1. Set the system time.

The system automatically timestamps the logs when recording them, and the date and timestamp are usually the best way to verify timing issues. You need to pre-set the system time to ensure that the system can record the correct timestamp when logging, which facilitate fault analysis.

We recommend that you use the Network Time Protocol (NTP) to synchronize the system clocks of all devices. You can use the "system-time ntp" command to specify the NTP server address used for time synchronization, as shown in the figure below.

Step 2. Specify the log level.

Determine the levels of the logs to be recorded. We provide eight log levels. The command to configure the log level is as follows.

Table 1. Syslog Message Severities

Numerical Code	Facility
0	Emergency: system is unusable
1	Alert: action must be taken immediately
2	Critical: critical conditions
3	Error: error conditions
4	Warning: warning conditions
5	Notice: normal but significant condition
6	Informational: informational messages
7	Debug: debug-level messages

Step 3. View the log information.

Run the "show logging" command to view the historical log information, as shown in the figure below.

Step 4. Save logs to the device cache.

In the global configuration mode, run the "logging buffer" command to save logs to the internal cache of the device. The internal cache is a circular storage space. When the cache space is full, the latest log information will overwrite the earliest.

Step 5. Save logs to the system log server.

In the global configuration mode, run the "logging host" command to set the system log server that will receive logs. With the system log server, you can centrally store and completely record the time and details of system events, which facilitate troubleshooting.

Step 6. Record OSPF neighbor state changes.

Most OSPF faults are caused by OSPF routers losing communication with their neighbor routers. Therefore, recording and analyzing the changes in OSPF neighbor status can help with fault troubleshooting. As shown in the figure, in OSPF process mode, run the "log-adjacency-changes" command to record the OSPF neighbor state changes in the syslog information.

Conclusion

This article introduces the common OSPF troubleshooting methods. With the help of the "show" commands and the system log, most network problems can be solved. If you need more assistance, please collect the information and contact the TP-Link Support.

Get to know more details of each function and configuration please go to Download Center to download the manual of your product.

FAQ

How can I use CLI commands to view OSPF entries in the Controller mode?

Re. In the Site view, go to Tools > Terminal, select the corresponding switch, and click Open Terminal.