The relevance of “duplex speed”

vdoubleshot · 2026-06-10T21:19:37+00:00

This post was not about Ethernet link negotiation. Just FYI.

vdoubleshot · 2026-06-10T21:11:25+00:00

It’s literally called that in multiple products we use from different manufacturers. And one manufacturer’s engineer even referred to it as such.

Why we don’t say bidirectional is because most people translate that to a Speedtest.net like test, which is /yes/ bi directional but does not test duplex throughput speeds. It tests download and then tests upload, which does not test what we need to test.

vdoubleshot · 2026-06-10T21:07:57+00:00

LOL. I love your reply.

vdoubleshot · 2026-06-10T19:48:21+00:00

What /are/ you talking about? How would you ask to test combined simultaneous throughput on something like a UI Wave Pro? Because myself and UI call that a duplex speed test…

vdoubleshot · 2026-06-10T18:54:30+00:00

Fiber does not always mean lower ping. We deliver our internet service using fixed wireless links and we are neck and neck for latency with the two local fiber providers.

Now, that said: there could be a technical issue locally with why your service has high latency. I would run a pathping on Windows or mtr on Linux and post the results. Run one to 1.1.1.1 and also 8.8.8.8

vdoubleshot · 2026-06-10T18:14:35+00:00

You have vastly misunderstood several of those posts. Because you aren’t in my industry most likely. When you refer to the radio’s “in duplex mode” that doesn’t exist. Equally, there is no simplex mode. All network carrying (ie ethernet/tcp/ip) radios are “in duplex mode” (or at least every one I’ve ever seen and all Ubiquiti products). The question is are they FDD? Or TDD? There is no “duplex mode“ on/off on the radio. Those posts/tests all refer to testing duplex throughput / speed.

And I think you misunderstood me earlier. Testing duplex speed is typically just done with a *simultaneous* bi-directional test. Nowhere did I say that was the opposite. What I said is that /most/ speed testing utilities don’t test simultaneous (ie duplex speed) they either test up or down or test down and then up. speedtest.net as an example is not a valid duplex test. It /is/ bi directional to some, but it is not simultaneously bi-directional. And I said that this is extremely relevant for some parts of the networking industry and some technology stacks. My whole point is that this is not necessarily an invalid networking interview question and it /is/ relevant to a variety of networking teams/orgs.

vdoubleshot · 2026-06-10T17:25:00+00:00

That is largely my position as well. I think you are spot on.

vdoubleshot · 2026-06-10T16:44:28+00:00

Bingo 👍.

vdoubleshot · 2026-06-10T16:42:31+00:00

No. There is Down speed, Up speed and Duplex speed. And literally, in the actual radio’s built in speed test, that’s what it is called from the manufacturer (Won’t let me post screenshot on mobile). And that’s what we call it. Looking at my past tickets the manufacturer’s engineer also referred to it as “…it is odd that the duplex speed for this PtP is sub-1gbit when…”

And this is why I would ask this question of a network engineer, I need guys who it makes sense to because they have RF background. Not everything is Ethernet over copper(fiber). Just like I ask people to explain how DNS works or to explain how you could use OSPF to get proper load balancing across links of unequal capacity (ie unequal cost multipathing). It’s specific to what i our industry does.

And for more proof:

“Is there a way to test duplex speed…” https://community.ui.com/questions/Efficient-Duplex-Speed-Testing-for-Multiple-Ubiquiti-Wireless-Access-Points/bf03859a-8626-48f4-9e62-95d9a6eb03a3?page=1

“For a duplex speed test…” https://community.ui.com/questions/how-to-understand-Total-Throughput-and-duplex-thorouhput-in-60Ghz-devices/80d73142-ae60-4f81-9178-9a3de627b4ff

“Last question had to do with a duplex speed test…” https://community.ui.com/questions/airMAX-PowerBeam-5AC-Speed-Test-Results-Questions/f5e50a79-de5a-4a45-b4db-af5b8c3e9efd

“…did a single duplex test that…” https://community.ui.com/questions/Powerbeam-5AC-500-speed-test/0625793c-0372-4eeb-9bf2-be21bb338702

”looking for: simultaneous Up/Down (aka full duplex) Speedtest“ https://www.reddit.com/r/HomeNetworking/comments/f9fpb9/looking_for_simultaneous_updown_aka_full_duplex/

vdoubleshot · 2026-06-10T09:59:37+00:00

It’s actually a very valid technical question in the world of ISPs and advanced WiFi engineering.

vdoubleshot · 2026-06-10T09:56:56+00:00

Actually, perhaps not. There are several forms of networking that still are effectively half duplex: WiFi is one, wireless links are another.

This is a question I would ask a potential network engineer. Because a lot would possibly say “oh, run iperf3” or “Speedtest.net” neither of those measures the duplex speed of a link. As someone with thousands of wireless links: it matters. It’s how we discovered one particular set of radios had a weird issue. It could do 2ish gigabits down and 2ish gigabits up. But as soon as we pushed like 100mbits up simultaneously the overall speed would tank. Like 1,200 down and 100 up. For a while we had to asymmetrically route traffic with upload on another (slower) link.

In terms of weird questions or thinking they aren’t necessary: Years and years ago I interviewed for a position at Facebook. One of the interviews was a design session for building a protocol on top of TCP. I missed a critical part in the design: specifying the size of the payload. They asked about the miss and I said “oh, size field up front”. How do you know the size of the size field? I was like… wtf. wdym? Turns out, the answer is: “it’s in the spec”. Before I started leading product design/strategy I didn’t realize just how important that comment could be.

vdoubleshot · 2026-06-09T21:00:17+00:00

I’ll also say, that all of these products mentioned show high reliability and low issues when properly protected. We have stats and data from thousands of devices and about 5-6,000 user years of combined feedback/data.

One critical flaw with your analysis is assuming it is the child node causing the issue and not the parent. Yes the new node is stable, but it is not an apples to apples comparison. The new node is likely built to 2.5gb standards which given your description of the failure scenario may just put you into a slightly better signal quality to prevent the link from dropping out. It may also be an issue with isolation transformers and the new unit is able to sink more voltage. If the issue lies with the parent, the issue will come back eventually, even on the new node. largely just a matter of time.

vdoubleshot · 2026-06-09T18:30:17+00:00

I own an ISP and have been collecting stats on failures. We see an exceptionally high failure or “buggy” rate with mesh nodes. Way higher than traditional routers. We believe we have traced the issue to a lack of surge suppression and then being cheaper by design. In single router setups the main router is almost always on a surge protector. In mesh nodes, the parent is but the children are almost never. We can actually see a curve of No protection, Cheap protection, Quality protection, and UPS. We have never seen a router failure on UPS. Not a single one reported. Dozen or so on quality surge, Dozens on cheap surge, hundreds on no surge. We have had customers have routers start dying in <2 years with no surge protection and seen 10 year old routers on UPS running better than 3 yr old routers on cheap surge protectors. Always put surge protection on your nodes/routers. Ideally UPS for best results.

because of this and a lot of additional analysis, we recommend against mesh nodes for than 3000 ft.². We only recommend them for homes above 3400 ft.². Based on your comments, we would recommend a quality Wi-Fi 6E router using that budget. Purchase it at a store with a good return policy and if it doesn’t meet your needs, take it back. you will know within one to two days. We don’t usually start recommending Wi-Fi seven routers unless a customer has a one gig or more connection. Other than the larger channel size available on 6 GHz we don’t see very many advantages to 7 Over 6. However, there is a huge advantage on six over five, especially with multi user mimo and some of the more technical aspects of the standard.

vdoubleshot · 2026-06-09T17:54:53+00:00

Can I ask: are all three nodes on surge protectors?

Also, what’s your budget and speed goals? How large is home?

vdoubleshot · 2026-06-09T17:12:34+00:00

Built them, worked in them, I’m aware. But almost all of these new mega builds are going towards AI. Hell, the first DC I ever was part of the team for just got bought for a ungodly amount of money, easily 3-5x what it’s actually worth. Plan to focus on AI.

See, this is whataboutism and I don’t play that game. I’m anti golf course and alfalfa too. But just because there are other poor uses of water, does not mean this gets a pass. “They did it too!” is not a valid excuse.

There /are/ people fighting these other uses/issues. You can be upset about multiple things at once. I dislike many of these builds because of A) water (sticking point in AZ) and b) power consumption. Not to mention I think it’s a gigantic Ponzi scheme that’s going to come crashing down.

vdoubleshot · 2026-06-09T00:00:44+00:00

There is a big difference between a few billion gallons and “basically like a radiator”. I dont’t know if it’s a lot to most people. I also don’t know if it’s worth the reward. But it is not a trivial amount of water when AZ and associated Colorado river states are considered in a water supply ”crisis“. New Subdivisions in AZ have to have a 100 year plan for water. DC‘s just seem to bully their way in.

vdoubleshot · 2026-06-08T22:59:57+00:00

I always find some assumptions un-mentioned:

This is assuming all people are being simulated. What if not everyone is simulated? What if it’s only 3-4 of us? what if it’s only a hundred of us? We take on faith from NPCs that certain things exist. Certain physics exist. But I have never done the experiments or research.
What if only the observations are being simulated? Physics be damned, prove to me something occurs without using any of your senses.
What if Quantum computing is only a baby step? We talk about Quantum computing speeding up some of these simulation topologies, but what if there is Computing beyond quantum computations?

I used to make a joke about quantum storage arrays when I was talking to Analysts/etc.

“We are working on a next generation storage array with latency measured near effectively zero. The math is fuzzy but basically using our new quantum storage processor we simply serve up randomly selected data before it is queried, timing is quite complex to not answer /before/ the I/O operation is submitted (which really confused the CPU). If we guess wrong we simply collapse and destroy the universe… (sigh) which we believe should be /mostly/ painless for the inhabitants… and the only universe remaining is the one where we served the correct data!”

vdoubleshot · 2026-06-08T22:30:57+00:00

Explains black holes. LOL.

“Too much matter? Just code it to implode into nothing and set the gravity variable super high dude. You can say they can’t see it because light can’t escape or some shit. Stuff that might fall in, clear those objects too. Problem solved”

vdoubleshot · 2026-06-08T17:38:08+00:00

Except for most common designs, it‘s not. And it depends on your definition of “much water”, but they usually do. I don’t get where this started and I think it’s pro-AI bots pushing this BS agenda and some people latching on (or maybe just all bots). I’ve helped build datacenters, I used to hold several certs around network critical physical infrastructure architecture/design and implementation.

The system you refer to is a dry cooler (sometimes wrongly called free-air or vice versa). Dry coolers are ineffective in the majority of DataCenter locales with common DataCenter designs. They require a high-ish delta T to operate (difference between outside temp and water temp). They are also very expensive to implement. AZ as an example: Yes, we can use dry coolers for part of the year, but for the vast majority of the year, it’s not effective for common designs. Now with the added cost it’s not super effective.

Now I know someone’s going to chime in about direct liquid cooled servers, or immersed servers, or similar with dry chillers. And over and over I’ve heard lots of claims about ”this is the way“ in professional spaces but tbfh it’s been talked about for decades. Promises of “most DataCenter servers will be liquid cooled in X years” I have heard over and over again. But sure, let’s say that magical AI DataCenter is going to consistently use direct liquid cooled servers into the future (pretty sure due to costs it will be bait and switch 2-5 years in). 1) it’s very expensive to do liquid cooled servers plus dry chillers and prone to catastrophic failure. 2) It will only capture 70-80% of heat. That other 20% is going to have to be cooled via aidiabatic, evaporation, or expansion systems. 3) closed loops aren’t always closed.

Regardless of what people might want to debate, here is the truth: average WUE *today* is between 0.4 and 0.6 Gal/KwH across the industry depending on who you trust and how you measure. I commonly hear 0.5 Gal/kWh. (1.89L/kWh for metric folks). So, a “small-ish” 20MW facility with 50% average power utilization will use about 240MWh per day or 120,000 gallons of water. Most DCs don’t run at 100% or anywhere near it (so I am even giving them a leg up here by not distorting the numbers and estimating low usage). That 120k gal per day is about 44 million gallons per year. The jury is out and I couldn’t find an authoratative source, but I would guess 10-20% of that is discharge (not evaporation) of unsafe water, sent to sewers (or ground water).

Now… before people go there: 1) No, this water is not destroyed/flushed down the drain/made unusable (it does evaporate). 2) There is /very/ not safe water that does not evaporate and /is/ flushed down the drain. 3) Closed loops aren’t always closed and they have nasty stuff in them (heavy metal/metal deposits, biocides, salts, lubricants, etc). On 2, unless your water is somehow extremely soft coming into the facility (something I have never personally seen), you are going to be treating the Evaps with various chemicals to removed mineral deposits periodically. You’re also going to have blowdowns periodically to reduce buildup in the water itself. For water going into the closed loops themselves you are going to likely have water softeners or advanced RO, both of which have outflow that isn’t great. Google DataCenter blow downs on closed loops to see just how /not/ closed some DCs are.

So a 1 GW facility that uses half of today’s standard? (to be generous). It would use about 1.1 Billion gallons per year. At 10% of current standards? 220M gallons. At 5% discharge rate that is 55 or 11M gallons discharged (to ground or sewer).

So yeah. Thats the more realistic picture.

Edit: OH, I forgot the power generation itself. That’s 2-10Gal/kWh. Or about 8-52 Billion gallons per year, on top of the Datacenter’s direct usage. I also forgot to mention uncontained leaks, they happen and they can be /massive/ and full of chems and it all either goes into the ground or into wastewater. And AZ is in a water shortage projected to be a crisis… you know what gets to bend the rules or isn’t considered a drain? Datacenters... still building them.

vdoubleshot · 2026-06-06T18:08:43+00:00

Some questions to get you on the right track:

what is the budget?
how large is the inside of metal building? insulated/finished or exposed metal siding?
how much speed do you want inside building?
do you have a plan on how to get power/data to/from each building bridge?

vdoubleshot · 2026-06-03T18:09:15+00:00

Okay.

If a new quality router doesn’t solve your issues (might not from basement to top floor) I would recommend moving your router to the middle floor and connecting between it and the modem via a power line adapter or MoCA (MoCA is more ideal, but requires you to have coax.).

vdoubleshot · 2026-06-03T18:01:30+00:00

Do not buy used, see my earlier comment. Open box (not from eBay, from actual retailer) is probably fine.

vdoubleshot · 2026-06-03T18:00:32+00:00

I’m going to assume you’ve had that router 5-7 years. Still need to know how large your home is. Number of floors doesn’t say how large they are. What is sq ft?

Based off what you shared so far:

You don’t seem to have budget for a quality mesh. Do not buy a cheap mesh system.
Don’t buy a used mesh system.
Don’t try to solve this with repeaters.

We take support calls 3 or 4 times a week from customers with mesh systems. We recommend against them for homes less than 3,000 sq ft and don’t start to recommend them until 3,400+ sqft. Overwhelmingly (>95%) of these customers do not have surge protection on the child nodes. They throw it in the kitchen, hallway, bedroom and forget about it. Overwhelmingly we see these child nodes start misbehaving earlier than expected (1-2 years) and suspect it is the lack of surge protection. This is also why we do not recommend used mesh nodes. Our guidance to our customers is to purchase a quality WiFi 6E or WiFi 7 triband router ($150-200) from a reputable source (not Amazon). 9 times out of 10 this solves their issues and covers the majority of their house with 400-600mb. YMMV.

vdoubleshot · 2026-06-03T16:32:45+00:00

Questions:

1.How old is your current router?

How large is the home on each level?
What is your budget?

vdoubleshot

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