Posts Tagged ‘statistics’

PowerShell: Query Cisco (Catalyst 4500) Flow Control statistics

Written by Ingmar Verheij on June 1st, 2012. Posted in PowerShell

Last week I attended E2EVC in Vienna, a non-commercial,virtualization community Event, and attended a session of Saša Mašić about an issue he had at a customer. In short, the problems where caused by a switch that couldn’t process IP packets because it overflowed, and therefore Ethernet flow control temporarily stopped the transmission of some attached devices. Although I’m no network expert I do know this might be a serious issue. After reading this article, you might agree.

If you’re looking for the PowerShell script, scroll to the bottom.

RxPause and TxPause

This week I  was asked to troubleshoot performance issues at a customer and got informed that the core switches (Cisco Catalyst 4500) might be over capacity. A quick look in the flow control statistics (# show flowcontrol) indicated there where send numerous RxPause and TxPause packages, a sign Flow Control has been active.

Average : Mean versus Median

Written by Ingmar Verheij on July 5th, 2011. Posted in Performance testing

I love being averageThe average of a set of numbers is a commonly used, but the defintion of average is poorly understood and can raise the risk of being manipulated.

The average of a set of numbers can be determined with the mean or the median. To better understand the difference between mean and median I will explain the definition of both and illustrate it with examples.