The increase in CPU consumption on a MikroTik device when using the OSPF (Open Shortest Path First) protocol can vary greatly depending on several factors.

OSPF is a dynamic routing protocol used to manage network routes within an autonomous system. Its impact on the router's CPU depends on:

1. Network Complexity: The more OSPF routes and connections the router has to manage, the higher the CPU usage. This includes the number of interfaces on the router that participate in OSPF and the number of OSPF neighbors that the router has to communicate with.
2. Number of Topology Changes: OSPF responds to changes in network topology by recalculating routes. Frequent recalculations, caused by topology changes or network instability, can significantly increase CPU usage.
3. OSPF configuration: Specific settings, such as the number and size of OSPF areas (in case of multi-area OSPF), and the use of features such as multi-area OSPF, can influence performance and CPU usage.
4. Hardware Capacity: The underlying hardware of the MikroTik router also plays a crucial role. Models with more powerful processors and more RAM can handle OSPF with relatively less impact on CPU usage compared to older or lower-end models.

Practical Evaluation

To specifically determine how much CPU consumption increases due to OSPF, it would be ideal to perform benchmark or monitoring tests in your specific environment.

You can do this using tools like the “Profile” in MikroTik that allows you to see which processes are using the CPU and to what extent:

• Access your MikroTik router: You can do this via WinBox, WebFig or SSH.
• Use the Profile command:
  
  /tool profile
  
  This command displays the percentage of CPU used by each process on the router, including ospf.

Recommendations

If you notice that your CPU usage is consistently high, consider the following actions:

• Optimize OSPF configuration: Adjust timer times, such as Hello and Dead intervals, and consider segmenting the network into smaller OSPF areas to reduce the load.
• Upgrade Hardware: If your router is at capacity, consider upgrading to a more robust model that can better handle the workload.
• Review network topology: Simplifying the network topology can reduce the number of routes that OSPF needs to process, thereby decreasing CPU usage.

Monitoring and adjusting these settings can help manage CPU consumption and ensure OSPF operates efficiently on your MikroTik network.