Policing vs. Traffic Shaping

Attribute	Policing	Traffic Shaping
Definition	Enforcement of predefined rules to control network traffic	Regulating network traffic to meet specific criteria or policies
Objective	Prevent network congestion and ensure fair resource allocation	Manage bandwidth usage and prioritize certain types of traffic
Implementation	Usually done at network ingress points	Can be implemented at various network points
Enforcement	Strict enforcement of traffic limits	Flexible enforcement with adjustable parameters
Packet Handling	Excess packets are dropped or marked	Excess packets are delayed or queued
Granularity	Usually operates on a per-flow basis	Can operate on a per-flow or per-interface basis
Impact on Latency	May introduce latency due to dropped packets	May introduce latency due to packet buffering
Usage	Commonly used in Quality of Service (QoS) implementations	Commonly used in bandwidth management and shaping

Introduction

When it comes to managing network traffic, two commonly used techniques are policing and traffic shaping. Both methods aim to control the flow of data within a network, but they differ in their approach and the outcomes they achieve. In this article, we will explore the attributes of policing and traffic shaping, highlighting their similarities and differences, and discussing their respective advantages and disadvantages.

Policing

Policing is a technique used to enforce traffic policies by monitoring and controlling the rate of data transmission. It involves examining packets of data and determining whether they comply with predefined rules or thresholds. If a packet violates these rules, it can be dropped or marked for further action. Policing is typically implemented at network ingress points, such as routers or firewalls, where it can inspect incoming traffic and enforce policies.

One of the key attributes of policing is its ability to enforce strict limits on data transmission rates. By dropping or marking packets that exceed the defined thresholds, policing helps prevent network congestion and ensures fair allocation of bandwidth among users. This attribute is particularly useful in scenarios where network resources are limited, and it is crucial to prioritize certain types of traffic, such as real-time applications or critical services.

Another advantage of policing is its simplicity and efficiency. Since it primarily focuses on monitoring and controlling traffic based on predefined rules, it requires less computational overhead compared to other techniques. Policing can be implemented using simple algorithms, making it a cost-effective solution for managing network traffic.

However, policing also has its limitations. One of the main drawbacks is its inability to shape or modify traffic patterns. Policing can only drop or mark packets that violate the predefined rules, but it cannot alter the behavior of traffic flows. This means that even if a packet is marked, it will still be transmitted at its original rate, potentially leading to bursty traffic patterns and inefficient resource utilization.

Furthermore, policing can be seen as a more reactive approach to traffic management. It focuses on identifying and penalizing non-compliant traffic, rather than actively shaping the traffic to adhere to predefined policies. This reactive nature may result in occasional congestion or delays, especially during periods of high network utilization.

Traffic Shaping

Traffic shaping, on the other hand, is a proactive technique that aims to control the flow of data by modifying the shape of traffic patterns. Unlike policing, which drops or marks packets, traffic shaping buffers and delays packets to smooth out the traffic flow and ensure compliance with predefined policies. It is typically implemented at network egress points, such as routers or switches, where it can control the rate at which packets are transmitted.

One of the key attributes of traffic shaping is its ability to shape traffic patterns according to predefined policies. By buffering and delaying packets, traffic shaping can regulate the flow of data and ensure a more consistent transmission rate. This attribute is particularly useful in scenarios where it is important to maintain a steady flow of traffic, such as video streaming or voice over IP (VoIP) applications.

Another advantage of traffic shaping is its ability to prioritize certain types of traffic over others. By assigning different levels of priority to packets, traffic shaping can ensure that critical or time-sensitive data is transmitted with minimal delay, while less important traffic is given lower priority. This attribute is crucial in environments where quality of service (QoS) requirements need to be met, such as in enterprise networks or service provider networks.

However, traffic shaping also has its limitations. One of the main drawbacks is its potential to introduce additional latency. By buffering and delaying packets, traffic shaping can increase the overall delay experienced by network traffic. This latency can be problematic for real-time applications that require low latency, such as online gaming or video conferencing.

Furthermore, traffic shaping can be more complex to implement compared to policing. It requires the use of sophisticated algorithms and mechanisms to buffer and delay packets effectively. This complexity can result in higher computational overhead and increased costs associated with deploying and managing traffic shaping solutions.

Conclusion

In conclusion, policing and traffic shaping are two distinct techniques used for managing network traffic. Policing focuses on enforcing traffic policies by dropping or marking non-compliant packets, while traffic shaping proactively modifies traffic patterns by buffering and delaying packets. Both methods have their advantages and disadvantages, and the choice between them depends on the specific requirements and constraints of the network environment.

Policing is a simpler and more efficient approach that can enforce strict limits on data transmission rates, making it suitable for scenarios with limited network resources. However, it lacks the ability to shape traffic patterns and can be seen as a reactive approach to traffic management.

Traffic shaping, on the other hand, offers the ability to shape traffic according to predefined policies and prioritize certain types of traffic. It is particularly useful in scenarios where maintaining a steady flow of traffic or meeting QoS requirements is crucial. However, it can introduce additional latency and requires more complex implementation.

Ultimately, the choice between policing and traffic shaping depends on the specific needs and goals of the network. By understanding the attributes and trade-offs of each technique, network administrators can make informed decisions to optimize their network performance and ensure efficient utilization of resources.