Simple questions (RID, fragmentation, handover)

Jouni Malinen jkmaline at
Sat Dec 21 21:45:23 EST 2002

On Sat, Dec 21, 2002 at 11:57:11PM +0900, yamada kenta wrote:

> What's RID ? I think it Resource IDentifier. 
> And if RID is Resource IDentifier what's this?

Yes, it is resource identifier and it is a data element that is used to
configure Prism2 card and to read configuration related information from
the card.

> When Packet size is larger than 802.11x frame size , packet is
> fragmented. Is this fragmentation processed by firmware or HostAP driver ?

There is no 802.11x, but I'm assuming you are talking about 802.11
fragmentation. First of all, this framentation is mainly used to make
sent frames smaller to reduce probability of errors, so it does not
generally increase the packet size. Anyway, 802.11 fragmentation and
reassembly is performed by firmware, except when host-based WEP
decryption is used. Since 802.11 encrypts each fragment separately, Host
AP driver takes care of reassembly when host_decrypt is configured.

> How to select APs when handover happend ? 
> and Is this event processed by firmware or HostAP driver ?

That is implementation specific issue. Usually station selects the best
available AP when the signal quality of the current AP drops below some
threshold value. In default Managed mode, firmware takes care of this.
However, Host AP driver has support for host-based roaming (prism2_param
wlan0 host_roaming 1), in which Host AP driver does this AP selection
(although, current implementation depends on firmware doing the scanning
and noticing when signal quality drops).

Jouni Malinen                                            PGP id EFC895FA

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