Why You Need NetFlow: See Who Is Using Your Bandwidth and Why

Posted on November 30, 2011 by Petri IT Knowledgebase Team in Cisco with 0 Comments

NetFlow is a technology developed by Cisco that allows you to collect IP traffic information so you can monitor your traffic and see who is using your bandwidth and why. It is a powerful and extremely useful tool for network monitoring and something every network administrator should know how to use.

In this video from Josh Stephens, Head Geek at SolarWinds, you’ll learn more about NetFlow and why you need it. Josh will also share some information on how to use NetFlow with a couple of free and paid tools from SolarWinds.

Following is a full transcript of the interview.

Josh Stephens: Howdy, y’all. Josh Stephens here, Head Geek at SolarWinds, and today we’re going to talk for a few minutes about NetFlow. Now, NetFlow is a technology that you not only should know about, you really need to know about it as a network engineer. NetFlow is a technology that actually turns your routers and switchers into traffic analyzers.


Now, a few years ago, there were a lot of us that tried NetFlow but saw that it had a negative impact upon our routers and switchers. And the software available for consuming NetFlow and helping us actually use it were expensive and hard to use.

Today that’s not the case. NetFlow technology has come a long way and the routers and switchers out in the industry available today can actually do traffic analysis and can pass traffic and do their normal jobs without a problem at all.

Why You Need NetFlow

Josh Stephens: So, I’m going to talk to you a little bit about why you need a NetFlow. NetFlow is the kind of thing that, as a network engineer, it’s become a core part of what you do every day, being able to understand who’s using your bandwidth and why.

In the old days, it was enough to know how much bandwidth was being used on our networks and our Internet connections. But nowadays, it’s not enough because they’re almost always fully consumed. So now you need to really be able to analyze the traffic, to understand the applications, how they’re running across the network, who’s using that bandwidth, what they’re doing with it, how any QoS changes you’ve made have impacted application performance. And NetFlow is a really neat technology to help you do that.

Something else to keep in mind about NetFlow is, it’s fairly easy to turn on in terms of configuring the routers and switchers, and also in terms of configuring the device, or the system, to listen. Now, here at SolarWinds, we’ve made it actually a lot easier. So I’m going to walk through how you might get started using NetFlow.

How To Use NetFlow

Josh Stephens: The first thing I would do if I wanted to use a technology like NetFlow is, I’d go join a community like Thwack.com; Thwack is our online community here at SolarWinds. It’s a really good place to go and learn about technology like NetFlow, like traffic analysis, really, really a neat place to go, learning from other network engineers that are doing similar things to you and that might know more about the subject.

Now, once you’ve done that, you might need some cool tools to help you. Here at SolarWinds, we actually offer a starter kit to help you get going with NetFlow really, really quickly.

The first thing I’m going to show you is actually a free tool from SolarWinds called the NetFlow Configurator. All you have to do to NetFlow Configurator is give it the IP address and community string of your router or switch, and it will let you dynamically configure which interfaces you want to export traffic from and analyze for traffic using NetFlow. Just simply that simple, and you’re done. Very, very easy to use and free.


I also want to talk about the new, Real Time NetFlow Traffic Analyzer from SolarWinds. This is also a free application that you can download from SolarWinds.com, and lets you analyze the traffic on your network, using that NetFlow technology that you’ve already paid for within your routers and switchers. So it’s really completely free.

Now, it lets you see which applications are on the network. It will let you see, for instance… I see here our developers are playing World of Warcraft again. I can see which users are doing it, what conversations, what applications and protocols are on the network. Very, very, easy to use… One of my favorite applications to use for when I’m troubleshooting networks and when I need to find out why the network is slow.

Now, obviously, if you have a need for a more scalable solution, we’d like you to take a look at Orion. Orion’s NetFlow Traffic Analyzer is an enterprise class application, can receive flows from thousands of devices at once, and keeps that data for a very long time for analysis.

So again, Josh Stephens here at SolarWinds, Head Geek. And keep in mind, NetFlow is a technology you should really learn and use as a network engineer. Thanks.