How to Monitor Network Traffic: A Technical Guide to Effective Network Performance Monitoring

Monitoring network traffic is a crucial component of maintaining a healthy IT infrastructure. Whether you’re responsible for a small office network or a large enterprise system, having clear visibility into your network’s performance can help you identify bottlenecks, troubleshoot issues, and improve security. In this article, we’ll discuss the technical steps to monitor network traffic effectively using some of the best tools available in the industry, including PRTG Network Monitor and general Network Traffic Monitors.

What is Network Traffic?

Network traffic refers to the amount of data moving across a computer network, broken down into data packets and sent via north-south and east-west directions. High traffic can affect network quality and security, potentially indicating an attack.

Data packets

Data sent via networks, or the internet is divided into smaller batches for efficient transfer of larger files. The network organizes and bundles data into packets, ensuring reliable transfer and equitable network traffic distribution by taking the most efficient route.

North-south traffic

North-south traffic refers to client-to-server traffic that moves between the data center and the rest of the network (i.e., a location outside of the datacenter).

East-west traffic

East-west traffic refers to traffic within a data center, also known as server-to-server traffic.

Types of Network Traffic

Effective network traffic management requires distinguishing between real-time and non-real-time traffic. This allows network administrators to prioritize critical applications and ensure optimal performance while minimizing delays and congestion.

Real-Time Traffic: Ensuring Priority for Critical Applications

Real-time traffic refers to data that needs immediate delivery with minimal delay, as delays can severely affect its quality. This traffic is prioritized to guarantee that business-critical applications are always available and perform optimally.

Examples of Real-Time Traffic:

• VoIP (Voice over IP): Requires low latency to prevent poor call quality.
• Video Conferencing: Needs consistent, uninterrupted data flow to maintain video and audio quality.
• Web Applications: Critical business apps that require instant access, such as ERP systems or cloud-based software.

Key Characteristics:

• Low Latency: Quick delivery is essential.
• Minimal Jitter: Variability in packet arrival time should be minimized.
• High Availability: Services need to be always on.
• Sensitive to Packet Loss: Even small amounts of data loss can degrade performance.

Non-Real-Time Traffic: Best-Effort Communication

Non-real-time traffic (or best-effort traffic) is less time-sensitive and can tolerate delays. While still important, it doesn’t require the same level of urgency as real-time traffic.

Examples of Non-Real-Time Traffic:

• FTP (File Transfer Protocol): Used for file uploads or web publishing, can tolerate delays.
• Email: Delays are not critical to business operations.
• Software Updates/Backups: Large data transfers that can be scheduled for off-peak hours.
• Cloud Syncing: File syncing across devices, not time dependent.

Key Characteristics:

• Higher Latency Tolerance: Delays don’t significantly impact performance.
• Buffered or Stored Data: Can be delayed without issues.
• Less Impact from Packet Loss: Some loss is acceptable.
• Scalable: Can be scheduled or spread out over time.

Techniques for Managing Traffic:

1. Quality of Service (QoS): Prioritizes real-time over non-real-time traffic to avoid performance degradation.
2. Traffic Shaping: Controls data flow to prevent congestion and ensure real-time traffic is prioritized.
3. Traffic Scheduling: Non-real-time traffic (e.g., backups) can be scheduled during off-peak hours to minimize impact.
4. Bandwidth Allocation: Allocates bandwidth for real-time traffic, ensuring critical applications always have the necessary resources.
5. Congestion Management: During network congestion, real-time traffic is given priority, and non-real-time traffic may be delayed or dropped.

Key Tools for Network Traffic Monitoring

There are numerous tools available for network traffic monitoring, each with its own features, strengths, and capabilities. We’ll focus on the following tools:

• PRTG Network Monitor: A comprehensive, easy-to-use network monitoring tool.
• Network Traffic Monitor: A broad category of tools that offer detailed insights into bandwidth utilization and traffic flow.

Let’s explore these network traffic monitoring tools and the steps on how to use them.

1. How to Set Up and Use PRTG Network Monitor for Network Traffic Monitoring

PRTG Network Monitor is one of the most popular tools for monitoring network traffic. It provides an all-in-one solution for tracking bandwidth usage, monitoring network performance, and detecting security threats.

The following are the steps on set up monitor network traffic:

Step 1: Install PRTG Network Monitor:

• Download the PRTG Network Monitor from the official website and run the
• Once installed, launch PRTG. The first time you open PRTG, it will automatically detect network devices using auto-discovery.

Step 2: Configure Device Discovery:

• In PRTG, click on the Auto-Discovery button. This feature scans your network for devices like routers, switches, and servers.
• PRTG will add all detected devices to your dashboard for monitoring. If you want to monitor specific devices, you can manually add them using their IP addresses or hostnames.

Step 3: Set Up Traffic Monitoring Sensors:

• PRTG uses sensors to monitor network devices and interfaces. For network traffic monitoring, you’ll want to use NetFlow, sFlow, or SNMP sensors.
• 1. NetFlow and sFlow are flow-based monitoring protocols that capture network traffic data and give you visibility into bandwidth usage, applications, and
• 2. SNMP (Simple Network Management Protocol) allows PRTG to fetch data such as interface traffic, device performance, and other relevant metrics.

• To add a sensor, do these steps:
• 1. Select the device you want to monitor (e.g., router or switch).
• 2. Click on Add Sensor and choose the sensor type (NetFlow, sFlow, or SNMP Traffic Sensor).
• 3. Configure the sensor based on your needs. For example, if using NetFlow, enter the relevant port and interface data for the device.

Step 4: Create Dashboards and Alerts:

• PRTG allows you to set up custom dashboards to visualize traffic data, such as bandwidth usage per interface.
• You can also configure alerts to notify you via email, SMS, or push notifications if traffic exceeds certain thresholds.

Step 5: Analyze Traffic Data:

• Once the sensors are set up, PRTG begins monitoring network traffic in real-time. You can access historical data, generate reports, and visualize traffic trends to identify potential issues.

2. General Network Traffic Monitoring Using SNMP and Flow Protocols

For a broader approach to network traffic monitoring, many organizations rely on SNMP and flow-based monitoring protocols like NetFlow and sFlow. These protocols allow you to monitor traffic data across all network devices, regardless of the monitoring tool you’re using. Below are the steps for setting up a basic network traffic monitor using SNMP and flow protocols.

Step 1: Enable SNMP on Network Devices:

• SNMP is widely supported across most network devices (routers, switches, firewalls, etc.). To enable SNMP, log into your device’s management interface (e.g., web UI or command-line interface).
• For example, on Cisco devices, you can enable SNMP after entering the following commands:
• 1. (config)# snmp-server community public RO
• 2. (config)# snmp-server enable traps

Step 2: Configure NetFlow or sFlow:

• NetFlow and sFlow are flow-based protocols that capture data about network traffic flows, such as source and destination IP addresses, traffic volume, and application types.
• To enable NetFlow on a Cisco device, use the following examples:
• 1. (config)# flow-export destination
• 2. (config)# flow-export version 9
• 3. (config)# ip flow ingress
• This will start exporting flow data to your NetFlow collector (such as PRTG or TRTG).

Step 3: Set Up Traffic Monitoring Tools:

• Use your network traffic monitor to pull in SNMP, NetFlow, or sFlow data and display it in a usable format. Popular tools, like PRTG Network Monitor and Zabbix, support these protocols natively.

Step 4: Monitor and Analyze Traffic:

• With SNMP, NetFlow, or sFlow data, you can start monitoring:
• 1. Bandwidth usage on specific interfaces.
• 2. Top talkers (devices consuming the most bandwidth).
• 3. Traffic distribution by application or protocol.

Best Practices for Network Traffic Monitoring:

1. Set Thresholds and Alerts: Always configure alerts for high traffic thresholds. This will help you respond to congestion or security threats before they impact performance
2. Monitor Traffic Regularly: Continuous monitoring is key to identifying issues early. Use historical data to spot trends and forecast future network needs.
3. Ensure Compliance: If you’re in a regulated industry, make sure your network traffic monitoring tool is configured to meet compliance requirements, including logging and reporting.
4. Optimize Bandwidth: By analyzing traffic data, identify which applications are consuming the most bandwidth and consider optimizations, such as implementing QoS (Quality of Service) or deploying additional bandwidth.

Conclusion

Monitoring network traffic is essential for maintaining a secure, optimized, and well-performing network. Tools like PRTG Network Monitor, TRTG Network Monitor, and general network traffic monitors provide real-time visibility into bandwidth usage, network performance, and security threats. By following the technical steps outlined in this article, you can successfully set up a robust network monitoring system that helps you detect issues, optimize performance, and improve security. Whether you’re managing a small office network or a large enterprise infrastructure, effective network performance monitoring will help ensure smooth operations and better decision-making for your network.

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References:

1. PRTG Network Monitor (https://www.paessler.com/prtg)
2. NetFlow Protocol – Cisco documentation on NetFlow (https://www.cisco.com/c/en/us/td/docs/ios-xml/ios/netflow/configuration/xe-3s/netflow-xe-3s-book/netflow-overview.html)
3. sFlow Protocol (http://www.sflow.org/)
4. SNMP Protocol – Understanding SNMP (https://www.networkworld.com/article/2904060/how-snmp-works.html)
5. Types of Network Traffic (https://www.fortinet.com/resources/cyberglossary/network-traffic)