[Make-wifi-fast] [bbr-dev] Aggregating without bloating - hard times for tcp and wifi

[Bob McMahon]

Some main purposes of the WiFi CPU is 802.3 to 802.11 L2 translational
bridging and handling 802.11 protocols for things like association. Most
forwarded packets don't hit the main CPU anymore. This first sw to hw
transition occurred decades ago with real internet routers (equipment that
run IGPs and BGP) which started as software in the early 90s and then moved
to hardware. The same engineering has been happening for home gateways or
WiFi APs bridging wired to wireless.

Bob

On Tue, Nov 22, 2022 at 12:16 PM David Lang <david at lang.hm> wrote:

> sorry, when I was saying 'the cpu', I was meaning the main one running
> linux,
> not something that's part of the wifi chipset.
>
> I would be very surprised if the wifi chipset is doing any packet routing,
> as
> opposed to just sending the packets to the main processor.
>
> Remember, the common case isn't forwarding from one wifi device to
> another, it's
> moving between wifi devices and the wired uplink.
>
> David Lang
>
> On Tue, 22 Nov 2022, Bob McMahon wrote:
>
> > An AP's radio complex may have a CPU but that doesn't mean it is the
> > standard linux stack as most think of it. Many consider this as part of
> > "firmware" which can be Linux, a Linux derivative or other.  Also, there
> > are some levels of wired/wireless forwarding plane integration done at
> the
> > hardware level that many might be surprised by.
> >
> > Bob
> >
> > On Tue, Nov 22, 2022 at 12:03 PM David Lang <david at lang.hm> wrote:
> >
> >> On Tue, 22 Nov 2022, Bob McMahon via Make-wifi-fast wrote:
> >>
> >>> Finally, many (most?) APs are forwarding and feeding packets at at the
> >>> hardware level so not sure that the linux stack matters as much for an
> AP
> >>> based analysis, particularly when considering multi user transmissions,
> >>> i.e. multiple WiFi clients are active and sharing TXOPs.
> >>
> >> APs forward packets within the switch at the hardware level, but the
> >> radios have
> >> to go through the CPU, so any wired <-> wireless needs to go through the
> >> CPU,
> >> and I would be incredibly surprised if the wifi chips did wireless <->
> >> wireless
> >> routing at the hardware level.
> >>
> >> David Lang
> >>
> >
> >
>

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