Does CPU matter for an AP

I'm looking to separate my router and wireless AP hardware. For the router device, CPU clearly matters, but what about for the AP device? When a wi-fi router is put into AP-mode does the switch silicon handle the traffic between the wireless and the wired ports or does the CPU still come into play in some meaningful way?

It matters less, but still matters.

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wireless isn't connected directly to switch controller, so the CPU is only doing bridging, which isn't that heavy. What kills the CPU is the routing, aka the NAT and the firewall between WAN and LAN interfaces. An AP does not do any of this.

imho, for most if not all wifi ac (and lesser) devices with integrated wifi, the onboard CPU is much faster than the wifi itself can ever be. Maybe this changes with Wifi 6, but I kinda doubt it.

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Yes and no, wireless interrupt servicing at high throughput does tax the AP's CPU quite a bit as well (proprietary firmwares can often offload this to some extent, OpenWrt rarely can, as the necessary patches are very invasive). Yes, and AP doesn't also need to cover routing at the same time (which is also very demanding at high WAN speeds), but 'just' wireless uses shouldn't be discarded either.


Thanks @bobafetthotmail and @slh. So the CPU is involved with moving data (or at least orchestrating the DMA?), but it sounds safe to assume any decent router hardware will have plenty of spare cycles if routing is disabled.

For more context: When I started looking at dedicated APs vs routers, the price difference didn't seem very significant. I'm considering getting a router and putting in in AP mode (with OEM firmware) so that in the event my dedicated router does fail, I'll at least have some backup hardware on-hand on which I could deploy OpenWRT and use as a temporary fallback router. So, comparing two router boxes that are more or less identical except for CPU speed, for my case I can go with the lower-cost, slower CPU, option.

Since ebtables firewall rules are needed on the AP for client isolation between 2.4GHz and 5GHz with same SSID, I would guess that will tax the CPU a bit.

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