Category Archives: Troubleshooting

How To Forecast Network Bandwidth Needs Using Cisco® NetFlow

It starts with users complaining that “the network is slow”.  As a network admin, we keep hearing this same feedback no matter how much the bandwidth is upgraded or QoS policies are implemented. It is hard to find a way to predict bandwidth consumption unless you analyze how it is consumed. NetFlow traffic data will help you answer when, by whom (users), and by what (applications and endpoints) network bandwidth is being utilized.

NetFlow, a network protocol developed by Cisco for collecting IP traffic information which eventually became the universally accepted standard on traffic monitoring, is included on most network routers and switches. With NetFlow you will be able to get visibility into real-time network bandwidth utilization, analyze historical and current traffic trends, and forecast whether there is any actual need of more bandwidth or you can optimize usage and save procurement budget.

Capacity Planning for your Future Needs

There are two primary reasons you want the ability to forecast bandwidth capacity needs: maintaining or improving network performance in order to ensure critical IT services, and managing the cost of bandwidth. By analyzing bandwidth consumption using NetFlow data you will be armed with measurable data to help you make bandwidth decisions, which in turn eases the capacity planning process. For instance, if you have unwanted traffic consuming most of the network, you wouldn’t have enough bandwidth for critical IT services like VoIP calls. By analyzing NetFlow, you’ll understand the type of applications that are consuming most of your bandwidth.

QoS policies for Managing Critical IT Services

Applications compete with each other for bandwidth when traversing the LAN/WAN and since bandwidth is neither infinite nor free, you will want to see how your bandwidth is being used.  Network traffic monitoring flow analysis tools help differentiate the types of network traffic by reporting on Type of Service (ToS) and DSCP fields from traffic conversations so you can monitor your bandwidth usage by application and measure the effectiveness of your QoS policies.

Historical data on NetFlow helps Capacity Planning

When you collect historical NetFlow data on your network, you can understand when bandwidth peaks happen in a day and how your users’ performance is impacted. Granular (i.e. one minute) visibility and long data retention will allow you to see past traffic spikes in order to better understand potential bottlenecks.

Better Forecasting Increases Productivity

Detailed NetFlow data collection can solve most of your puzzle in capacity planning. It helps plan network capacity more accurately—by deploying greater bandwidth for advanced networking services—as you scale up. Leveraging NetFlow, one can easily check if bandwidth growth is aligned with resources utilized in the current environment and plan for the future.

Using a NetFlow analyzer tool, you can capture raw NetFlow data, convert it into meaningful information that can give you real-time network traffic information, and perform capacity planning. Scaling your bandwidth based on network requirements and implementing QoS policies becomes much easier if you have relevant network traffic information.

Here are some additional resources for learning more about NetFlow and its applications:

Whitepaper:  NetFlow Tips and Tricks

Online Interactive Demo:  NetFlow Traffic Analyzer

Trial Download:  SolarWinds Bandwidth Analyzer Pack

About the Author:

Brad Hale, Product Marketing Principal for SolarWinds Network Management

Brad Hale is the product marketing principal for SolarWinds network management products.  He brings over 20 years of product management, product marketing, business development and strategy experience in the software, systems and semiconductor industries.  Brad has a BS in Computer Engineering from Purdue University and an MBA from Butler University.

David’s Top Cisco Tips of 2008

TechRepublic published the following list of my Top 5 Cisco Tips of 2008. As these were very popular with readers, they must have some value, right? Seriously, I hope you will check them out:

1. Practice Cisco router configuration using a free emulator
David Davis explains how a free emulator can benefit your router administration. The ability to run multiple routers inside your PC is very useful for testing and training. It can save you the time and trouble from having to invest in a test Cisco network, and it certainly makes it more convenient.

2. Five things you should know about configuring a Cisco IOS switch
David answers some of the most frequently asked questions about switch configuration and explores some of the basics.

3. Is pt360 the all-in-one Cisco tool we’ve been looking for?
David loves finding new tools that help manage and troubleshoot routers. But what if you had to choose just one network management and troubleshooting tool? Do you think there’s one tool out there that’s really “best of breed”? Here’s one candidate.

4. 10 dumb things you can do to your Cisco router and how to fix them
David points out the dumb things you can do to mess up your Cisco router and how to fix them. He also lists some important resources for each step to give you even more detailed instructions.

5. Use extended ping and extended traceroute to better troubleshoot your Cisco network
Every admin is familiar with the well-known troubleshooting commands ping and traceroute. David shows you how to use these commands in their extended versions to become an expert at troubleshooting your Cisco network.

Cisco Photo Galleries

PacketTrap PerspectivePacketTrap Perspective provides network management tools for Cisco
David Davis walks you through PacketTrap’s new network management platform, Perspective.


Cisco 851WConfiguring the Cisco 851W or 871W: Standard IOS
The Cisco 851W router is a relatively low cost multipurpose device, which can support virtual wireless LANs separated by firewalls.

Understand the OSI model to become a better Cisco troubleshooter

While the OSI Model may seen like some useless & arcane topic that you only study to get your CCNA, I believe it is very valuable in understanding how networks work and how to troubleshoot them. In one of my most recent articles, I cover the OSI model and explain how you can use it to better troubleshoot your Cisco network.

To read the full article, visit:  Understand the OSI model to become a better Cisco troubleshooter