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JA3. Traffic Shaping and Traffic Policing

Statement

Reflecting on the reading resources and your own research, respond/complete the task mentioned in the following scenario:

  • As a network engineer, you have been hired by XYZ Company to implement Quality of Service (QoS) on their enterprise network in order to improve the quality of their network.
  • You are considering using one of the major QoS techniques - scheduling or traffic policing - or a combination of both.
  • In order to come to a conclusion, your supervisor has tasked you to list the pros and cons of traffic shaping and traffic policing QoS techniques.

Answer

Quality of Service (QoS) is a set of techniques that are used to ensure minimum requirements of performance through a network; these techniques utilize traffic engineering and Software-defined networking (SDN) to ensure parameters like bandwidth, latency, jitter, and packet loss are met (Huawei, 2022).

Serval traffic engineering techniques are used to implement QoS (Fulber-Garcia, 2022):

  • Shaping: A link would enqueue traffic that exceeds the configured parameters, and then transmit it later according to the state of the network downstream.
  • Policing: A link would immediately drop traffic that exceeds the configured parameters.
  • Scheduling: A link would prioritize traffic based on the configured parameters and the state downstream; multiple queues are used with each having a specific rate of rebasing packets.
  • Washing: A link would partially drop some packets that may be not important to the extent that it does not affect the service but reduces the load on the network.

A healthy network would include a combination of all these techniques as each of them serves a specific purpose, but combining them together ensures a smooth and efficient networking experience.

The pros of traffic shaping and policing include (Mishra, 2022):

  • Both Ensure that the traffic is smooth and does not exceed the configured parameters
  • Both Ensure that the load passing through the network is within the network’s capacity.
  • Policing allows networking providers to provide flexible charging models, E.g. X GB of data per month, as it can immediately drop all traffic exceeding the limit.
  • Policing can help with security as it can drop suspicious traffic immediately.
  • Shaping can help with load balancing across all network links, as it can send traffic away from busy links to less busy links.
  • Both help in managing and avoiding network congestion.

The cons of traffic shaping and policing include (ExtremeNetworks, 2022):

  • Both can introduce latency in the network, as they need to make decisions and read diagnostics before taking action; but this latency is within the acceptable range if prioritized correctly.
  • Both require complex configurations and management, which means extra training and maintenance costs.
  • Both may require changing traditional hardware to support these features, which can be expensive.
  • Shaping may cause starvation or packet loss if not configured correctly.
  • Policing may cause important traffic to be dropped.

To conclude, network engineers should use a combination of traffic shaping and policing; the balance between the two depends on the context. For example, in a general-purpose network, shaping is important as different services and protocols have different requirements where some delay/loss is acceptable and others are not; it is a key feature to allow all types of traffic to run smoothly. Another example; is building a network with a focus on security or serving an ISP, where policing is important as it can immediately drop suspicious traffic and enforce charging models.

References