ネットワークおよびアプリケーションの根本原因の解析|フルーク・ネットワークス


 

Network and Application Root Cause Analysis - Part 1 by Chris Greer

For many people, tracking down root cause of a network or application problem involves late nights with several analysts pouring over screens of data, all taking different routes to the same conclusion - or in some cases, no conclusion. In a word, these situations can be described as: Intimidating.

How can we pull the intimidation out of root cause isolation?

It sounds cliche, but the best way to isolate root cause is to keep it simple! Only so many things can impact the performance of a network or application, and eliminating them one at a time isn't too difficult. All we need is the right visibility.

In this article, we will talk about isolating root cause on network performance problems. Next time, we will tackle application performance issues.

Network Performance is generally impacted by these three things:

  1. Packet Loss
  2. Capacity Problems
  3. Wireless Network Problems

It used to be that the top two were the heaviest contributors to poor network performance, but with the BYOD phenomenon and the increase in wirelessly connected devices, the WiFi environment can now be listed as a pain point.

  1. Packet Loss - If the network is slow, the first thing to do is to comb the network path from client to server, looking for errors that cause packet loss. The simplest way of doing this is using the Graphical Path Analysis in the OptiView XG. Not only does it show the network path, but it also displays network capacity and errors for every interface along the way.
  2. Capacity Problems - These are typically not experienced on 10Gig or even 1Gig links. Often these are found on lower-capacity router connections between buildings or on data center connections. The best way to monitor for capacity problems is by using a flow-based tool such as NetFlow Tracker. Problems with utilization can be analyzed, even if they occurred in the past.
  3. Wireless Network Problem - There is a whole lot to consider when wireless access is slow. Breaking it down, these are most often caused by interference - whether from competing channels or non-802.11 devices - and client overuse. For example, if a wireless user decides to watch a video or stream a radio feed, this will dramatically impact performance for the other users. A great tool for tracking down these issues is the AirMagnet Analyzer, available on the OptiView XG or as a stand-alone product. There is no need to be an RF expert. The AirMagnet Analyzer automatically points out performance killers and gives suggestions on resolving them.

We will do deeper into each of these causes of slow network performance in the future. But for now, isolating a problem to one of these three is the fastest way to resolve network problems.

Next up - top three causes of slow Application Performance.

Related IT Networking Resources
Challenges of the Traditional Approach to Management
Data Center Project Best Practices #1: Assessment
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