Network Performance and Bottlenecks

Network Speeds and Congestion

• Predefined Speeds: Networks operate at predefined speeds (e.g., 1 Gbit/s for a gigabit network).
• Congestion Issue: Occurs when multiple 1 Gbit links send traffic to the same destination, exceeding a single link's capacity.
• Buffer Overflow: Switches/routers have small buffers; excess packets may be discarded, leading to data loss.

Resolving Congestion

• Solutions: Increase network size/speed or reduce traffic.
• Misconception: "Network is slow" often indicates a bottleneck somewhere.

Identifying Bottlenecks

• Troubleshooting: Can be complex due to multiple possible causes:
  • System bus speed
  • CPU speed in switches/routers
  • Storage drive speed (HDD vs SSD)
  • Network speed variations
• Example: Database server delay led to 2-second transaction delays; resolved by configuration changes.

Network Usage Metrics

• Bandwidth Percentage: Indicates network use over time.
• Throughput: Amount of data moved through the network in a given timeframe.
• Monitoring Tools: Use switch statistics, SNMP, or NetFlow.

Latency and Measurement

• Latency: Delay between request and response; inherent in all connections.
• Detailed Measurement: Requires tools at each network link to capture packet traversal times.

Packet Loss and Contention

• Impact: Ideal is zero packet loss, but outages or bandwidth issues can cause discards.
• Corruption: Bad cables/wireless networks may corrupt data, causing retransmissions.

Real-Time Communication Challenges

• Voice and Video Sensitivity: Delay can disrupt voice calls or video streams.
• Jitter: Variation in packet arrival times; low jitter is preferred.
• High Jitter Effects: Causes delays, noise in calls, or video stutters.

Understanding these concepts and metrics is crucial for network administrators to maintain efficient and reliable network performance.