On Wed, Dec 24, 2014 at 09:15:03PM +0100, Christian Weisgerber wrote:
> Jonathan Thornburg:
>
> > > I have no experience with that configuration, but I had a broadly
> > > comparable setup where a Soekris net5501 (same CPU as the ALIX) did
> > > IPsec for a .11g network.
> >
> > What was the bandwidth of that network?
>
> .11g, "54 Mbit/s". Something like 2 Mbyte/s throughput into the
> wired network.
Generally, it makes no sense to expect the maximum wifi throughput as
a matter of course. You'll see it under optimal conditions which depend
on a lot of factors. Most of the time a lower rate will be used to prevent
excessive packet loss and retransmits. This is a balancing act.
Our net80211 stack selects the rate using AMRR ("Adaptive Multi Rate Retry").
Our implementation of AMRR describes itself as "naive", which probably
means it's not optimised much. It also differs from what many other OSs do.
ifconfig output indicates the currently selected data rate, e.g. mine has
currently settled at 18Mbit/s:
media: IEEE802.11 autoselect (OFDM18 mode 11g)
Data transmit rate selection happens at both ends of the wifi link independently
and can vary for each individual frame. The transmission rate for the data part
of a frame is announced in the frame header (the header is usually transmitted
at fixed 1MBit/s).
Some 11n devices have more tricks up their sleeves (e.g. beam forming) but
OpenBSD doesn't support any of those.
