Network Monitoring - Active vs Passive

If you're running a network, monitoring it is extremely important. It allows you to detect issues before they become bigger problems and help optimize for better performance. However, there are two primary ways of monitoring a network - active and passive. In this blog post, we'll compare the two and help you understand which method is best for your network.

What is Active Monitoring?

Active monitoring involves sending test traffic through the network to see how it performs. For example, an admin can send a ping to a device to see if it responds. Active monitoring is a way to proactively identify and fix network issues by collecting data about response times, packet loss, and traffic characteristics.

Pros:

• Detects network issues before they become significant problems
• Provides real-time insights

Cons:

• May cause network congestion
• Can only test certain types of traffic

What is Passive Monitoring?

Passive monitoring involves collecting and analyzing data from network traffic without affecting it. A network analyzer captures all the data that passes through the network, without any modifications. Passive monitoring helps you understand the network’s behavior, identifying the source and destination of traffic, and providing analytics without disturbing the network.

Pros:

• Can monitor all network activity
• Does not affect the network

Cons:

• Cannot proactively detect network issues
• Only shows information available at the time of data capture

Comparison: Active vs Passive Monitoring

Which is Best for Your Network?

It depends on the specific objectives, resources and design of your network. Active monitoring (ping, traceroute) is ideal for identifying immediate network issues and helps network administrators proactively troubleshoot problems. Passive monitoring (network sniffer, analytics) provides a broader, long-term view of network performance, utilization and trends.

Ultimately, both methods play an important role in the management of a network, and choosing one or the other may limit your visibility, proper responsive action to potential problems, and troubleshooting capacity. A combination of both methods is likely to provide the most complete network visibility and the best chance of preventing issues before they start.

References

1. "Active and Passive Network Monitoring." ScienceSoft Blog, 26 June 2020, https://www.scnsoft.com/blog/active-and-passive-network-monitoring.
2. "Understanding Active and Passive Network Monitoring." ManageEngine OpManager, https://www.manageengine.com/network-monitoring/active-and-passive-monitoring.html.