In Queueing theory, we create a model of the Queuing system so that we can predict the performance of the system for parameters like: Typically, a Queue is formed when people arrive at a place to get some kind of service like getting coffee, grocery, medical help etc. We see Queues every day in our life, whether it’s a line in Starbucks, queues of vehicles on the road, packets in Data networks, Grocery line etc. Queuing theory is basically the mathematical study of waiting lines. Then we will look at the simple Queueing model, derivation and then see how we can use that to calculate the Average Network delay. In order to understand more about Queueing delay, we have to take a step back and look at the basics of Queuing theory first. If the Queue is empty, then it transmitted immediately, but if it’s sitting behind other packets, then it needs to wait for the packets in front to be transmitted first (common sense). The amount of time it needs to wait depends on the size of the Queue.
Queuing delayis the time spent by the packet sitting in a queue waiting to be transmitted onto the link. Total Delay = Processing Delay + Transmission Delay + Propagation Delay + Queuing Delay Out of the Four factors, queuing delay is the one which is most interesting and most complicated. There are typically four factors which contribute to a packet delay in a network. My as usual disclaimer, that I am going to take some luxuries while explaining to keep things simple, so it’s possible that some statements may not be mathematically accurate.Please be aware that whatever we cover here only allows us to measure the first order approximation of what happens in real life and it is good for use cases like topology design but not for measuring the exact state of a network for operational purposes.What we are going to look at is the most basic form. This post will involve Queuing theory and the Math involved in Queuing theory gets complicated very fast, especially for an average guy like me.There is no way I can do the justice in explaining all the basics without distracting from the main goal of the blog post. A background in Probability theory, particularly familiarity with Poisson and Exponential distribution will help.Which got me thinking that for topology design related problems, how can I calculate the Average network delay? As you can guess, This blog post is all about this.īefore starting few things to keep in mind: So recently I was looking at the Linear programming formulations of Traffic engineering problems and one of the problem was to find the path with the goal to minimize the Average network delay.
0 kommentar(er)
