It can be so easy to be mislead by vendors claiming incredible bandwidth gains offered by their new ’3 Spatial Streams’ wireless access points. The tricky part is that none of them are outright lying, they are simply describing a reality that nobody lives in. Cisco released the new 3600 series access points at CiscoLive London last week. We have also had fun showing the incredible bandwidth gains available through this extra stream -- but we did it with custom designed silicon to create a 4x4 radio. Why is this valuable to you? Is it not just ‘more is better?’ Hardly. The true genius being offered here is only clear when you understand some basics of how radios work. Multiple capabilities unique to Cisco come into play here such as ClientLink and CleanAir. Watch this ‘Fundamentals of Spatial Streams’ to arm yourself with knowledge you can apply right away. It will be the best 6 minutes of your life (today at least).
CleanAir continues to provide significant differentiation for Cisco Wireless as well it should. What many don’t realize, is how much of the attractive visualization and control is not from CleanAir itself, but CleanAir plus the Mobility Services Engine. I would go as far as to say there are several very important distinctions for why the MSE should be considered a mandatory element within any Cisco Wireless Design.
Lately I had been spending a lot of time in the office rather than on the road. Which isn’t all bad, as it gives me some semblance of a routine rather than living out of a suitcase. It has also has given me some spare time to come up with another blog topic, which actually stems from some of the work I have been doing for customers lately.
Typically when a site survey is being done, we will do spectrum analysis work as well, part of my job entails creating and reviewing documents from this work, prior to delivering them to customers, which means I have been watching a lot of spectrum analysis lately. Most of the customers I have worked with recently have been with CleanAir APs, so they will be able to monitor their environment in real time, once the WLAN is up and running. However it’s always a good idea to perform some spectral analysis while you are walking around doing a site survey. And really why not? If you are there and you have a few minutes, fire up the old spectrum card and get a capture of whats going on with your RF. This helps make sure there aren’t any major layer 1 surprises when you go to install the new WLAN. It doesn’t mean things won’t change, and they often will, due to the dynamic nature of RF. It’s an ever changing environment, so what wasn’t there on Monday, might show up on Tuesday and be gone again by Wednesday.
Before jumping into particular types of interferes let’s talk about some of the data that Cisco Spectrum Expert can show you. Two of the things I like to look at when looking at the RF in Cisco Spectrum Expert, are Real Time FFT and Duty Cycle plots, as pictured below.
The Real Time FFT is showing you is the RF energy in real time measured in dBm, so how loud or quiet the device is. The next is the FFT Duty Cycle, which simply put it’s how utilized the RF is. Let’s say you have a device that is being captured as having a 1% duty cycle. This means it’s using a very small amount of the available ‘air time’ to transmit its data. Conversly if there is a device that is showing a 100% duty cycle it is using up all the ‘air time’ and not allowing other devices to use the RF medium to transmit.
Two other views I find helpful are the Spectrogram views. These display the same info as the plots above, but are plotted out over time. I use them in a few of the examples below.
Inclusion in some government lists may not be such a good thing… for example, the government “no fly list” could be a bummer as you board your flight on your next family vacation. Yet, other government lists can make or break you when it comes to doing business with the Federal Government. Last week, the award winning Cisco CleanAir technology was placed on the all important DoD Unified Capabilities APPROVED PRODUCT LIST (DoD UC/APL). The DoD APL happens to be the official product list that DoD agencies are required to work from when making new acquisitions for network equipment such as routers, switches, WLAN, voice, video etc. With the latest Cisco DoD APL certification, the Cisco CleanAir 3500 Series Access Point becomes the first DoD approved product that supports “built-in” system level spectrum intelligence in support of mission critical wireless networks.
In some ways, the DoD APL is like an exclusive club for a select group of IT vendors –either you are a club member or you stand outside the gate. The process to get products listed on the APL is no cakewalk. First, even before products can be considered for the APL process, the products must meet a series of stringent DoD requirements and certifications such as DISA STIGS, FIPS & Common Criteria. Next, a DoD sponsor must agree to represent the vendor’s products throughout the APL certification process. The actual certification process itself involves several months of rigorous interoperability and Information Assurance compliance testing.