[Date Prev][Date Next]   [Thread Prev][Thread Next]   [Thread Index] [Date Index] [Author Index]

Re: WLAN: link must be UP before ESSID is set

On Tue, 2007-02-06 at 22:04 +0200, Pekka Savola wrote:
> Hi,
> On new USB stick WLAN interface (driver zd1211rw) it seems that the 
> 'ip link set $DEVICE up' needs to be done before ESSID is set for the 
> card to come up at all. (On the other hand, for example, the old 
> orinoco_cs doesn't require this.)
> Even though DHCP client (run after ESSID is set) brings up the link, 
> the WLAN card is not associated to the AP (the state as shown below), 
> and IP doesn't work yet.
> zd1211rw people had the opinion that this is a problem with ifup:
> "This is a distro bug - it should bring the interface up before using 
> it. Many drivers require the interface to be up before scanning is 
> possible, since for a lot of hardware, scanning is just transmission 
> and reception of frames so requires the entire MAC layer to be 
> activated just the same as if you were transmitting/receiving data."
> Should this be fixed by setting the link up before setting ESSID in 
> ifup-wireless (or even before setting some other iwconfig options)?

Likely, yes.  The device should be brought up before setting stuff on
it.  Some devices don't load firmware until you bring the device up.

Ideally though, drivers should be caching the settings that userspace
pushes down, and on ifup blasting those settings to firmware.  But many
softmac drivers don't yet do this.


> Is there any drawback in doing so? (At least it seems to me that you 
> may not be able to specify a new MACADDR if this was done.)
> Is there already a bug report on this (based on very quick search I 
> couldn't find one)?
> eth1      IEEE 802.11b/g  ESSID:"S"  Nickname:"zd1211"
>            Mode:Managed  Frequency:2.412 GHz  Access Point: Invalid
>            Bit Rate=1 Mb/s
>            Encryption key:off
>            Link Quality:0  Signal level:0  Noise level:0
>            Rx invalid nwid:0  Rx invalid crypt:0  Rx invalid frag:0
>            Tx excessive retries:0  Invalid misc:0   Missed beacon:0
> -- 
> Pekka Savola                 "You each name yourselves king, yet the
> Netcore Oy                    kingdom bleeds."
> Systems. Networks. Security. -- George R.R. Martin: A Clash of Kings

[Date Prev][Date Next]   [Thread Prev][Thread Next]   [Thread Index] [Date Index] [Author Index]