What are Interface Statistics and Status in Networking?

Quick Definition: Network interface statistics and statuses help network engineers troubleshoot connectivity issues and optimize network performance by providing information about overall network health. 

A network without connectivity is about as good as a car without gasoline – it’s just a bunch of expensive metal that won’t go very far. To continue with the car metaphor, just as a car comes with warning lights to warn you about issues, network devices provide interface statistics and statuses to give insights into performance and aid in troubleshooting. 

Let's discuss common interface statistics and statuses available to most devices and why those matter. You will also learn how to use those statistics to troubleshoot network issues. All of these are essential components of the CompTIA Network+ certification exam. 

What are the Basics of Interface Statistics and Status?

Starting with the basics, network interface statistics and statuses provide information regarding overall network health. As a network engineer, you can use this information to optimize an already strong network, as well as troubleshoot connectivity issues as they arise. Some common interface statistics and statuses include traffic utilization, error rates, packet discards, and interface status.

• Traffic utilization provides information about the amount of data being sent and received over a specific interface. This should help you establish a baseline for data transmission and identify anomalies.

• Error rates calculate the amount of errors occurring during transmission. This information is useful for troubleshooting anomalies and can help identify configuration issues or hardware malfunctions.

• Packet discards identify when one or more packets are dropped, usually due to configuration issues or network congestion. This information can help you determine whether additional load balancers are needed or whether firewall rules need to be modified on your network. 

• Interface status provides information about an interface’s state. This information can help identify the root cause of a lack of connectivity, such as a network port shutting down. For example, you could use interface status to confirm that a specific port is unconnected because an unauthorized device attempted to connect, triggering port-based network access control policies, also known as PNAC.

Why Does Traffic Utilization Matter?

Traffic utilization is the amount of data being sent and received over a network interface relative to the amount of data that a specific interface can handle. In an ideal world, your network utilization will find a balance between overutilized and underutilized, where there’s not so much traffic passing to overwhelm your network but not so little traffic to waste resources.

Traffic utilization is typically measured in bits per second (bps) and can often also be represented as a percentage of an interface’s total capacity. Many free and paid tools, such as Simple Network Management Protocol (SNMP), SolarWinds Netflow, Nagios, and Dynatrace, can help measure network utilization. The tools you use will depend on your needs and budget. 

Measuring utilization is one thing, but understanding what that utilization means for your network is what drives action. If your network utilization is consistently high, you may need to upgrade equipment and capabilities. If you’re experiencing spikes in utilization, you may be better off looking for patterns to be able to prepare for the next spikes and plan accordingly. 

For example, an online retailer may want to add network capacity around the holidays as more customers are likely to visit the site. Similarly, travel sites may need to scale up capacity during the peak summer travel season and the holidays for the same reason.

If precautions are not implemented, higher network utilization can lead to negative impacts, such as a slow network, packet loss, and, ultimately,  less network availability. You can help mitigate these issues by actively monitoring your network’s interface statistics and statuses and making adjustments to network capacity, firewall rules, and other network configurations when necessary. 

How to Interpret Error Rates

While there are several errors you may encounter, some of the more common errors consist of cyclic redundancy check (CRC) errors, interface resets, and input/output errors. CRC errors typically indicate transmission errors resulting in data corruption. Interface resets are likely the result of misconfigurations or hardware issues, and input/output errors are usually the result of sent and/or received data.

Troubleshooting network errors can be frustrating at times, but you can always start by confirming there are no issues with physical connections. Ensure all cables are in good physical condition and properly seated in the device at both ends. If that all checks out, look at the configurations along the transmission path to verify there are no obvious obstacles to prevent successful transmission. 

Network transmission errors can negatively affect data, user satisfaction, and overall throughput. The higher the error rate, the more likely you are to experience data integrity issues, latency, and overall throughput issues. 

To mitigate these issues, you should regularly patch and update the software on all your networking devices, ensure all your configurations are up-to-date and compatible, practice good cable management, and periodically confirm that your networking hardware is in good physical condition. 

How to Analyze Packet Discards

Packet discards, or dropped packets, directly correlate to error rates. Higher packet discards lead to higher error rates, which can provide you with more troubleshooting opportunities. 

Packet discards occur when an interface is unable to transmit packets due to misconfigurations, network limitations, or hardware issues. Regardless of the root cause, discarded packets increase latency as the network attempts to retransmit the dropped packets.

To help mitigate packet discards, ensure your network’s capabilities align with the expected demand on your network’s equipment. This means you should be monitoring your network’s interface statistics regularly, as well as making any adjustments as necessary. If needed, you can manipulate Quality of Service (QoS) settings to prioritize traffic. It’s important to keep your network operating smoothly and efficiently.

Understanding Interface Status Indicators

When it comes to monitoring interfaces, there are a few common statuses to look out for. The up/down status indicates whether an interface is available; “up” means the interface is available, and “down” means it is not. 

If a network interface unexpectedly goes “down,” you need to investigate and respond accordingly. In addition to up/down status, you should be aware of when network interfaces enter admin status. Admin status indicates when an interface has either been enabled or disabled manually. Network engineers should follow some sort of change management process to communicate before making any changes to the network to help mitigate any confusion.

Some interface statuses may result from mismatched speed or duplex settings, which can lead to network performance issues and increased error rates. All of these interface statuses can help you visualize your network’s overall health and identify the root cause of certain issues. 

When troubleshooting these statuses, be sure to check the health of your equipment, its physical connections, and its configurations. 

What are Some Best Practices for Monitoring Interface Statistics & Status?

Network engineers must proactively monitor network interfaces and statuses to maintain a smooth-running network. Some best practices for this include real-time monitoring tools, automated real-time alerts, regular auditing and maintenance, and configuration management. 

Real-time monitoring tools can help you identify network issues such as changes in interface status, spikes in network utilization, and packet loss. You can also configure automated real-time alerts based on a set of criteria, such as when interface utilization reaches a certain percentage, or when packet loss hits a certain threshold. These automated alerts can help you respond to your network’s needs before performance degrades past a satisfactory limit.

Regular auditing and maintenance are crucial to ensuring your network has the best opportunity to function without issues. Some of the functions you may perform include reviewing network configurations and confirming they align with your network’s needs, and regularly updating the software and firmware of your networking equipment. 

Finally, you should maintain accurate documentation through a configuration management process. This applies to both performing regular maintenance and responding to network performance issues. Documentation should include starting and ending software versions when updating firmware, any automated alerts you may have received, and any troubleshooting you may have performed when recovering from degraded network performance. 

Conclusion

Network interface statistics and statuses provide valuable insight into your network's overall health. You should be able to use each statistic and status to troubleshoot degraded performance. Understanding the real-world application of statistics like network utilization, error rates, and packet loss is essential to becoming a good network engineer and passing the CompTIA Network+ certification exam. 

Check out our CompTIA Network+ Online Certification Training to prepare for the exam and learn the skills to become a better network engineer.