Network Security - QoS

What Is QoS?

QoS (Quality of Service) is a network feature that manages and prioritizes traffic to ensure important applications receive the right amount of bandwidth, low latency, and stable performance.

It ensures that critical services—like video calls, VoIP, online gaming, and business applications—work smoothly even when the network is busy.

Why QoS Is Important

• Prevents network congestion

• Ensures smooth audio/video calls

• Improves performance of essential business apps

• Reduces delays (latency) and jitter

• Guarantees minimum bandwidth for priority tasks

How QoS Works

QoS divides network traffic into different priority levels.
For example:

• High priority → VoIP calls, video conferencing

• Medium priority → Web browsing, emails

• Low priority → Downloads, updates

The network then handles packets according to these priorities.

Key QoS Techniques

1. Traffic Classification

Identifying types of traffic (e.g., voice, video, data).

2. Traffic Prioritization

Assigning priority levels so important traffic gets processed first.

3. Bandwidth Allocation

Reserving minimum bandwidth for critical services.

4. Traffic Shaping

Controlling and smoothing traffic flow to prevent congestion.

5. Queuing and Scheduling

Organizing packets into queues and sending them based on priority.

QoS Performance Metrics

QoS monitors and improves:

• Latency (delay)

• Jitter (variation in delay)

• Packet loss

• Bandwidth availability

Real-World Examples of QoS

• Prioritizing voice calls over file downloads

• Ensuring video streams don’t lag during peak hours

• Giving business applications more bandwidth in corporate networks

• Stabilizing online gaming performance

QoS in Simple Terms

Think of QoS like traffic control on a road:

• Ambulance (critical traffic) → Gets highest priority

• Cars (normal traffic) → Medium

• Trucks (heavy downloads) → Lowest priority

This keeps everything running smoothly.