Subject: ifconfig for wireless LAN
To: None <>
From: Atsushi Onoe <>
List: tech-net
Date: 03/07/2000 22:37:27
I'd like to propose the changes of ifconfig media/mediaopt for IEEE802.11
wireless LAN as follows:
	media		{ infrastructure | adhoc }
	mediaopt	[ create-ibss | no-bssid ] [ wep ] [ power-mgmt ]

Comparing with the current usages:
	media		{ FH1 | FH2 | DS1 | DS2 | DS5 | DS11 }
	mediaopt	[ adhoc ]

I think it's not so good at the following points.
	1. "FH" and "DS" cannot be set at all.  It just show the type of
	   PHY chip on the card, and printed at attaching the interface
	   would be enough.

	2. Bit rate is not necessarily specified for most cases.
	   Both for infrastructure mode and ad-hoc (IBSS) mode,
	   spec says that the PHY with multirate support MUST use
	   basic rate for multicast/broadcast and control frames,
	   and MUST NOT transmit at a higher rate without prior knowledge
	   of destination's supported rate, which are shown by beacon
	   frames or association requests.

	   Though only WaveLAN ad-hoc mode may need of fixed rate,
	   auto rate select apparently works on WaveLAN ad-hoc mode.

	3. The infrastructure mode and the ad-hoc mode are clearly different
	   and cannot interoperable each other.  So they cannot be "media
	   options" but mutually exclusive "media types".

And there are some more options to be defined for wireless LAN.
	create-ibss	Create its own IBSS and announce it when it fails
			to find or join existing IBSS.
			Only valid for the adhoc media type.
			Note that isolated two node with this option
			cannot talk to eath other even if they come closer
	no-bssid	Do not use bssid nor beacons at all.  It is just
			same as adhoc mode of WaveLAN (wi(4)).
			Only valid for the adhoc media type.
	wep		Enables WEP (Wired Equivalent Privacy).  It requires
			WEP encryption to communicate others.
	power-mgmt	Enables power management capability.  Only available
			for infrastructure media type and it requires
			additional support by access points.

Possibly more to be defined somewhere:
	desired ESSID	currently can be specified by the "nwid" parameter of
			ifconfig(8).  Empty string ('') means wildcard
			ESSID which allow to connect any access points.
	created ESSID	used for "create-ibss".  It may be the same string
			with desired ESSID but it should not be empty.
	WEP key		used for "wep" encryption/decryption.
	channel/pattern	used for "create-ibss" to determine the radio
			frequency (DS) or hopping pattern (FH) to be used
			to create IBSS.  Also used for "no-bssid".

Though I'm not quite sure whether these parameters should be specified
by ifconfig, I don't hope there are so many XXXconfig commands...

Any comments?

Atsushi Onoe

> > Add ifmedia support so that dhcp happy.  Also, add nwid support.
> Actually, the "ad-hoc" mode of WaveLAN firmware is not the same referred
> as "ad-hoc" or "IBSS" mode in the 802.11 spec.  IBSS in the spec announces
> beacon and uses a bssid in the header to allow overlapping multiple
> segments onto one channel.
> "WaveLAN ad-hoc mode" uses zero'ed bssid only and there are no beacons
> nor state transitions at all.  This is the reason WaveLAN cannot
> interoperate with other 802.11 products in ad-hoc mode.
> Based on these, using "adhoc" mediaopt for wi (WaveLAN) driver is
> a little confusing.  How about "wladhoc" or something like that?
> FYI, I'm rewriting awi driver and I can interconnect WaveLAN ad-hoc
> mode with awi DS cards.
> Atsushi Onoe