[Make-wifi-fast] Re: [Rpm] Re: [Bloat] Re: [Cake] "Fi-Wi is a new forwarding plane for wireless" - Bob McMahon

[bob.mcmahon@umbernetworks.com]

Hi Frank,

The question needs to be framed in measurable terms.

The systems you named operate at different layers than the 802.11 
MAC/PHY layer where TXOP allocation, retries, EDCA contention, AMPDU 
behavior, and airtime utilization occur throughout the building. 
batman-adv routes between mesh nodes. CAKE and FQ-CoDel operate on 
IP-layer queues. QoE middle-boxes operate from the WAN/IP side.

So the question is whether IP-layer AQMs or WAN-side QoE systems affect 
measurable 802.11 MAC/PHY behavior under load.

If they do, the predicted MAC/PHY effects would include:

  	* lower failed TXOP percentage
  	* lower retransmission airtime fraction
  	* improved AMPDU completion efficiency
  	* higher payload delivered per TXOP
  	* lower AMPDU truncation frequency
  	* reduced EDCA wait distributions
  	* improved airtime utilization
  	* reduced service-time variance
  	* changed MCS distributions across stations under realistic spatial 
topology, particularly at coverage edges and where multiple APs or RRHs 
are candidates for node selection

That is the measurement gap I am pointing at. The industry has extensive 
802.11 feature lists and marketing claims, with comparatively little 
open tooling to falsify what those actually do to building wide 802.11 
MAC/PHY behavior under real multi-client, multi-AP load.

I developed and still maintain iperf2 because throughput alone has 
proven an insufficient measurement model for network behavior, e.g. 
latencies and responsiveness under load. Features added to iperf2 
include:

  	* trip-times
  	* bounceback testing
  	* one-way IP packet timing measurements
  	* packet-level latency histograms
  	* message-level (TCP write/read completion) latency histograms
  	* responsiveness under load measurements
  	* enhanced per-interval reporting
  	* CWND reporting
  	* RTT reporting
  	* bytes/packets in-flight reporting
  	* TCP retransmission reporting
  	* TCP congestion-control selection (CUBIC, BBR, Prague, etc.)
  	* udp-l4s including CE counters and durations
  	* isochronous traffic generation
  	* socket-layer pacing via SO_MAX_PACING_RATE
  	* token-bucket write-rate control
  	* Markov-chain packet-size generation
  	* UDP latency/jitter analysis
  	* multicast testing

Those measurements operate above the 802.11 MAC/PHY. The missing layer 
remains open 802.11 MAC/PHY telemetry, which is what I'm building now.

This measurement standard should apply equally to any claim from any 
architecture, including Fi-Wi.

The question becomes: does centralized MAC telemetry and coordinated 
airtime control affect measurable 802.11 MAC/PHY behavior under load 
relative to autonomous AP operation?

Measure the same MAC/PHY metrics under equivalent topology, offered 
load, and client mix. If those measurements do not improve relative to 
baseline, the architectural claim of Fi-Wi fails. We won't know until 
Fi-Wi is designed, built, deployed and measured at many different 
locations. The theoretical case is strong.  Centralized scheduling, 
joint optimization, and observability all argue for it. The design and 
measurements are the next steps. Then we'll see based on evidence.

Bob

> Technically, Betamax was superior to VHS, and yet...
> 
> If we would be talking about FiWi pre-jump from Wi-Fi 5 to Wi-Fi6/E/7, 
> I would even try to do my best and ignore https://fastgood.cheap.
> But we are not there, for better or for worse.
> 
> ISPs like Dan that use Wi-Fi 6 (with mesh, especially based on 
> batman-adv and FQ-CoDel / CAKE) and above at customer premises and 
> Quality of Experience middle-box on their last-mile, while providing 
> good, personal customer service (not some crappy outsourcing of it to 
> India or "AI") will be hard to beat, even for a big telco/ISP offering 
> cheaper price. Yes, some people will leave but the most of them will be 
> coming back.
> 
> This is, believe it or not, not a high bar to jump over, even though 
> not many ISPs are getting it already. We all know that more or less: 
> "Bandwidth is a lie, Bandwidth is dead," so it's coming. They will be 
> throwing more bandwidth on it for some time, but we will be getting 
> from "innovators" to "early adopters" soon and then, all we need is 
> just that "crossing the chasm."
> 
> Despite all the difficulties, it will be faster and cheaper - also 
> "good enough," than FiWi. Or rather, it's here already, it's just not 
> evenly distributed.
> There might be some good niche use case for FiWi, though, once it will 
> mature and get there.
> 
> All the best,
> 
> Frank
> 
> Frantisek (Frank) Borsik
> 
> In loving memory of Dave Täht: 1965-2025
> 
> https://libreqos.io/2025/04/01/in-loving-memory-of-dave/
> 
> https://www.linkedin.com/in/frantisekborsik
> 
> Signal, Telegram, WhatsApp: +421919416714
> 
> iMessage, mobile: +420775230885
> 
> Skype: casioa5302ca
> 
> frantisek.borsik@gmail.com
> 
> On Sun, May 24, 2026 at 2:12 AM dan <dandenson@gmail.com> wrote:
> 
> On Sat, May 23, 2026 at 10:36 AM <bob.mcmahon@umbernetworks.com> wrote:
> 
>> I don't have arguments on the technical bits of your reply.
> 
> The industry hasn't provided open source tools to analyze 802.11 
> properly. The proprietary ones are tightly coupled to chip firmware, 
> owned by 802.11 vendors, and not for sale.
> 
> You've built solid networks, especially given how little 802.11 
> MAC-layer and MCS observability current tooling exposes. I hope to make 
> open source 802.11 MAC telemetry tools available sooner rather than 
> later. These will run on both an ESP32-C5 and an RPi5. The inexpensive 
> ESP32 allows monitors to be placed throughout a venue at low cost.
> 
> A key issue is what's being measured. Your deployment data is a 
> capacity analysis. Once baseline capacity is adequate, user experience 
> is driven by tail latency and service-time variance rather than 
> throughput. A network can saturate aggregate throughput while still 
> showing large service-time variance and long per-flow tails under 
> contention. These are different measurements.
> 
> And CODEL and CAKE are IP-layer mechanisms. They don't operate on 
> 802.11 TXOPs or airtime sojourn, which is where the contention and 
> service-time variance actually live. AQL is closer. It operates on 
> airtime at the driver/firmware boundary, but it's still per-AP. There's 
> no coordination across APs and no MAC telemetry exposed upward.
> 
> Slide 6 of my DPDK Summit Stockholm talk lays out the layering: 
> https://www.umbernetworks.com/DPDK_WiFi_Stockholm_Pres.html
> 
> Check out iperf2's advanced features around --bounceback, --trip-times, 
> and --histograms. These are available as open source. Man page: 
> https://iperf2.sourceforge.io/iperf-manpage.html
> 
> I'll try to respond with some metrics soon. My rig is down at the 
> moment, so give me a few days.
> 
> Bob
> 
> I agree.  However, I'm not actually just measuring throughput, but 
> running latency sensitive applications without issues.  Frank might 
> attest to my efforts to reduce latency and I routinely share data on 
> lqos (and another QoE product's) TCP measurements for latency and among 
> QoE users, I believe my network is top 1% in latency and jitter and in 
> the WISP space.  Obviously I'm not going to compete with XGSPON 
> operators.. (though I'm only measuring TCP because that's the 'easiest' 
> to measure passively practically).  While this is not an engineering 
> adequate benchmark, if my VoIP handsets work over wireless then the 
> wireless is good is a very reasonable latency, jitter, loss argument.  
> And I run a few brands of WiFi based VoIP phones (Fanvill Wxxx series, 
> Yealink Wxx and AXxx series).  Similarly, if the sonos works and is in 
> sync, the wifi is good.
> 
> As a service company and as a user, I don't really care so much where 
> the goodness is in the system, mac layer or IP having cake work it's 
> magic.  Basically running an AP on OFMDA (as much as possible) and well 
> under the 'red line' capacity delivers great results on WiFi7 radios 
> (and some WiFi6 radios).  I have no doubt that FiWi could get more of 
> the theoretical throughput delivered at the mac layer.
> 
> Deliverables are all that matter to me and I think to buyers and users. 
>  Benchmarks test deliverables which is great and I'm a routing iperf* 
> user.  It's engineering's problem to develop the next tech *AND* 
> solicit funding to do so.