Traffic Shaping and QoS

Traffic Shaping and Quality of Service (QoS) are essential techniques for managing network traffic to ensure optimal performance and reliability. This page will cover seven key concepts: Traffic Shaping, QoS Models, Classification, Marking, Policing, Queuing, and Scheduling.

1. Traffic Shaping

Traffic Shaping is a technique used to control the rate at which traffic is sent or received over a network. It helps to prevent congestion and ensures that critical applications receive the necessary bandwidth.

For example, a business might use Traffic Shaping to limit the bandwidth used by non-critical applications like file sharing, ensuring that critical applications like VoIP and video conferencing receive sufficient bandwidth.

Think of Traffic Shaping as a traffic cop directing cars to ensure smooth flow on a busy road. By controlling the flow, the cop prevents congestion and ensures that emergency vehicles can pass through quickly.

2. QoS Models

QoS Models define how network resources are allocated to different types of traffic. Common models include Best Effort, Integrated Services (IntServ), and Differentiated Services (DiffServ).

Best Effort is the default model where all traffic is treated equally. IntServ provides guaranteed bandwidth for specific applications, while DiffServ classifies traffic into different priority levels.

Imagine QoS Models as different types of lanes on a highway. Best Effort is like a single lane where all cars move at the same speed. IntServ is like a dedicated lane for VIPs, while DiffServ is like multiple lanes with different speed limits for different types of vehicles.

3. Classification

Classification is the process of identifying and categorizing network traffic based on specific criteria, such as source IP, destination IP, port number, or protocol type.

For example, a network administrator might classify VoIP traffic separately from web browsing traffic to ensure that VoIP receives higher priority.

Think of Classification as sorting mail at a post office. By categorizing mail based on destination, the post office ensures that important packages are delivered first.

4. Marking

Marking involves tagging packets with specific QoS markings, such as DSCP (Differentiated Services Code Point) or 802.1p, to indicate their priority level.

For instance, a network might mark VoIP packets with a high DSCP value to ensure they receive priority treatment in the network.

Think of Marking as labeling packages with priority tags at a shipping company. By marking packages, the company ensures that high-priority items are handled first.

5. Policing

Policing is the process of monitoring and controlling the rate of traffic to ensure it does not exceed a specified limit. It helps to prevent congestion and maintain network performance.

For example, a network might police P2P file sharing traffic to ensure it does not consume more than 10% of the total bandwidth.

Think of Policing as a speed limit on a road. By enforcing the limit, the police ensure that traffic flows smoothly and prevent accidents caused by excessive speed.

6. Queuing

Queuing involves managing the order in which packets are transmitted over the network. Different queuing algorithms, such as FIFO (First In, First Out), PQ (Priority Queuing), and WFQ (Weighted Fair Queuing), can be used to prioritize traffic.

For instance, a network might use PQ to ensure that VoIP packets are transmitted before web browsing packets.

Think of Queuing as a line at a grocery store. By managing the order of customers, the cashier ensures that high-priority customers (like those with a few items) are served first.

7. Scheduling

Scheduling determines when and how packets are transmitted over the network. It involves assigning transmission times to different queues based on their priority.

For example, a network might schedule VoIP packets to be transmitted during periods of low network congestion to ensure high-quality voice calls.

Think of Scheduling as a teacher organizing a class schedule. By assigning specific times for different activities, the teacher ensures that all subjects are covered efficiently.

By mastering these Traffic Shaping and QoS concepts, you will be well-equipped to manage network traffic effectively, ensuring optimal performance and reliability for critical applications.