Maybe my feeble brain was remembering 20k PPS as 20 Mbps. Like you say, those numbers make sense. And it tells me a quick fix worth trying is to just crank the existing 450 AP up to a 30 MHz channel and gain up to 50%.
From: AF <af-boun...@af.afmug.com> On Behalf Of Adam Moffett Sent: Friday, October 23, 2020 9:59 AM To: af@af.afmug.com Subject: Re: [AFMUG] [ External ] Re: 450 and 450i AP CPU limit on throughput? 20k PPS * 353Byte average iMix packets = 56,480,000 bits. That jives. On 10/23/2020 9:32 AM, Matt Mangriotis via AF wrote: The original 450 AP and SM were roughly the same PPS, and had similar limits. the AP having more FPGA gates, it has some additional resources to handle more things. In practice, in a typical network with mixed packet sizes, this ends up around 55-60 Mbps in a 20 MHz channel (PPS did improve over time going from 13k when they were first released, to ~20k these days. but we reached the limit of what those chips could do). The good news is that 450i, 450b and the new MicroPoP radios are all built using a next generation FPGA (SoC), which has embedded ARM processors, and with Release 20, we've unlocked some serious gains in PPS on these bad boys. effectively increasing PPS by 250% or more (from ~40k to >100k). If it's a budget-constrained site, I might suggest a MicroPoP as an upgrade, depending on how many SMs you need to serve (and how far away they are). Standards-based chipsets have a distinct advantage in this area because the MAC/PHY is baked into the ASIC chip and does what it does very well. but limits the flexibility on what can be done. With our current approach, nearly anything is possible given time and resources, because everything down to Layer 1 is coded into that FPGA. but it adds a bit of cost. Matt From: AF <mailto:af-boun...@af.afmug.com> <af-boun...@af.afmug.com> On Behalf Of Ken Hohhof Sent: Friday, October 23, 2020 8:21 AM To: 'AnimalFarm Microwave Users Group' <mailto:af@af.afmug.com> <af@af.afmug.com> Subject: [ External ] Re: [AFMUG] 450 and 450i AP CPU limit on throughput? Not talking about sustained speed keys (finally gone in the 450b) but the point at which you haven't maxed out the RF capability but the CPU horsepower becomes the limiting factor and you can't get any more pps through it. I think the SMs also have this issue, but less likely to be a problem unless using them in PTP mode or having a small number of very high bandwidth customers. Or maybe you are saying the APs never had the CPU limitation like the SMs, but I'm pretty sure they did. Each generation 450, 450i, 450m having a more powerful CPU. Although not as powerful as we might think from the price, I guess maybe the result of using a processor core in an FPGA, it seems like lowly WiFi chips have more CPU power. I think most of us were surprised to find the limitation could be CPU not RF. From: AF <af-boun...@af.afmug.com <mailto:af-boun...@af.afmug.com> > On Behalf Of Adam Moffett Sent: Friday, October 23, 2020 6:42 AM To: af@af.afmug.com <mailto:af@af.afmug.com> Subject: Re: [AFMUG] 450 and 450i AP CPU limit on throughput? I thought the limitation was on what a single SM did. .....maybe mistaken. On 10/23/2020 12:14 AM, Ken Hohhof wrote: Does anyone know off the top of your head what the current CPU limited max throughput is for 450 vs 450i APs? Not based on RF characteristics but packet processing in the CPU. I keep thinking at one time 450 APs were only capable of maybe 20 Mbps but that can't be right because I have some doing over 40. I think Cambium said that firmware tweaking kept raising that number. I'm asking because I have one lone site with a 450 and an omni, and maybe a dozen subs scattered through the entire 360 degrees. So while I am going to need more throughput, it just doesn't justify 4 sectors, and the cables are in conduit and I think we only ran 4 cables and we have 2 backhauls. And it occurs to me what I need isn't sectors, it's to increase the channel width to 30 MHz (450) or 40 MHz (450i). But will a 30 MHz channel really help if the 450 AP is pps limited by the CPU? I'm OK with replacing the 450 with a 450i if necessary. Most sites we have at least 4 sectors, so mostly 20 MHz channels. But an omni with a 40 MHz channel would use the same amount of spectrum as 4 sectors and 20 MHz channels.
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