[Prism54-users] Default channel is unsupported?
Aurelien
slts@free.fr
Wed, 12 Nov 2003 18:27:35 +0100
After some investigations it seems that the card uses the right channel num=
bering. But when we ask it to list them it reports em in a strange order. I=
'm gonna address this right now.
=09
ajfa
...And justice for all
On Tue, 11 Nov 2003 14:58:33 +0100
Bj=F8rn Mork <bjorn@mork.no> wrote:
> First let me say thay I'm really impressed by the speed the driver is
> currently improving. Thanks for all the hard work. Let's hope the
> licensing issue is resolved soon.
>=20
> I have been using a SMC2802W as an accesspoint with the old (islpci)
> version of the driver for a while. This works fine as long as I run
> 'setoid eth1 17000019 long 5'. I thought that was needed because the
> client is 802.11b only, but experimenting with the newer driver from
> CVS makes me suspect that the real reason is a bad choice of default
> channel.
>=20
> Note that I don't know anything about how the card/driver do scanning
> in different modes, so my observations may be based on totally wrong
> assumptions.
>=20
> This is what I have noticed: After loading prism54 with all settings
> (both compile time and run time) set to default, I get a client
> scanning all the 2.4 GHz channels for an accesspoint, as expected:
>=20
> canardo:/home/bjorn# /usr/local/src/wireless_tools.26/iwconfig eth1
> eth1 PRISM Duette Mode:Managed Frequency:2.427GHz =20
> Access Point: 00:00:00:00:00:00 Bit Rate:0kb/s Sensitivity=
=3D20/200 =20
> Retry min limit:8 RTS thr:2347 B Fragment thr:2346 B =20
> Encryption key:off
> Link Quality:0 Signal level:0 Noise level:235
> Rx invalid nwid:0 Rx invalid crypt:0 Rx invalid frag:0
> Tx excessive retries:0 Invalid misc:0 Missed beacon:0
>=20
>=20
> But I notice that the list of supported frequencies also include the=20
> 5.15 - 5.35 GHz band:
>=20
> canardo:/home/bjorn# /usr/local/src/wireless_tools.26/iwlist eth1 freq
> eth1 26 channels in total; available frequencies :
> Channel 00 : 5.17 GHz
> Channel 01 : 5.18 GHz
> Channel 02 : 5.19 GHz
> Channel 03 : 5.2 GHz
> Channel 04 : 5.21 GHz
> Channel 05 : 5.22 GHz
> Channel 06 : 5.23 GHz
> Channel 07 : 5.24 GHz
> Channel 08 : 5.26 GHz
> Channel 09 : 5.28 GHz
> Channel 10 : 5.3 GHz
> Channel 11 : 5.32 GHz
> Channel 12 : 2.412 GHz
> Channel 13 : 2.417 GHz
> Channel 14 : 2.422 GHz
> Channel 15 : 2.427 GHz
> Channel 16 : 2.432 GHz
> Channel 17 : 2.437 GHz
> Channel 18 : 2.442 GHz
> Channel 19 : 2.447 GHz
> Channel 20 : 2.452 GHz
> Channel 21 : 2.457 GHz
> Channel 22 : 2.462 GHz
> Channel 23 : 2.467 GHz
> Channel 24 : 2.472 GHz
> Channel 25 : 2.484 GHz
> Current Frequency:2.432GHz (channel 16)
>=20
> A comment in isl_ioctl.c explains why:
>=20
> /* Request the device for the supported frequencies
> * not really revelant since some devices will report the 5 GHz b=
and
> * frequencies even if they don't support them.
> */
>=20
> I also notice that the channels are enumerated with the 5 GHz band
> listed first, and that this makes channel numbers rather meaningless.
> More specifically, these channel numbers are in no way related to the
> 802.11a/b channel numbering.
>=20
> But no real problem so far.
>=20
> The problems start when I change to master mode, which makes the
> driver change to channel 03 (why? the default is supposed to be 6?)
> according to the above enumeration, i.e. 5.2 GHz (channel 40 according
> to 802.11a). That doesn't make much sense with a 802.11g card...
>=20
> canardo:/home/bjorn# /usr/local/src/wireless_tools.26/iwconfig eth1 =20
> eth1 PRISM Duette ESSID:"default" =20
> Mode:Master Frequency:5.2GHz Access Point: 00:04:E2:64:53:A0 =
=20
> Bit Rate:54Mb/s Sensitivity=3D20/200 =20
> Retry min limit:8 RTS thr:2347 B Fragment thr:2346 B =20
> Encryption key:off
> Link Quality:192 Signal level:0 Noise level:64
> Rx invalid nwid:0 Rx invalid crypt:0 Rx invalid frag:0
> Tx excessive retries:0 Invalid misc:0 Missed beacon:0
>=20
> Naturally, I can't get any client to connect at this point. Well,
> 802.11b clients at least - I don't really have any 802.11a clients to
> test with.
>=20
> But if I try setting the channel, then suddenly the driver (or
> iwconfig? I'm a bit confused here) uses 802.11b channel numbers=20
> (ch 5 =3D> 2432 MHz):
>=20
> canardo:/home/bjorn# /usr/local/src/wireless_tools.26/iwconfig eth1 chann=
el 5
> canardo:/home/bjorn# /usr/local/src/wireless_tools.26/iwconfig eth1=20
> eth1 PRISM Duette ESSID:"default" =20
> Mode:Master Frequency:2.432GHz Access Point: 00:04:E2:64:53:A=
0 =20
> Bit Rate:54Mb/s Sensitivity=3D20/200 =20
> Retry min limit:8 RTS thr:2347 B Fragment thr:2346 B =20
> Encryption key:off
> Link Quality:31 Signal level:0 Noise level:225
> Rx invalid nwid:0 Rx invalid crypt:0 Rx invalid frag:0
> Tx excessive retries:0 Invalid misc:0 Missed beacon:0
>=20
>=20
> But still not when listing the available channels. Note the channel
> number listed after "Current Frequency":
>=20
> canardo:/home/bjorn# /usr/local/src/wireless_tools.26/iwlist eth1 freq
> eth1 26 channels in total; available frequencies :
> Channel 00 : 5.17 GHz
> Channel 01 : 5.18 GHz
> Channel 02 : 5.19 GHz
> Channel 03 : 5.2 GHz
> Channel 04 : 5.21 GHz
> Channel 05 : 5.22 GHz
> Channel 06 : 5.23 GHz
> Channel 07 : 5.24 GHz
> Channel 08 : 5.26 GHz
> Channel 09 : 5.28 GHz
> Channel 10 : 5.3 GHz
> Channel 11 : 5.32 GHz
> Channel 12 : 2.412 GHz
> Channel 13 : 2.417 GHz
> Channel 14 : 2.422 GHz
> Channel 15 : 2.427 GHz
> Channel 16 : 2.432 GHz
> Channel 17 : 2.437 GHz
> Channel 18 : 2.442 GHz
> Channel 19 : 2.447 GHz
> Channel 20 : 2.452 GHz
> Channel 21 : 2.457 GHz
> Channel 22 : 2.462 GHz
> Channel 23 : 2.467 GHz
> Channel 24 : 2.472 GHz
> Channel 25 : 2.484 GHz
> Current Frequency:2.432GHz (channel 16)
>=20
> However, at this point things seem to be working. iwconfig interpretes
> channels 1 - 14 as they are specificed in 802.11b and refuses to set
> channel 0 or 15 - 25. But the card can still be set to a nonworking
> mode by specifiying 802.11a channels:
>=20
> canardo:/home/bjorn# /usr/local/src/wireless_tools.26/iwconfig eth1 chann=
el 36
> canardo:/home/bjorn# /usr/local/src/wireless_tools.26/iwconfig eth1=20
> eth1 PRISM Duette ESSID:"default" =20
> Mode:Master Frequency:5.18GHz Access Point: 00:04:E2:64:53:A0=
=20
> Bit Rate:54Mb/s Sensitivity=3D20/200 =20
> Retry min limit:8 RTS thr:2347 B Fragment thr:2346 B =20
> Encryption key:off
> Link Quality:190 Signal level:0 Noise level:66
> Rx invalid nwid:0 Rx invalid crypt:0 Rx invalid frag:0
> Tx excessive retries:0 Invalid misc:0 Missed beacon:0
>=20
>=20
> So my question is: Can iwlist list the standard 802.11a/b channel
> numbers as expected by iwconfig? And more important: Is there some
> way to ensure that a working channel is used by default? Why do I end
> ut with channel 40 as default on a 802.11g card?
>=20
>=20
> Bj=F8rn
>=20
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>=20