Subject: Re: [PATCH 00/13] o11s: mesh interface support for mac80211
From: Johannes Berg <johannes@sipsolutions.net>
To: Luis Carlos Cobo <luisca@cozybit.com>
Cc: linux-wireless@vger.kernel.org
In-Reply-To: <47a78212.15588c0a.27b2.61d2@mx.google.com> (sfid-20080204_212233_169667_739F231D)
References: <47a78212.15588c0a.27b2.61d2@mx.google.com>
	 (sfid-20080204_212233_169667_739F231D)
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Date: Thu, 07 Feb 2008 01:13:08 +0100
Message-Id: <1202343188.9965.41.camel@johannes.berg> (sfid-20080207_103527_147888_7C38C7A2)
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Cool stuff! Code looks pretty good but there seems to be some
misunderstanding, especially wrt. beaconing.

> - Possible integration between mesh peer link and sta_info structures. Th=
eir
>   purpose is similar and it will make it easier to implement mesh rate co=
ntrol
>   and airtime link metric.

Indeed, I think this should be done. For one, we already look up the TA
sta_info structure for each frame so you don't need to look it up if you
pass it appropriately. Also a second hash table based on TA address just
takes up a lot of space.

> - Beaconing support: the current beacon model is appropriate for the zd12=
11rw
>   driver but might not be for others.

Indeed. You shouldn't set conf->beacon directly, instead you should
change ieee80211_beacon_get() to support getting an IBSS beacon and then
you need to call ieee80211_if_config_beacon() where appropriate. Using
IEEE80211_HW_HOST_GEN_BEACON_TEMPLATE from the stack is simply wrong
too.

> - set_mesh_cfg command to set mesh ID and use of broadcast mesh ID when n=
one is
>   set: Johannes suggested the mesh ID should be specified when creating t=
he mesh
>   interface [1]. However we feel that a "mesh configuration" or "mesh net=
work"
>   object analogous to the "association" object he talks about would be mo=
re
>   appropriate. Such an association object has not yet been implemented. W=
e
>   would appreciate some advice on how to implement our mesh network objec=
t so
>   that it follows the spirit of mac80211.

Is it really useful to change the mesh ID on a running interface? It
seems that would totally throw off things like multicast caching and
peer link establishment. Therefore, it seems that
ieee80211_if_set_mesh_cfg should reject to configure a running
interface.

> - Scan support: we were waiting for scan to be moved to cfg80211 to avoid
>   messing unnecessarily with wext, is there any effort in this direction?

What specifically do you need? Scanning for mesh networks? Wouldn't a
regular scan find them as well? As far as I know nobody is currently
working on scan support in nl80211. Maybe you can simply report the
relevant mesh IEs in a custom element and sort it out in userspace (for
now)?

johannes

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