Re: [RFC V2] cfg80211: introduce critical protocol indication from user-space

[Dan Williams <dcbw@redhat.com>]

On Thu, 2013-03-28 at 23:44 +0100, Johannes Berg wrote:
> On Thu, 2013-03-28 at 17:42 -0500, Dan Williams wrote:
> 
> > > Well, you can do DHCP a second or so, I'd think? And EAPOL much quicker,
> > > of course. I don't really see any reasonable minimum time? We might want
> > > to enforce a max though, maybe.
> > 
> > Not quite.  A lot is dependent on the server itself, and I've had users
> > on university and corporate networks report it sometimes takes 30 to 60
> > seconds for the whole DHCP transaction to complete (DISCOVER, REQUEST,
> > OFFER, ACK).  Sometimes there's a NAK in there if the server doesn't
> > like your lease, which means you need another round-trip.  So in many
> > cases, it's a couple round-trips and each of these packets may or may
> > not get lost in noisy environments.
> 
> Oh, yes, of course. However, we're talking about optimising the good
> cases, not the bad ones. Think of it this way: if it goes fast, we
> shouldn't make it slow by putting things like powersave or similar in
> the way. If it's slow, then it'll still work, just slower. But when
> "slower" only means a few hundred milliseconds, it doesn't matter if
> everything takes forever (30-60 secs)

True, but at least 4 or 5 seconds is the minimum time I'd recommend here
for DHCP.

Dan