AirCube AC - 350 mbit maximum WiFi speed? CPU Load ~100%

[gmont]

Hi there, 

I've got 1 gb connection recently and noticed that AirCube is limiting me to ~350 mbit due to cpu load. Is that as expected or something is wrong? 

AirCube is connected as bridge to router, router is not limiting it (I'm getting my gbit over ethernet). Client Killer Wireless-AC 1550 is connected via 5Ghz, client speed caps somewhere at 650 mbit. 

[UBNT-JoshMcGee · Accepted solution]

Yes, this product is not targeted for such high throughput demographics. It's intended for users of the typical WISP operator who don't get hundreds of megabits to the home.

For needs like your gigabit uplink, edgemax and AmpliFi are recommended instead.

[UBNT-JoshMcGee · Accepted solution]

Yes, this product is not targeted for such high throughput demographics. It's intended for users of the typical WISP operator who don't get hundreds of megabits to the home.

For needs like your gigabit uplink, edgemax and AmpliFi are recommended instead.

[gmont]

So how can I get speed from Datasheet? or at least close to it? 

I would understand if I get like 600 mbit instead of 866, but I get almost 3 times less than specification promises me. Please understand me right, 350 mbit is not anywhere close to 866. 

https://dl.ubnt.com/datasheets/aircube/airCube_DS.pdf 

[jonwang]

I'm just too curious to not ask... what are you doing over WiFi that you need more than 350Mbps?  Anything that wouldn't work just the same if it were 30Mbps or are you just worried about chasing numbers?

I get similar questions from customers all the time.  I'm genuinely curious, not trying to be a punk.

[jonwang]

Are you aware that those numbers are air rate numbers not actual throughput.  Its sort of like a cable negotiation at 10/100/1000.

[eejimm]

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@jonwang wrote:

Are you aware that those numbers are air rate numbers not actual throughput.  Its sort of like a cable negotiation at 10/100/1000.

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Right - the "over the air" rate for WiFi is basically double the best actual throughput you will see.   It's a marketing thing the industry started 20 years ago (before Ubiquiti even existed) and everyone has to use it or their printed numbers look bad.   Technically it's about overhead and the actual modulation and error correction protocols used over the air.   Take whatever the published numbers are and cut them in half, basically. 

As to why people want so much over WiFi, we get the  same questions all the time, and it usually is because people want what they think they should get.   The bigger issue is when you get a number of devices on an AP at the same time - WiFi doesn't scale very well.   In tests with very good signals and a very fast AP in 5GHz with no interference but 20 devices all doing "normal" stuff (ie no streaming video etc.) the max speed possible dropped to under 30Mb even though the raw numbers said there should be way more.   It's due to the way WiFi works and how multiple clients all contend for the connection.   We build large hotel and outdoor venues that can handle over 10,000 connections at the same time, and it's not simple to do...

Jim

[gmont]

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@jonwang wrote:

I'm just too curious to not ask... what are you doing over WiFi that you need more than 350Mbps?  Anything that wouldn't work just the same if it were 30Mbps or are you just worried about chasing numbers?

I get similar questions from customers all the time.  I'm genuinely curious, not trying to be a punk.

---

I pay for gigabit connection and obviously I want to be able to use it. 

When I download 100 gigs in gbit speed it will take 14 minutes, and on 300 mbit - 50 minutes. 

If your web browsing is about watching youtube and scrolling facebook you do not need high speeds, but I do. 

[gmont]

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@eejimm wrote:

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@jonwang wrote:

Are you aware that those numbers are air rate numbers not actual throughput.  Its sort of like a cable negotiation at 10/100/1000.

---

Right - the "over the air" rate for WiFi is basically double the best actual throughput you will see.   It's a marketing thing the industry started 20 years ago (before Ubiquiti even existed) and everyone has to use it or their printed numbers look bad.   Technically it's about overhead and the actual modulation and error correction protocols used over the air.   Take whatever the published numbers are and cut them in half, basically. 

As to why people want so much over WiFi, we get the  same questions all the time, and it usually is because people want what they think they should get.   The bigger issue is when you get a number of devices on an AP at the same time - WiFi doesn't scale very well.   In tests with very good signals and a very fast AP in 5GHz with no interference but 20 devices all doing "normal" stuff (ie no streaming video etc.) the max speed possible dropped to under 30Mb even though the raw numbers said there should be way more.   It's due to the way WiFi works and how multiple clients all contend for the connection.   We build large hotel and outdoor venues that can handle over 10,000 connections at the same time, and it's not simple to do...

Jim

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Not really. Does overhead and interference rely on CPU Speed? I do not think so, in this situation the problem is in slow cpu. 

100mbit ethernet with utp-5 cable should not be longer than 100 metres - and you can observe significant decrease in speeds with cable from 80 metres already - but that have nothing to do with CPU load. Your CPU will stay at 0% utilization but your speed will not be 100 mbit. 

Same here. If only interference is messing with cpu, than I can accept your arguments. 

[UBNT-JoshMcGee]

In fact, yes, those things may rely on the CPU to process the packets. A similar issue exists in routers with IPS enabled, where the router is capable of gigabit throughput but the overhead of IPS processing can cut that throughput into a third or so.

In part, the problem may be a slow cpu, but again this device is not intended for fiber to the home connections. It's designed for WISP operators to install in customer homes to provide basic and simply managed wireless for the users, budget-priced to meet the budget demand.

[UBNT-SNK]

As Josh has mentioned, this product is targeted to WISP clients. We are updating the datasheet to reflect the wireline throughput.

[gmont]

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@UBNT-SNK wrote:
As Josh has mentioned, this product is targeted to WISP clients. We are updating the datasheet to reflect the wireline throughput.

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 I am happy for your targeting guys, but the thing is that retailers are selling it as Wireless Access Point  

I have no complaints really about it not being able to deliver 866 mbits, I was only asking if the problem is with cpu - maybe there is some bug or future firmware could fix that. For example, my old Asus RT-N56U with 3rd party firmware has now udp/tcp hardware offloading for both wan/lan and therefore cpu load stays near 0 even at gbit download speeds. 

Apparently it is not the case here (or WiFi can not be hardware offloaded?) but I am still happy with AirCube's value for money. 

[UBNT-JoshMcGee]

It is not yet clear to me what the bottleneck comes from, but for the time being we are heavily focused on some other bugfixes.

[MimCom]

ISTR someone posting info on the SoC when these were first released to the EA Store, and that the chip was also availble in a version with hwnat.  This would significantly improve performance for wired clients.

[UBNT-SNK]

We are not currently looking to revise the airCube hardware, but will investigate throughput increases once bug fixes and features are out of the way as Josh mentioned above.