Correct Elevation and Azimuth Wi-Fi antenna angles in Cisco DNA Center for ceiling mounted AP

This question comes up and every now and then. So, let’s put it to bed.

If you have a ceiling mounted internal antenna AP (with built-in antennas), or external antenna AP with dipole antennas (AIR-ANT2524D), or with short dipole antennas (AIR-ANT2535SD), here are the correct Azimuth and Elevation angle settings.

This is how 0° Azimuth and 0° Elevation look like. Plus “squished doughnut” as a bonus to illustrate the coverage pattern 🍩
  • Azimuth angle does not matter in this case (it does for directional antennas), because these antennas have the same pattern regardless of how you rotate them clockwise or counterclockwise. Simply use the default value of .
  • Elevation angle is for this orientation.
Cisco DNA Center Azimuth and Elevation configuration

Special thanks to Christian Gauer for his help.

Will 20 MHz capable Wi-Fi client join an SSID using 80 MHz wide channel?

Let’s take this “Back to the basics” question and test things out.

So, we have this 20 MHz capable Windows 11 Wi-Fi client and we want to see what happens when it attempts to join an SSID that uses 80 MHz wide channel. Will it associate? Will it fail?

Here is my client with Intel AX201 adapter forced to only support 20 MHz wide 5 GHz channel.

My AP uses 80 MHz channel width.

Let’s verify the settings from a Mac. Yes, the AP broadcasts 80 MHz wide “lab5” SSID with primary channel 36.

Finally, what happens if the client device is only capable of 20 MHz channel width? As you can see, it will happily join using Primary channel 36.

More capable client devices that support 80 MHz channel width will benefit from the 4 bonded channels and use the 80 MHz channel in its entirety.

Portable Catalyst 9136 Wi-Fi 6E demo powered by Zyxel 802.3bt power injector

I am building a portable Wi-fi 6E demo in a box solution. What do I use for that?

PoE powered FriendlyElec’s NanoPi R5S runs iperf3 server. Here a quick iperf3 performance review of this little, 2.5 GbE, and mighty Linux box.

My Catalyst 9800-CL controller is hosted on a cloud, so I don’t need any hardware for that. Finally, my Catalyst 9136 Wi-Fi 6E AP is powered by a Catalyst 3560CX 10 Gigabit Ethernet multigigabit switch.

6 GHz 2×2 MIMO setup powered by PoE+

Catalyst 9136 is Cisco’s premium AP with all the bells and whistles including hexa-radio architecture and built-in environmental sensors for smart building use cases. It requires an 802.3bt/UPOE power source to enable 6 GHz radio in full performance 4×4 MIMO mode. The switch I use supports 802.3at/PoE+, which is great, but 6 GHz radio downshifts to 2×2. And that’s where an 802.3bt power injector comes to the rescue.

Zyxel 5G PoE++ Injector

Cisco’s 5 GbE 802.11bt power injector (AIR-PWRINJ7=) is now available, and that’s my go to option for production use.

Since the Cisco injector isn’t widely available yet, I decided to test this Zyxel one. It provides 802.3bt power and allows the AP to run in full power and full 4×4 6 GHz radio mode with no compromise.

Do I like power injectors in production?

Absolutely not! Ideally you should design for 802.3bt/UPOE switches to power all your new APs via PoE.

It allows you to:

  • easily, centrally and remotely monitor how much power the APs use
  • enable/disable power on a port to bounce an AP
  • leverage redundant Platinum-rated power supplies for the AC to DC power conversion
  • manage the solution with ease – just think how difficult it is to manage more than 1 power injector, the number of AC power sockets, and what happens when someone disconnects the injector?
I still use C3650 UPOE mGig switch in my lab. Catalysts 9300 and 9400 the best choice these days.
UPOE and mGig capable C3650 providing full power to the AP

Final look

Carrying a full-size switch is not really an option for me, because small form factor is my main goal. So a power injector works best for me. But if I could I would love to use a compact 802.3bt switch.

Are you wondering if the PoE splitter connected to my iperf3 server (the little black box with 3 Ethernet interfaces) actually negotiated 2.5 Gbps Full duplex with the switch? Yes, it did. But keep in mind that the PoE splitter is technically only rated for 1 GbE. So use as short patch cable as possible and ideally CAT6.

Still few things to tidy up and perhaps I could build this into a nice Pelican case

Cisco Catalyst C-ANT9103 antenna unboxing

If you have not had a chance to see the new Cisco Catalyst antennas for Catalyst 9130AXE access points, here are a few photos of the C-ANT9103 antenna for your reference.

Size, weight, mounting options

The official installation guide provides all this information and much more.

The optional access point “pocket”

Optionally, you can order an AP + antenna collocation “pocket”, which the Catalyst 9130AXE slides nicely in. It is aesthetically pleasing it, and all it takes to install the AP and antenna is a single mounting bracket. You don’t have to worry about mounting the access point and antenna separately. This drastically simplifies temporary deployments – just think about Cisco Live for example.

Previous generation with a separate AP bracket and antenna bracket
The new collocated, and aesthetically pleasing, solution with AP installed just behind the antenna

Unboxing

Please always refer to the official Cisco documentation for the latest information and package contents.

Affordable tripods for occasional Wi-Fi site surveys

As I mentioned in my battery pack review, I am fortunate to rely on our field engineers and partners when it comes to predictive design validation, wall measurements and AP on a stick surveys. Having said that, I enjoy going on site a few days a month and staying close to our projects. Which leads me to yet another blog post from the “affordable series”;-)

This time I tested 3 tripods. Key factors I considered were value for money, build quality, and suitability for outdoor surveys ability to hold anything from an indoor or outdoor AP to a camera.

Tripods

Left to right/up to down:
(A) Neewer Stainless Steel Heavy Duty Light Stand 118″/300CM
(B) Phot-R 4m Heavy Duty Photo Studio 2-in-1 Combi Light Boom Stand
(C) Neewer Heavy-Duty Light Stand 13 Feet/4 Meters Spring Cushioned Aluminum Alloy Pro Tripod

Maximum height comparison
Collapsed length comparison
Width of the base is comparable, see the slabs

The numbers don’t lie

Tripod ATripod BTripod C
Collapsed length104 cm112 cm115 cm
Measured max height283 cm366 cm393 cm
Weight2.45 kg2.55 kg5.9 kg
Price£65£70£68
Short summaryVery good, not tall enough for outdoor surveysUnstable, too light, loose locking mechanism, unsuitable for holding APsGreat value for money, rock-solid, tall, heavier

Summary

I decided for tripod (C). It is high enough for outdoor surveys, rock-solid, and very stable. I also built an adapter that allows me to easily mount any outdoor Cisco AP (Catalyst, Aironet or Meraki MR). Here is more about my outdoor Meraki MR universal tripod adapter. Stay tuned for the Aironet and Catalyst one.

The only downside is its weight. Also, watch out for packaging. The first one I ordered arrived with the bottom of the box open and the head, where you insert the 1/3″ and 3/8″ adapter, was damaged. So, it took one return to get an undamaged one.

 All three tripods are supplied with 1/4″ to 3/8″ adapter.

Neewer 4-meter tripod in the wild
Even the replacement one had some extra tape applied, fortunately undamaged this time

Affordable battery pack for occasional Wi-Fi “AP on a stick” site surveys

Since I don’t survey every day, I could not justify the purchase of a full-blown battery pack. My goal is to get a universal battery pack, which would allow me to survey for 5 hours and provide power to my laptop or USB device (like the WLAN Pi) at the same time.

A quick research made me to test the RAVPower AC 27000 mAh Power Bank. Here is what I’ve learned after using it for a few days:

  • The 2 built-in fans kick in when AC device starts drawing more than 20 Watts. Below this threshold, the fan is off. With the fan on, it actually becomes annoyingly loud (watch this video).
  • The AC inverter seems to operate with 82% efficiency
  • MacBook Pro 61 Watt power brick charges the battery using USB type C port
  • It powers USB devices and 230V AC devices (power injector in my case)
  • Capacity of 99.9 Wh

Things I like about this battery pack:

  • It is universal and power USB and AC devices
  • Its size and capacity are great

Things I don’t like:

  • When AC load exceeds 20 Watts, the 2 fans become generate significant noise
  • The adapter from its AC socket to UK socket is really poor, does disconnect very easily and cuts power. This is a huge downside.
  • AC power automatically switches off when the connected device draws less than 8 Watts or so. If you need to power a very low power device, use the USB port or plug one more device in to increase total load.

Battery life tests

I tested a few access points powered by a PoE+ 802.3at injector:

Cisco Catalyst 9115 in site survey Embedded Wireless Controller mode stays powered for 6 hours and 24 minutes and draws around 13 Watts.

Cisco Aironet 1560I (in 2SS only mode) in Mobility Express site survey mode stays powered for 5 hours and 28 minutes and draws around 15 Watts.

Formula to estimate battery life

Cisco Aironet 1540I draws around 8 Watts (measured by a smart plug) and estimated battery life is:

Run time = Battery capacity in Wh * Battery inverter efficiency / Power drawn by device in Watts = 99.9 * 0.82 / 8 = 10.2 hours

Tested devices powered by AC power

MacBook Pro (13-inch, 2019, Four Thunderbolt 3 ports) powered using MacBook 61W USB-C power adapter connected to the battery pack charged the laptop with no problem. The only annoyance is the battery fan noice. I can’t imagine using this in an open plan office as it would disturb others. Charging while on site or in a car is not a problem.

I was able to power Cisco WLC 2504 and 3504 with no problem at all and they drew around 25 Watts. You can use the above formula to calculate estimated battery life.

Cisco Catalyst compact switch WS-C3560CX-8XPD-S is not able to be powered by this battery, the battery goes into overload mode and cuts power. I suspect the AC wave output of the inverter is far from “perfect sine” and it prevents some devices to be powered. A different battery pack with better filters would be my suggestion if you need to power a device like this.

Another Cisco Catalyst compact switch WS-C3560CG-8PC-S works perfectly fine and draws about 17 Watts with no Ethernet ports connected and no PoE provided to its downstream devices.

Maximum AC load test

It tried connecting as many devices to the battery pack and power them using the inverter. These devices can be powered concurrently just fine:

  • Cisco Meraki MS220, Cisco Small Business SF100-08P switch, Aironet 3800 AP, Catalyst 9105AXI AP, Aironet 1800S Wi-Fi active sensor, Aironet 1560I, MR32 AP, MR20 AP, Aironet 1815W, a Bluetooth speaker and Raspberry Pi 4

How I fixed the supplied AC adapter issue

As I mentioned, the provided power adapter is a joke and not fit for purpose if you want to connect a device using a UK power plug. Just the weight of the power cable itself pulls the adapter from the battery pack socket and stops power supply to the connected device.

I decided to keep the battery pack as everything else works quite well and I replaced the provided adapter by a power cable with European plug and IEC C14 to UK socket “UPS” power adapter. This on its own stays connected in the battery inverter’s socket quite nicely and I added a couple of velcro straps to keep it securely in place at all times.

Fan noise