80211s with DFS

80211s with DFS

[Volker von Hoesslin @ SKBX Systems]

hi mailinglist!

i have a real big problem! i'm trying to implement a wireless-mesh 
(80211s) with openWRT (current trunk) over 11a (5GHz) with "authSAE" for 
outdoor. all works fine, mesh is runnning and all fine. but now, i'm at 
germany and for the outdoor use, i have to use the channel 100-140 with 
DFS & TPC. so the mesh implementation dont work in this channel? with 
this error:

authSAE config:
#######################################################
authsae:
{
  sae:
   {
     debug = 480;
     password = "foobar";
     group = [19, 26, 21, 25, 20];
     blacklist = 5;
     thresh = 5;
     lifetime = 3600;
   };
  meshd:
   {
     meshid = "foobar";
     interface = "mesh0";
     band = "11a";
     channel = 104;
     htmode = "ht20";
     mcast-rate = 6;
     debug = 1;
   };
};
#######################################################

starting mesh with "authSAE":

#######################################################
# meshd-nl80211 -c /etc/authsae.cfg
----------
nlcfg rates hexdump
00 3c 00 5a 00 78 00 b4 00 f0 01 68 01 e0 02 1c
----------

----------
mgtk:  hexdump
ce 5a b3 fc 8b 76 db 62 11 c9 58 33 fa 0c 26 88
----------

----------
Fixed Information Elements in this STA hexdump
01 08 8c 12 98 24 b0 48 60 6c
----------

meshd: Starting mesh with mesh id = foobar
----------
basic rates: hexdump
8c 98 b0
----------

joining mesh foobar on freq 3443784, mode 0
nlerror, cmd 68, seq 1376254403: Invalid argument
#######################################################

and this is without "authSAE":

#######################################################
# iw mesh0 set channel 104
# iw mesh0 mesh join foobar
command failed: Invalid argument (-22)
#######################################################

but this is working with a non-DFS channel 44:

#######################################################
# iw mesh0 set channel 44
# iw mesh0 mesh join hackewrt
[21044.240000] IPv6: ADDRCONF(NETDEV_CHANGE): mesh0: link becomes ready
[21044.240000] mesh-br: port 1(vlan11) entered forwarding state
[21044.250000] mesh-br: port 1(vlan11) entered forwarding state
[21044.260000] IPv6: ADDRCONF(NETDEV_CHANGE): vlan11: link becomes ready
[21044.260000] coova-br: port 1(vlan12) entered forwarding state
[21044.270000] coova-br: port 1(vlan12) entered forwarding state
[21044.280000] IPv6: ADDRCONF(NETDEV_CHANGE): vlan12: link becomes ready
root@6470028F55A2:~#

#######################################################


i think this error is from the "netlink lib(libnl genl)"...

if i use a channel without DFS, it works fine (in germany channel like 
36-48)... so how it is possible to use mesh (80211s) with DFS ?

big thx for answer,
   volker...

Re: 80211s with DFS

[Simon Wunderlich]

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On Sun, Aug 11, 2013 at 11:03:38PM +0200, Volker von Hoesslin @ SKBX Systems wrote:
> i think this error is from the "netlink lib(libnl genl)"...
> 
> if i use a channel without DFS, it works fine (in germany channel
> like 36-48)... so how it is possible to use mesh (80211s) with DFS ?

mac80211 does not support DFS in mesh mode so far, the only DFS
support implemented is AP mode (and only with ath9k compatible chips).
I'm currently working on IBSS, I don't if/who will work on
802.11s DFS ...

Cheers,
	Simon

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Re: 80211s with DFS

[Volker von Hoesslin @ SKBX Systems]

> I'm currently working on IBSS, I don't if/who will work on
> 802.11s DFS ...
>

it is possible to speed up this work? maybe pay for it!

RE: 80211s with DFS

[Wright, Brett]

> -----Original Message-----
> From: linux-wireless-owner@vger.kernel.org [mailto:linux-wireless-
> owner@vger.kernel.org] On Behalf Of Volker von Hoesslin @ SKBX Systems

> i have a real big problem! i'm trying to implement a wireless-mesh
> (80211s) with openWRT (current trunk) over 11a (5GHz) with "authSAE"
for
> outdoor. all works fine, mesh is runnning and all fine. but now, i'm
at
> germany and for the outdoor use, i have to use the channel 100-140
with DFS
> & TPC. so the mesh implementation dont work in this channel? with this
> error:
> 

Hi 

The real difficulty with DFS and 802.11s is what happens when a radar is
detected? All mesh nodes need to be on the same channel, so there needs
to be some consistent way of propagating a channel switch announcement
to all wireless nodes. 

Brett

Re: 80211s with DFS

[Volker von Hoesslin @ SKBX Systems]

> The real difficulty with DFS and 802.11s is what happens when a radar is
> detected? All mesh nodes need to be on the same channel, so there needs
> to be some consistent way of propagating a channel switch announcement
> to all wireless nodes.
>

indeed, thats a hard question. my first hint is looking at cisco 
(http://www.cisco.com/en/US/docs/wireless/technology/mesh/7.0/design/guide/MeshAP_70.pdf 
-> page 169), but 80211s has't a RAP so maybe there are only some tips 
for a workflow.

i think there are diffrent possibilities:

1. the MAP that has a radar detection go sleep and wait till the channel 
is clear to come back -> mesh will down :/
2. the mesh has to negotiate a new free channel via bacon-frames, maybe 
generating preventively a list of  channel for switching?
3. some other ideas ?

is there someone at work for a DFS implementation?

volker...