Wake Accesspoint over WLAN

Karl Rothenhöfer karl
Tue Mar 1 02:41:58 PST 2011

Hello Johannes,


thank you for your quick and clear reply.


I understand the special interest in waking up clients e.g. for all kinds of
maintenance activities.


And I could also notice, that the interest to wake up the accesspoint itself
by a client being interested in service has not been mentioned publicly.
Nevertheless my interest still persists and a solution for my issue could be
helpful for others as well.


I understand, that in order to be wakeable a client must stay connected with
the accesspoint. The client is evidently able to maintain connectivity using
5Vsb (5V standby voltage). With what I know it seems thinkable that an
accesspoint could also use 5Vsb to continue performing its routine task of
sending beacon frames and providing support for the clients to maintain
connection. If that would be achievable with firmware means only, i.e.
without SW support, then it would also seem thinkable to react on wake up
events, exactly as clients do with the same HW and possibly firmware.
Whether this is true was the fundamental question of my initial mail.


Besides there have been other questions in my initial mail, where answers
would still be desirable and where for sure there are expert participants in
the hostap mailing list who have knowledge and are possibly prepared to give
helpful answers. I take the freedom to repeat them here:


1.    Has ath9k become ready and stable for usage in a Linux based
      (hostap documents say, that madwifi is required, can madwifi be
substituted by ath9k)

2.    What WLAN-Adapters supported by ath9k are available, with capabilities
for WOWLAN (at least for clients)?

3.    Can a WLAN Client wake up its accesspoint over WLAN (see my reasoning

4.    Can wake up be performed with both Magic Packet and Special Pattern
(at least for waking up clients)?


Many thanks again for kind and helpful answers from anybody being
knowledgeable in these topics.









>-----Original Message-----

>From: Johannes Berg [mailto:johannes at sipsolutions.net]

>Sent: Samstag, 26. Februar 2011 11:12

>To: karl at krothenhoefer.de

>Cc: hostap at lists.shmoo.com

>Subject: Re: Wake Accesspoint over WLAN


>On Fri, 2011-02-25 at 22:50 +0100, Karl Rothenh?fer wrote:


>> I want to implement a Wireless server based on Linux. If idle persists

>> for a longer time I would like the server to shutdown to standby in

>> order to save energy; and I would like to wake up the server over wlan

>> (WOWLAN) by clients requesting service.


>WoWLAN typically supports only clients staying connected to an AP while

>suspended and then being woken up.





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