Network Performance and Troubleshooting

Network Speed and Congestion

• Network Speed: A 1,000 Base-T gigabit network operates at 1 Gbit/s.

  • Network can’t exceed its predefined speed.
  • Example: Two 1 Gbit links sending traffic at 1 Gbit/s to the same destination can cause congestion.

• Congestion: Occurs when multiple connections send traffic beyond a network’s capacity.

  • Packets queued in a buffer, but buffers in switches/routers are small.
  • Eventually, packets are discarded to maintain system operations.

Resolving Network Issues

• Increase network size/speed or decrease network traffic.
• "Network is slow" often means there's a bottleneck.
  • Bottlenecks can occur due to:
    • System bus speed
    • CPU speed in switches/routers
    • Storage drive speed (HDD vs SSD)
    • Variations in network speed across locations

Troubleshooting Bottlenecks

• Analyze all parameters between devices to find bottlenecks.
• Example of response time issue:
  • Initial response time: ~1500-1750 milliseconds due to database issues.
  • Configuration changes reduced response time to ~500 milliseconds.

Monitoring Network Performance

• Bandwidth Percentage:

  • Indicates network usage over time as a percentage.

• Throughput:

  • Measures data moved through the network over time.

• Tools for monitoring:

  • Direct switch readings
  • SNMP or NetFlow for over-time data collection.

Latency

• Latency: Delay between a request and response.
  • Always present to some degree.
  • Measure response times at every stop for accurate latency assessment.
  • Requires measurement tools at each network link.

Packet Loss

• Ideal: All traffic reaches its destination.
• Packet loss occurs due to:
  • Network outages
  • Insufficient bandwidth
  • Corrupted data from bad connections or wireless issues

Jitter

• Jitter: Variation in time between packet arrivals.
  • Ideally, Jitter is low for consistent packet arrivals.
  • High Jitter can cause delays or issues in:
    • Voice over IP calls (delays/clicks)
    • Live video streams (stutters)

Key Points

• Network congestion and bottlenecks are common issues.
• Understanding and measuring network parameters is crucial to resolving these issues.
• Tools and methods like SNMP, NetFlow, and latency measurement are essential for effective network management.