TRAFFIC SHAPING

Traffic Shaping

Traffic Shaping

Introduction

Traffic shaping is a strategy to optimize performance and manage traffic on a network. Because most networks have a limited amount of bandwidth? an effective strategy is needed to ensure the network does not become overloaded. Computer network traffic can sometimes cause a network to become so busy is leads to choking points. To understand traffic shaping it is first important to understand how information is transported through a network. Information is sent over networks in packets? which are nothing more than formatted blocks of data. These data packets may be given different priority levels as they go through a network in order to optimize performance. This is at the heart of the traffic shaping model (Argyris? 1991? 102-113).

In some ways? it is not much different than vehicle traffic on a street? which is a form of traffic shaping in the physical world. In general? street traffic is all considered to have the same priority level? no matter what individual drivers may think. However? some cars — or packets in networking terms — are delayed by stoplights so as not to create a bottleneck at certain points. Eventually? these cars will be allowed to proceed. In some cases? an emergency vehicle may be going on a call? thus all the normal vehicles will be delayed as the emergency vehicle is given priority (Argyris? 1991? 102-113).

In network traffic shaping? packets can be prioritized in different ways. Some may be prioritized based on the information being sent. Others may be prioritized based on the computer sending the information or the computer receiving the information. In addition? if many users compete for the same bandwidth? traffic shaping can be used as a way to ensure everyone receives the same priority. If a computer is using the network heavily? then the packets from that computer could be delayed so that others are given fair and equal access.

Internet service providers can also use traffic shaping as a means of controlling traffic on their own networks. There are certain Internet applications that demand low latency in order to get the maximum effect (Booth? 1996? 52-61). Low latency is another term meaning fewer delays. Packet shaping can help voice applications and online gaming experiences? for example? achieve their maximum effectiveness by delaying some other packets. While traffic shaping does cause some concerns among some computer users? the overall goal is to make a network run as smoothly as possible. This may take a good network engineer setting the rules in order for that to be achieved. Just like with bad vehicle traffic patterns? network traffic shaping done incorrectly can cause more problems than it intends to solve.

Policing Versus Shaping

The following diagram illustrates the key difference. Traffic policing propagates bursts. When the traffic rate reaches the configured maximum rate? excess traffic is dropped (or remarked). The result is an output rate that appears as a saw-tooth with crests and troughs. In contrast to policing? traffic shaping retains excess packets in a queue and then schedules the ...