Ordering in hostapd

Jouni Malinen j
Fri Jan 30 12:17:17 PST 2009

On Wed, Jan 28, 2009 at 11:03:18AM +0200, Andy Johnson wrote:

>   I just wondered : does hostapd handle ordering?

Ordering of what?

> To be more specific: every frame (data, control and mgmt) should be ACKED.
> Suppose that a first packet received in the AP is not ACKED, it should
> be retransmitted, as we all know.
> Suppose that a second packet is received in the AP before the first
> retransmission is received in
> the AP.
> Does the AP handles a correct ordering ? or is it done inside the
> mac80211 kernel stack?

This has nothing to do with hostapd. If the sender is transmitting
another frame before the first one has been ACKed and then transmits the
initial frame again, it is not following the spec.. It is up to the
transmitter to enforce ordering in this case (as long as we are not
talking about things like block ack).

> ( I appreciate if anybody will tell me where it is done in code, if at
> all; grepping for "reorder"
> gave nothing)

There is no such functionality for standard ACK, so you won't find its
implementation either ;-). Block ACK reordering is in mac80211 (or
driver code, or firmware).

Jouni Malinen                                            PGP id EFC895FA

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