Thursday 12 July 2012

Traffic shaping

Traffic shaping (also known as "packet shaping") is a computer network traffic management technique which delays some or all datagrams to bring them into compliance with a desired traffic profile. Traffic shaping is a form of rate limiting.

Traffic shaping is used to optimize or guarantee performance, improve latency, and/or increase usable bandwidth for some kinds of packets by delaying other kinds of packets that meet certain criteria. If a link becomes saturated to the point where there is a significant level of contention (either upstream or downstream) latency can rise substantially. As a result, traffic shaping can be used to prevent this from occurring and keep latency in check. Traffic shaping provides a means to control the volume of traffic being sent into a network in a specified period (bandwidth throttling), or the maximum rate at which the traffic is sent (rate limiting), or more complex criteria such as GCRA. This control can be accomplished in many ways and for many reasons; however traffic shaping is always achieved by delaying packets.

Traffic shaping is commonly applied at the network edges to control traffic entering the network, but can also be applied by the traffic source (for example, computer or network card) or by an element in the network. Traffic policing is the distinct but related practice of packet dropping and packet marking. The technique of selecting or categorising traffic into different types or classes is traffic classification.