Clear To Send: Wireless Network Engineering

By Rowell Dionicio and François Vergès

Clear To Send is a podcast about wireless engineering where we educate you on WiFi technology, talk about design tips, troubleshooting, interviews, and the tools.... more

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FAQs about Clear To Send: Wireless Network Engineering:

How many episodes does Clear To Send: Wireless Network Engineering have?

The podcast currently has 467 episodes available.

Clear To Send: Wireless Network Engineering episodes:

October 31, 2016 CTS 054: 4 Scary Things Lurking in Your Wi-Fi
In the spirit of Halloween I wanted to go into a theme of scare and fright. While these may not make the hair on your neck stand, I don’t know maybe they do, these issues can lead to managing a scary wireless network. Scary because of end user complaints and because these can be running […]
The post CTS 054: 4 Scary Things Lurking in Your Wi-Fi appeared first on Clear To Send.
...more
16min
October 31, 2016 CTS 054: 4 Scary Things Lurking in Your Wi-Fi
In the spirit of Halloween I wanted to go into a theme of scare and fright. While these may not make the hair on your neck stand, I don’t know maybe they do, these issues can lead to managing a scary wireless network. Scary because of end user complaints and because these can be running on newer wireless networks.
Those four scary things are

* Low data rate clients
* WPA2, even WEP
* 2.4 GHz Zombies
* Non Wi-Fi Interference

But before we jump into those 4 things, I wanted to update everyone on my journey to CWNE. This weekend I decided to take the CWDP exam. After a little under a month of studying I successfully passed.
The biggest resource I used was the official study guide by Tom Carpenter. It covered all the objectives of the exam. I felt this one was easier for me than the CWNA or CWAP. The topics were straight forward and common sense. This is probably because of my experience coming from designing some wireless networks but it came natural for me.
Now I plan on tackling the CWSP. Probably my weakest area but I look forward to learning from the Sybex book that was released in September 2016. I also plan on doing quite a few labs to get the security topics down.
4 Scary Things Lurking In Your Wi-Fi
Low data rate clients
Low data rate clients take longer to communicate over the air. They slow down devices trying to communicate on faster data rates. This makes it an inefficient wireless network.
An easy solution is to disable lower data rates such as 1, 2, 5.5, 6, and even 9 Mbps.
Keep in mind that this will shrink your cell size. So design properly!
WPA2, even WEP
I’ve seen some networks still utilizing WEP. There’s no use for this anymore. It’s been proven to be insecure and newer devices support much stronger encryption. WPA2 is also now crackable so it’s time to use stronger security.
Both security methods are a management nightmare because a passphrase has to be changed on every device.
The best solution here is to use RADIUS as much as possible. Keep WPA2 only devices on a separate SSID.
2.4 GHz zombies
The IoT band. The land of interference. A place where all single band clients get together. 2.4 GHz is a crowded spectrum.
Move your clients to 5 GHz as much as possible to avoid the congestion seen on 2.4 GHz. To troubleshoot issues on 2.4 spectrum use a protocol and spectrum analyzer.
Non Wi-Fi Interference
This also relates to the previous item. Non Wi-Fi interference causes high retransmissions on the network. This leads to low throughput.
End users characterize this as slow Wi-Fi, unusable, and poor performance.
Start looking into causes of anything over 15% retry rate. You can use tools such as Wireshark or Metageek’s Eye P.A.
Check out this previous episode around Spectrum Analysis while you’re at it.
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16min
October 24, 2016 CTS 053: 3 Simple Tips for Passing the CWAP Exam
These 3 simple tips for passing the CWAP exam may seem easier said than done. Listen to the podcast to hear more details about each tip and how I used them to pass the CWAP exam. In September 2016 I sat and passed CWNP’s CWAP-402 exam. The exam costs about $225 as of this episode. […]
The post CTS 053: 3 Simple Tips for Passing the CWAP Exam appeared first on Clear To Send.
...more
19min
October 24, 2016 CTS 053: 3 Simple Tips for Passing the CWAP Exam
These 3 simple tips for passing the CWAP exam may seem easier said than done. Listen to the podcast to hear more details about each tip and how I used them to pass the CWAP exam.
In September 2016 I sat and passed CWNP’s CWAP-402 exam. The exam costs about $225 as of this episode. It’s a multiple choice exam consisting of 60 questions which you need to complete in 120 minutes. The CWAP is the analysis portion of CWNP’s set of certifications.
So let’s go into my 3 tips for passing the CWAP exam:
1. Read The Book Twice
I’ve opted to read the Kindle version of this book. For over a year now I’ve gone completely digital with my books. It works well with my workflow and I hate carrying around heavy books.
The content is very technical so it helps to read through it multiple times in order for the topic to sink in.
My schedule consisted of reading one chapter a week. That was my goal. Some chapters can get very long so it helped to break them out over a couple of days. Pace yourself with each chapter and don’t rush it.
Take advantage of the chapter quizzes. If you score 80% or better, move on to the next chapter. Scored less? Then you need to review. Don’t read the answers for the quizzes. Doing so will make you memorize the answer for the chapter quiz.
2. Take Good Notes
I use Evernote to capture all my notes. You can use other similar apps such as OneNote, Google Keep, or even paper and pencil.
Review each of your notes every day. This will keep the content fresh in your mind. Key things you’ll want to note down are various frame exchanges such as associations and security. Knowing what’s inside of these frames is crucial too, such as what’s inside a beacon frame.
Note down the differences between each PHY and you’ll start to see why that is important.
Another topic I highly recommend knowing is QoS parameters and their priorities.
These little details are good to note down and will be beneficial in your passing.
3. Lab Up Scenarios
A big part of my success if being able to see a lot of Wi-Fi in action. Protocol and Spectrum analysis is a big part of the exam.
I started off by installing Wireshark and using Airtool (Mac app) to capture frames. I got familiar with frame exchanges and what was contained in those frames. I looked at various beacons, associations, and security frame exchanges.
For spectrum analysis I used Metageek’s Chanalyzer. The CWAP book uses Air Magnet. The interfaces differ between Chanalyzer and Air Magnet.
It will be important to spot the different characteristics of interference such as microwave, video transmitters, Bluetooth, and other 802.11 traffic.
Aside from those three tips, experience is a big plus. Having come across many of these topics will help you pass the exam. One such example is troubleshooting wired side issues.
The CWAP exam actually puts some emphasis on the wired side of things because they often mask themselves as Wi-Fi issues. So you have to know how to troubleshoot an issue using the CWAP methodology.
Things I did not take in preparation for this exam:

* Practice exam
* Bootcamp

I felt I prepared enough that I didn’t have to take either the practice exam or bootcamp. I’m not even a fan of doing either. For my CWNA I did take a bootcamp and found it beneficial. I guess at the point I was studying (for both old and new exam) I just got tired of studying and decided to jump into the exam.
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19min
October 10, 2016 CTS 052: How To Validate Wi-Fi Infrastructure
In this episode, I talk with Francois Verges of Semfio Networks about how to validate the Wi-Fi infrastructure. Validating a Wi-Fi network involves many steps. This is not isolated to a new deployment but also to an existing Wi-Fi network. Francois and I talk about what to validate, look out for, and what resources are […]
The post CTS 052: How To Validate Wi-Fi Infrastructure appeared first on Clear To Send.
...more
50min
October 10, 2016 CTS 052: How To Validate Wi-Fi Infrastructure
In this episode, I talk with Francois Verges of Semfio Networks about how to validate the Wi-Fi infrastructure.
Validating a Wi-Fi network involves many steps. This is not isolated to a new deployment but also to an existing Wi-Fi network. Francois and I talk about what to validate, look out for, and what resources are available to assist on the job.
Validate Physical Installation

* Walk through the facility
* Validate

* AP installation
* Antenna orientation
* With the customer
* Telco room location

Post Deployment Survey

* Use your survey laptop and try to use a business critical business device as well (VoIP phone, handheld scanner…)
* Connect to the infrastructure. Use the most business critical SSID.
* Use Ping or iPerf to test connection, roaming, throughput.
* Things to look at while performing the exit survey:

* What band is the survey laptop using?
* What band is the client device using?
* Am I roaming as expected
* RSSI of both your laptop survey and the client device
* If you use ESS, you can also connect 1 or 2 dBx antenna to perform a parallel spectrum analysis. (Detect noise and major interferences)

Things to look at after the survey:

* Coverage
* Channel distribution / Channel re-use

* See if some Tx Power need to be adjusted
* See if some radios need to be disabled (2.4GHz)
* See if more 5GHz channels are needed
* Making sure that all the configured channels are being used.

Spectrum Analysis

* Study both bands: 2.4GHz is usually where you will find the most external interferences
* Stay still at one location. If you see something unusual, move around to pin point the exact location of the source. (might not be easy). – Plan for a little extra time.

Packet Capture

* Get a better idea of the RF environment (using Eye P.A.). Thing to look at:

* Retry rates
* Channel airtime utilization
* Data rates
* How the neighbours can be affecting some channels

* Being able to see more advanced radio configurations such as:

* data rates
* AP capabilities
* Client capabilities (Big one)
* Being to spot unusual behaviours
* Being able to troubleshoot some client issues

Analyze Client Behavior and Configuration

* Make sure all the client devices of the same model have the same Wi-Fi NIC drivers
* Make sure all the client devices of the same model have the same Wi-Fi configurations
* Make sure they manage to connect to the Wi-Fi network (Check delays, does it take a long time to connect?)

Perform Functional Validation Testing

* Grab a client device, roam around the facility (especially where the device will be used)
* Validate how the client roams
* Validate on what band the client connect to
* Try to ping the application server and see if you lose any pings (make sure it does not affect production)
* Validate voice quality if it’s VoIP
* Validate throughput if the requirements need it (try to use the same applications as the one what will be used on the Wi-Fi)

Links and Resources

* Jake Snyder blog
* CTS 039 – When and How To Use Spectrum Analysis
* Mike Albano – Clients
*
...more
50min
September 26, 2016 CTS 051: Aruba Networks at Mobility Field Day Live
Aruba Networks, a Hewlett Packard Enterprise Company, hosts Mobility Field Day Live at their EBC in Sunnyvale to talk about their Mobile First Platform announcement of Aruba OS 8. On September 12th, 2016 Aruba Networks introduced their Mobile First Platform. A platform in which improves upon mobile users’ wireless experience. They’ve really put a lot […]
The post CTS 051: Aruba Networks at Mobility Field Day Live appeared first on Clear To Send.
...more
31min
September 26, 2016 CTS 051: Aruba Networks at Mobility Field Day Live
Aruba Networks, a Hewlett Packard Enterprise Company, hosts Mobility Field Day Live at their EBC in Sunnyvale to talk about their Mobile First Platform announcement of Aruba OS 8.
On September 12th, 2016 Aruba Networks introduced their Mobile First Platform. A platform in which improves upon mobile users’ wireless experience. They’ve really put a lot into developing Aruba OS 8 with extensions to an ecosystem of partners.
Aruba Networks went into great detail of the features being implemented with Aruba OS 8, their new operating system.
Campus WLAN Foundation
Aruba Networks has implemented features customers have been asking for. Features that make it simpler to manage large scale networks.
Introducing the Mobility Master which can be deployed as a VM or a physical appliance. With the flexibility of a VM, engineers can utilize existing infrastructure and if needed, add more CPU, memory, and storage without running into appliance limitations.
A favorite feature of mine with Aruba OS 8 is the ability to terminate different SSIDs on the same AP to different controllers. A lot of flexibility and security using this method. Definitely eliminating restrictions on traditional WLANs.
Going into operations, Aruba Networks introduces zero touch provisioning of new controllers. Controllers can find the mobility master, making it easier on operations.
With the mobility master, it can manage different versions of firmware as long as it is running the latest version. But because the mobility master is not in the data path you won’t see the network go down during an upgrade. With the ability to manage different versions of firmware, you’re allowed to test the latest version on one controller rather than deploying it to all controllers at the same time.
Multizone
For those requiring multi-tenancy, this feature is a huge benefit. The traditional model had access points terminating at a single controller. In Aruba OS 8, different WLANs on the same AP can terminate to different controllers. You now have complete security separation between WLANs and a benefit of not having to install multiple APs for security purposes. This removes the headaches of management and cleans up the RF environment.
Reliability
Controller clustering with stateful failover and load balancing is the cats meow. Within a cluster, you have the ability to load balance users across different controllers. I can see this being used in ultra high density environments such as stadiums. In the event of a controller failure, APs and users are migrated to another controller in the cluster, all without the users noticing a thing.
Do you groan when you have to plan an upgrade to the wireless network? In-service upgrades are part of Aruba OS 8. You can upgrade functions of the wireless network without disrupting APs. Update individual modules without rebooting.
Extensibility
With Aruba Networks ecosystem of partners, you can use APis to gain further visibility into your wireless environment and improve upon end user experience. Check out the videos to see what I’m talking about.
Links and Resources
Mobility Field Day Live recorded videos
Aruba Networks Mobility Master data sheet
Aruba Networks OS 8 data sheet
Aruba Networks OS 8 user guide
Aruba Networks OS 8 release overview
...more
31min
September 12, 2016 CTS 050: Introduction To DAS with Josh Gerst
Josh Gerst and I talk about an introduction to DAS, distributed antenna systems.
Welcome back Josh Gerst, Vice President of Engineering at RF Connect. He originally came on the show back in episode 27 and he’s back to talk more about DAS.
DAS stands for Distributed Antenna System where you take RF from one location and convert it to light over fiber so it could be distributed throughout a facility.
There are many moving parts to consider in a DAS. Some systems use CAT6 cabling and there are traditional DAS systems which use hybrid fiber coax. The hybrid fiber coax method takes multiple RF sources which could be multiple frequency bands. The headend would be used for RF consolidation.
Another system is a multi-sector DAS which is used for capacity. These systems often have 3 sectors where each sector is independent and each sector has different scrambling codes.
Without getting too far into the weeds and keeping this as an introduction to DAS we talk about stadium deployments. Usually multiple sectors are used in these environments due to capacity reasons. A sector may serve 1 or 10 remote units of 20W or 40W. That’s far from an introduction to DAS but it gives you insight into how this can scale.
One thing you cannot overlook with DAS is public safety. E911 is configured for sectors in a tower. Generally phones will log in their GPS on the tower which is then reported to assisted GPS. Public safety generally uses lower frequencies because of the penetration into buildings so we wont typically see it on the Wi-Fi frequencies.
For more of an introduction to DAS, check out RF Connect online and view a couple of videos found online here and here.
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46min
September 12, 2016 CTS 050: Introduction To DAS with Josh Gerst
Josh Gerst and I talk about an introduction to DAS, distributed antenna systems. Welcome back Josh Gerst, Vice President of Engineering at RF Connect. He originally came on the show back in episode 27 and he’s back to talk more about DAS. DAS stands for Distributed Antenna System where you take RF from one location […]
The post CTS 050: Introduction To DAS with Josh Gerst appeared first on Clear To Send.
...more
46min

FAQs about Clear To Send: Wireless Network Engineering:

How many episodes does Clear To Send: Wireless Network Engineering have?

The podcast currently has 467 episodes available.

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