RSN/WPA2 - PMKSA cache in STA and in AP

Jouni Malinen jkmaline
Sun Apr 10 11:00:39 PDT 2005

On Tue, Feb 22, 2005 at 01:40:54PM +0100, Ajeet Nankani wrote:

> If STA roams to other AP and makes a new PMKSA with new AP, then does 
> STA keep previous PMKSAs which it made with previous AP(s), in its 
> cache, if yes for how long and for how many previous APs?

This is implementation specific; wpa_supplicant uses a limit of 32 PMKSA
cache entries and 12 hours lifetime for PMKSA. Some drivers limit the
number of PMKSA cache entries to a smaller number, though.

> Same question on AP side, that for how long AP keeps PMKSA of STAs which 
> associated with it previously but now have been roamed to other APs 
> hence are not currently associated with this old AP.

Implementation specific; hostapd has limit of 1024 PMKSA cache entries
and default lifetime of 12 hours, but this can be overriden with RADIUS
Session-Timeout attribute.

Jouni Malinen                                            PGP id EFC895FA

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