Repeater Bridge Mode with ar9170?

Repeater Bridge Mode with ar9170?

[Jon Loeliger]

Folks,

I would like to set up a so-called "wireless repeater bridge mode"
using an ar9170 interface and a wired ethernet interface.  I see
that there is some support for this mode on the DD-WRT, but I was
wondering if it is supported/available with the ar9170 driver.

If it is not already supported, can anyone point me in the right
direction to help get it implemented?

Thanks,
jdl

Re: Repeater Bridge Mode with ar9170?

[Jon Loeliger]

On Wed, 2009-06-24 at 11:33 -0500, Jon Loeliger wrote:
> Folks,
> 
> I would like to set up a so-called "wireless repeater bridge mode"
> using an ar9170 interface and a wired ethernet interface.  I see
> that there is some support for this mode on the DD-WRT, but I was
> wondering if it is supported/available with the ar9170 driver.
> 
> If it is not already supported, can anyone point me in the right
> direction to help get it implemented?
> 
> Thanks,
> jdl

OK, so, in the other (non-mac80211) drivers, there was a mode
called IW_MODE_REPEATER that implemented 4-address framing for
clients that provided the bridging ability.

That same functionality is currently not implemented in the
mac80211 code (ie, no NL80211_IFTYPE_REPEATER mode).

My perhaps mistaken understanding of what it would take to
make this work would be to create a new NL80211_IFTYPE_REPEATER
mode that was a hybrid between _STATION and _WDS modes.  In
particular, it would act like _STATION as far as association
and authentication are concerned, but would also have _WDS-like
4-address frame handling.

Does that seem about right to you guys?  Are folks opposed to
or willing to accept development down those lines?  Or has
anyone already done such work and is willing to share?

Thanks,
jdl

Re: Repeater Bridge Mode with ar9170?

[Johannes Berg]

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On Wed, 2009-06-24 at 17:08 -0500, Jon Loeliger wrote:

> OK, so, in the other (non-mac80211) drivers, there was a mode
> called IW_MODE_REPEATER that implemented 4-address framing for
> clients that provided the bridging ability.
> 
> That same functionality is currently not implemented in the
> mac80211 code (ie, no NL80211_IFTYPE_REPEATER mode).

Actually, the IW_MODE_REPEATER was never quite clearly defined afaict
and we made it WDS instead.

> My perhaps mistaken understanding of what it would take to
> make this work would be to create a new NL80211_IFTYPE_REPEATER
> mode that was a hybrid between _STATION and _WDS modes.  In
> particular, it would act like _STATION as far as association
> and authentication are concerned, but would also have _WDS-like
> 4-address frame handling.
> 
> Does that seem about right to you guys?  Are folks opposed to
> or willing to accept development down those lines?  Or has
> anyone already done such work and is willing to share?

That seems acceptable, though I don't necessarily see a need for adding
a new mode since you can very easily detect that you need to use 4addr
frames, and then it is up to the AP whether to accept them or not.

As far as the AP is concerned, it would probably be violating 802.1X to
accept such frames. Thus, it seems like some fairly obscure
functionality you would only want to enable with a Kconfig option even
on the client side?

johannes

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Re: Repeater Bridge Mode with ar9170?

[Jon Loeliger]

On Mon, 2009-06-29 at 14:25 +0200, Johannes Berg wrote:
> On Wed, 2009-06-24 at 17:08 -0500, Jon Loeliger wrote:
> 
> > OK, so, in the other (non-mac80211) drivers, there was a mode
> > called IW_MODE_REPEATER that implemented 4-address framing for
> > clients that provided the bridging ability.
> > 
> > That same functionality is currently not implemented in the
> > mac80211 code (ie, no NL80211_IFTYPE_REPEATER mode).
> 
> Actually, the IW_MODE_REPEATER was never quite clearly defined afaict
> and we made it WDS instead.

I think WDS is an "AP variant" whereas I'm looking for
a "client variant".

> > My perhaps mistaken understanding of what it would take to
> > make this work would be to create a new NL80211_IFTYPE_REPEATER
> > mode that was a hybrid between _STATION and _WDS modes.  In
> > particular, it would act like _STATION as far as association
> > and authentication are concerned, but would also have _WDS-like
> > 4-address frame handling.
> > 
> That seems acceptable, though I don't necessarily see a need for adding
> a new mode since you can very easily detect that you need to use 4addr
> frames, and then it is up to the AP whether to accept them or not.
> 
> As far as the AP is concerned, it would probably be violating 802.1X to
> accept such frames. Thus, it seems like some fairly obscure
> functionality you would only want to enable with a Kconfig option even
> on the client side?

I think I need to do this strictly from a client/station perspective.
The only AP in this picture would be the "upstream" AP to which my
client is associated.  We shouldn't be changing any code running on
those APs at all.

Which leads to me trying to figure out how the client is able to
know what the correct "MAC level NAT address" needs to be to
when it converts the 802.11 header to the 802.3 header.  Doesn't
the upstream AP have to have already sent you 4-address frames
for this to work?  Or will it respond with a 4-address frame if
it is sent a 4-address frame from the station?

> johannes

Thanks,
jdl

Re: Repeater Bridge Mode with ar9170?

[Johannes Berg]

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On Mon, 2009-06-29 at 10:39 -0500, Jon Loeliger wrote:

> I think I need to do this strictly from a client/station perspective.
> The only AP in this picture would be the "upstream" AP to which my
> client is associated.  We shouldn't be changing any code running on
> those APs at all.

Right. Still though, an AP implementing it wouldn't seem to be
compliant, so I would have guessed that APs don't implement this.

> Which leads to me trying to figure out how the client is able to
> know what the correct "MAC level NAT address" needs to be to
> when it converts the 802.11 header to the 802.3 header.  Doesn't
> the upstream AP have to have already sent you 4-address frames
> for this to work?  Or will it respond with a 4-address frame if
> it is sent a 4-address frame from the station?

No idea. Nothing of this is specified in 802.11 or anywhere else, so
it's all implementation dependent hacks.

johannes

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