🌟 What is Quality of Service (QoS)?

QoS refers to a network’s ability to provide predictable service quality β€” essential for real-time and critical applications (VoIP, video streaming, online gaming).

It focuses on managing network resources to meet performance requirements.

πŸ“ Key QoS Metrics

  1. Bandwidth – Data transfer capacity of the network.
  2. Delay (Latency) – Time for a packet to reach the destination.
  3. Jitter – Variation in delay; critical for media quality.
  4. Packet Loss – Percentage of packets that fail to reach destination.

πŸ›  Mechanisms to Ensure QoS

  • Traffic Classification and Prioritization

    • Differentiated Services (DiffServ)
    • Integrated Services (IntServ)

  • Traffic Shaping

    • Regulates flow to reduce bursts (e.g., token bucket, leaky bucket).

  • Resource Reservation

    • RSVP (Resource Reservation Protocol) in IntServ architecture.

  • Queuing Disciplines

    • FIFO, Priority Queuing, Weighted Fair Queuing (WFQ)

πŸ’‘ Real-world Example

In a video call:

  • Bandwidth ensures smooth visuals.
  • Low delay ensures no lag.
  • Low jitter ensures voice/video sync.
  • No packet loss ensures quality and intelligibility.

🧠 Insights

  • QoS turns β€œbest-effort” networks into deterministic performance zones.
  • Vital for enterprise networks, ISPs, and any delay-sensitive service.
  • Proper congestion control enables QoS; they are tightly coupled.

πŸ§ͺ Wireshark Tip

Use Wireshark to monitor:

  • Delay variation
  • Packet reorderings
  • DSCP field in IP header (used in DiffServ QoS)

πŸ”— Links