Thoughts on CWNP's Certified Wireless Design Professional (CWDP-302).
The CWDP validates your knowledge of designing wireless networks where you need a pretty good understanding of spectrum, protocols used, security implementation, site surveys – including predictive, manual, hybrid, and validation.
An important part of CWDP, and also in the real world, is being able to gather requirements from the end user. Knowing what the end users need to do on Wi-Fi will help you build a successful network.
Some of the aspects of gathering requirements are straight forward, such as finding out where coverage is needed, what applications are going to be used, is VoIP going to be used, etc.
Knowing what type of devices are going to be used is also important. This plays a role into capacity planning with the applications that will be used. Other areas to consider are designs around regulatory requirements.
This part of the exam takes up 20% so take a look at the objectives. You'll need to know how these requirements impact the design of a WLAN.
Design takes up 40% of the exam. In this area, experience really gives you a big advantage. Knowing the different architectures such as distributed forwarding and tunnel-based of client data traffic. How someone should design between single channel architecture and multiple channel architecture is something to consider. Although the most important thing is knowing the difference between the two.
Different PHYs will have different capabilities, such as designing for 20 MHz to 160 MHz channel widths. Know what the gotchas are with client devices when designing for a PHY such as 802.11ac.
When it comes to roaming, know the different kinds of roaming technologies and when they would be used. Do you know the difference between opportunistic key caching and PMK caching? Depending on client requirements, this may be important given that some of these roaming methods play a role with latency.
You can’t talk about designing without mentioning site surveys. There are different kinds of site surveys that a designer should be familiar with.
Performing site surveys will make a lot of sense in the CWDP exam. Many of the terms mentioned in these objectives will come easier to you during studies. Metrics such as SNR, signal strength, CCI, data rates, etc. All metrics you can get in a predictive or validation survey.
WLAN Deployment only takes up 5% of the exam but its important to understand that there is more to access points and controllers in design. Consider the infrastructure side such as DHCP and DNS servers. You should also be familiar with how access points are installed with varying types of architectures.
Design validation takes up 15% of the exam. In the real world this is very important. This includes doing a post-installation site survey to validate the WLAN met the requirements gathered in the Requirements Analysis objective.
Be familiar with the tools used in this step which include the validation software, protocol analyzer, and spectrum analyzer. Some other tools that may be used are throughput testers as well to verify capacity.
These tools should also help troubleshoot issues that may involve roaming and QoS.
Overall, the CWDP exam came natural to me. I do quite a bit of designing in my role. It took me about 30 days to study for this exam using the CWDP-302 official study guide.
Studying was faster for me because of the tools I was already familiar with and the procedures involved with design.
The official study guide didn’t include any chapter quizzes which I found disappointing. I didn’t get a chance to gauge my progress. But while reviewing the objectives I felt very confident. In the end, I passed the CWDP exam with a great score.
I do recommend purchasing the previous CWDP text book, the Sybex PW0-250 for in-depth knowledge. The new book in comparison is much thinner.
So during my studies I did have both textbooks but for the exam I relied on the one for CWDP-302.
With 7 chapters in the book, it’s possible to read one chapter a week and aim for sitting the exam in 8-9 weeks if you have experience.
Unfortunately, I cannot speak to any of them since I didn’t take any of their courses. I also cannot speak to the practice exams, but I like to use CWNP’s practice exams as much as possible.
So those were my thoughts on the CWDP exam. I found this one to be less challenging than the other CWNP exams. My work in designing WLANs may have had an impact. That’s the reason why I have no published a new episode in a while. I spent a lot of time studying for CWDP and for the CWSP, which I’ll talk about in a future episode.