Timing question with 802.11r and OTA roaming.

Jouni Malinen j
Sun Jun 29 01:49:56 PDT 2014

On Tue, Jun 24, 2014 at 11:52:41AM -0700, Ben Greear wrote:
> We are seeing a case where it appears to take around 9ms from the supplicant
> roam request Athenticate until the packet hits the air.  The station is ath9k, APs are cisco.
> After that first Authenticate packet, it seems things go a good bit quicker.

How do you measure this, i.e., which steps are included in that 9 ms?

> Any idea if this is expected behaviour or not?  In particular, I wonder about
> that PTK failure.  We are running software-crypt on the station, in case that
> matters.

PTK failure is cfg80211/mac80211 "feature" (no STA entry for the new AP
yet) and while it takes some time to go through, I don't think it is
significant and anyway, this is after the Authentication frame exchange,
so I'd assume it is not included in that 9 ms.

It should be possible to skip this set_key prior association that is
currently failing with cfg80211/mac80211, but a more appropriate cleanup
could be in adding the STA entry sooner to allow this early PTK
configuration to succeed instead, so that the data connection would be
functional immediately on reassociation.

Jouni Malinen                                            PGP id EFC895FA

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