Date: Sun, 18 Aug 2002 10:57:28 +0100 (BST) From: Duncan Barclay <dmlb@dmlb.org> To: "M. Warner Losh" <imp@bsdimp.com> Cc: mobile@FreeBSD.ORG, eyurtese@turkuamk.fi Subject: Re: IBSS and BSS with multiple FreeBSD Wireless Gateways Message-ID: <XFMail.20020818105728.dmlb@computer.my.domain> In-Reply-To: <20020817.154929.130696556.imp@bsdimp.com>
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On 17-Aug-2002 M. Warner Losh wrote: > In message: > <Pine.A41.4.10.10208171330130.4338-100000@bessel.tekniikka.turkuamk.fi> > Evren Yurtesen <eyurtese@turkuamk.fi> writes: >: Is it possible to use FreeBSD with IBSS or BSS mode as a bridge to >: overcome line of sight issues? and provide roaming for mobile users? For 802.11 specified roaming to work, you need to be in BSS mode and set up an ESS - extended service set. The APs all need to talk to each other so that the _single_ gateway to the rest of the internet knows where to send packets. Traditionally this was done with a propiertry protocol, but there is now a standard way of doing this- 802.11d I think. >: Another question is if we are using IBSS mode and 2 clients are close >: to each other but the gateway is little bit more far away. Does it cause >: the clients to choose each other instead of the gateway because they >: have stronger signal? If this happens, wouldnt this cause the link to >: the gateway be broken? > > IBSS mode causes people to try to talk directly to each other as much > as possible. I don't know what the relaying rules for ibss are, but > if you need to rely on a man in the middle, then you are likely going > to be frustrated. I've never tried it, so maybe it just works, but I > kinda doubt it. Grab, read and understand the 802.11 spec :-) IBSS does not have relaying. An IBSS can be simply viewed as wireless Ethernet. I.e. direct peer to peer connections with stations communicating directly with each other. If an IP packet is destined to go the the outside world, the packet is sent directly to the gateway machine - this isn't 802.11, but IP routing. The reason IBSS does not have relaying, and the reason that all station to station traffic in an BSS goes via the AP is basically the same. It is a lot easier to implement roaming and relaying in wireless systems, when there are defined network entities such as a basestation, i.e. and AP. Some people have played with relaying in IBSS but it requires changes to the protocol stack within the cards. Duncan -- ________________________________________________________________________ Duncan Barclay | God smiles upon the little children, dmlb@dmlb.org | the alcoholics, and the permanently stoned. dmlb@freebsd.org| Steven King To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-mobile" in the body of the message
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