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March 03, 2025 01:14
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Network Performance Monitoring Cheatsheet
A comprehensive cheat sheet covering key aspects of Network Performance Monitoring (NPM), including metrics, tools, and techniques for maintaining optimal network health and performance.
Key Metrics
Latency
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The time it takes for data to travel from source to destination. |
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Importance: |
High latency can indicate network congestion, routing issues, or slow hardware. |
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Measurement: |
Measured in milliseconds (ms) using tools like ping, traceroute, or specialized NPM solutions. |
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Acceptable Values: |
Varies based on application requirements; real-time applications require very low latency (e.g., < 100ms). |
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Troubleshooting: |
Investigate network paths, optimize routing, upgrade hardware, or implement QoS. |
Packet Loss
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Definition: |
The percentage of packets that fail to reach their destination. |
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Importance: |
High packet loss leads to retransmissions, degraded application performance, and poor user experience. |
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Measurement: |
Monitored using network monitoring tools that track packet transmission and reception rates. |
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Acceptable Values: |
Ideally, packet loss should be close to 0%; values above 1% often indicate a problem. |
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Troubleshooting: |
Check for network congestion, faulty hardware (cables, NICs), or misconfigured network devices. |
Throughput
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Definition: |
The actual rate of data transfer across the network, typically measured in bits per second (bps). |
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Importance: |
Low throughput can bottleneck applications and services, leading to slow performance. |
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Measurement: |
Measured using tools like iperf, speedtest, or network performance monitoring solutions. |
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Acceptable Values: |
Should align with the network’s bandwidth capacity; significant deviations indicate potential issues. |
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Troubleshooting: |
Identify bandwidth bottlenecks, optimize network configurations, or upgrade network infrastructure. |
Tools & Techniques
Ping
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Description: |
A basic utility to test the reachability of a network host. Sends ICMP echo requests and measures round-trip time. |
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Usage: |
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Limitations: |
Limited information beyond reachability and latency; can be blocked by firewalls. |
Traceroute/Tracert
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Description: |
Traces the route taken by packets to reach a destination, showing each hop along the way. |
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Usage: |
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Purpose: |
Identify network bottlenecks or routing issues by examining latency at each hop. |
Network Monitoring Software
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Comprehensive tools that provide real-time monitoring of network devices, traffic, and performance metrics. |
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Examples: SolarWinds Network Performance Monitor, PRTG Network Monitor, Zabbix, Nagios |
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Features often include alerting, reporting, and historical data analysis. |
SNMP (Simple Network Management Protocol)
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Description: |
A protocol used to collect information from and manage network devices. |
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Components: |
SNMP Manager (collects data) and SNMP Agent (runs on network devices and provides data). |
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Uses: |
Monitoring device status, bandwidth utilization, CPU load, and memory usage. |
Advanced Techniques
NetFlow/IPFIX
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Description: |
Network protocols used to collect IP traffic flow information. NetFlow is Cisco’s proprietary protocol, while IPFIX is the standardized version (RFC 7011). |
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Functionality: |
Capture data about network traffic flows, including source/destination IPs, ports, protocols, and volume of traffic. |
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Usage: |
Analyze network traffic patterns, identify bandwidth-intensive applications, and detect security threats. |
sFlow
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Description: |
A sampling-based network monitoring protocol. It randomly samples network packets and sends flow data to a collector. |
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Advantages: |
Lower overhead compared to NetFlow/IPFIX, as it doesn’t track every single flow. |
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Disadvantages: |
Less accurate than NetFlow/IPFIX due to sampling. |
QoS (Quality of Service) Monitoring
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Description: |
Monitoring the effectiveness of QoS policies implemented to prioritize network traffic. |
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Metrics: |
Track packet loss, latency, and jitter for different traffic classes to ensure QoS policies are working as expected. |
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Benefits: |
Ensures critical applications receive the necessary bandwidth and priority. |
Deep Packet Inspection (DPI)
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Examining the contents of network packets to identify applications, protocols, and potentially malicious traffic. |
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Uses: |
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Application identification, intrusion detection, and traffic shaping. |
Best Practices
Baseline Establishment
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Establish a baseline of normal network performance to identify deviations and anomalies. |
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Collect data during periods of normal network activity to understand typical latency, throughput, and packet loss rates. |
Alerting and Thresholds
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Configuration: |
Set up alerts to notify administrators when performance metrics exceed predefined thresholds. |
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Example: |
Alert if latency exceeds 200ms or packet loss exceeds 1%. |
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Importance: |
Proactive notification allows for quick identification and resolution of network issues. |
Regular Reporting
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Generate regular reports on network performance to track trends, identify recurring issues, and demonstrate the value of network monitoring efforts. |
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Include data on latency, throughput, packet loss, and device utilization. |
Capacity Planning
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Purpose: |
Use network performance data to forecast future capacity needs and plan for upgrades or expansions. |
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Considerations: |
Factor in expected growth in network traffic, new applications, and increased user demand. |