Cisco Blogs

Your Network’s Worst Enemy

September 17, 2007 - 8 Comments

Wireless networks have matured to the point where security is no longer their primary concern. More and more I am hearing from customers that their primary issue these days is interference.Interference is one of those things that is really tricky to both identify and resolve. There are few IT geeks out there that I’ve met, who happen to understand networking and the complexity of radio frequencies. In fact, I wouldn’t be surprised if most people reading this blog entry have never even seen a spectrum analyzer. I know I have, but it has to be a very bad day when I need to turn one on… It is in fact for this main reason that as we designed the unified Wireless LAN controller – to take the science out of RF and try to provide more visibility in a manner that most networking experts understand. We turned that complex spectrum analyzer into a graph that would show the health of the network, by showing both interference (other 802.11 traffic) and noise (non 802.11 traffic). We’ve heard consistently from our customers how much they appreciate getting a better understanding of their network.The past year has been a very exciting time for us in the Wireless LAN business, as we’ve seen the technology grow from a convenience to a mission critical network. Ironically, while I think we all agree of the importance of this network, most IT managers would still prefer to treat it as a secondary network – and I believe that this is mostly because the science behind RF makes it a very difficult network to troubleshoot. What does one do when excessive noise shows up? It’s not quite like calling your neighbor and asking them to turn down the Deep Purple they’ve been blasting since 9PM (ok… I’m showing my age… these days you’d probably be complaining about Linkin Park). The expertize, and equipment, required to identify the source of noise is so complex that most people simply leave it alone – but this is becoming more of a problem as more of these devices are introduced in your network, while your users expectations of the network increases. As we were designing the WLAN unified system, we quickly came to the conclusion that trying to identify the source of “noise” would be nearly impossible for most customers, and this was in fact the impetus for creating our Radio Resource Management (RRM) system. RRM is a set of algorithms that are run to optimize the configuration of the various radio parameters to increase the system’s performance (for those that are interested, I will write a piece of RRM in a future blog). RRM certainly solved many of the issues in our customer’s networks, by reconfiguring the network to move away from a source that is harming the performance of the network. Ultimately, we need to start thinking about how we can provide more visibility into what is causing the noise – and remove these interferers to help regain some sanity in our air space.

In an effort to keep conversations fresh, Cisco Blogs closes comments after 60 days. Please visit the Cisco Blogs hub page for the latest content.


  1. Actually, the Cognio offering is very unique in the market, and represents multiple years of engineering development and a strong team that understands the challenges of interference (and how to detect it). Building technology in-house is something we do on a daily basis at Cisco, as evidenced by the broad feature-rich portfolio of wireless products. In this case, the complexity and development time/cost of the technology, along with strong customer feedback received during the due diligence process, made the acquisition the right choice.

  2. Pat,Not so unique from what I hear. I do remember that Cisco did try to develop its own WLAN switch architecture and competed a few years ago. So, WNBU does not have the guns today to at least give it an old college try against a teeny company out of Germantown, Md.? Hmmm....We wanna know!

  3. Cognio has developed a unique ASIC-based technology. The technology we acquired is consistent with Cisco's vision and direction, and it greatly enhances our ability to manage interference.Cisco's acquisition process is quite sophisticated, and we do balance internal development, cost and complexity of solutions, market needs and time to market. After significant due diligence, Cisco agreed the acquisition was the proper approach.Unfortunately, I cannot disclose additional details on the acquisition than what has already been made public.

  4. So, they are better than you are? Yes or No? Why not just delay the market and compete with them? Or is there something else that is forcing your hand? Also, what is the price of this acquisition?

  5. Azul,Providing spectrum management, as Cognio does, with complete visibility into signal patterns is actually very complex and requires very specialized hardware. You are correct that Cisco has the best RF engineers in the business, but we felt our customers would benefit from the time to market advantages of this best of breed solution.

  6. Why not develop this tool in-house? Seems very trivial task for a company with 300 engineers and great RF expertise. The money to develop this type of product is far less than the expenditures to acquire the assets of of another company. is not a sound business practice."

  7. No argument there. A spectrum analyzer clearly provides a significant amount of information that the Unified WLAN controller cannot through its noise and interference graphs. However, it has been very useful for both troubleshooting and Radio Management purposes.That said, you raise a great point that users really need more visibility into their air space. Ideally, one needs to identify the noise source, and the patterns emitted, in order to better understand how it will interfere with the network. Well, I am happy to announce that Cisco will be providing this capability through the Cognio acquisition, which was announced today. More details on the acquisition can be found at: Cognio acquisition allows Cisco to fulfill its vision to provide the tools necessary for our customers to be able to treat their wireless network as mission critical. The Cognio technology is capable of taking the complex output of an integrated spectrum analyzer, and provide a report that is both comprehensive and simple to understand - all integrated into a single wireless management tool.Is there something that is jamming your 2.4Ghz spectrum all of a sudden? Well... with this new technology we will be able to tell you about that new wireless video camera that one of your users installed to finally catch the person that's been stealing his chocolate chip cookies."

  8. Pat,There are many more things that a spectrum analyzer gives a technician that a simple bar representation of RF spectrum does not.