[Olsr-users] Problem with establishing robust relaying in OLSRD
Denia Bouhired
(spam-protected)
Thu Oct 27 10:46:51 CEST 2011
Hello Markus,
Thank you for your advice, and sorry for the belated reply as we are at
our wits-end trying to debug this problem.
Actually you were right it seems it has nothing to do with OLSRD, as the
link seems to have the same behaviour without olsrd runnning.
Also note that in the original long description, the effect didn't seem
to be symmetrical, so basically if A is taken away from the network, the
same effect would not be seen between C and B.
We think it has something to do with the WiFi dongles we're using which
have a WPS (Wifi Protected Setup) capability, which may (or may not) be
causing the problem.I know WPS isn't supposed to be active in adhoc
mode, but it seems like somehow the driver is setting one dongle as a
master (AP like device) without which the network seems to fall apart,
the network is re-established when it comes nearer again.
Have you got any ideas about this (although I know it's outside the
scope of this mailing list)?
Many thanks and regards,
Denia
On 10/24/2011 03:42 PM, Markus Kittenberger wrote:
> arping -c 10 -b -I eth1 193.238.156.158
> ARPING to 193.238.156.158 from 193.238.159.57 via eth1
> Unicast reply from 193.238.156.158 [0:15:6d:8a:ef:c9] 3.530ms
> Unicast reply from 193.238.156.158 [0:15:6d:8a:ef:c9] 3.059ms
> Unicast reply from 193.238.156.158 [0:15:6d:8a:ef:c9] 5.067ms
> Unicast reply from 193.238.156.158 [0:15:6d:8a:ef:c9] 2.032ms
> Unicast reply from 193.238.156.158 [0:15:6d:8a:ef:c9] 3.358ms
> Unicast reply from 193.238.156.158 [0:15:6d:8a:ef:c9] 1.960ms
> Sent 10 probes (10 broadcast(s))
> Received 6 replies
>
> -> nlq of 0.6
>
> as u get unicast replies (with retransmits), but send out broadcasts,
> u can measure #1 outgoing link-quality (NLQ) quite accuretely this way.
>
> to measure both directions, run it own both sides.
>
>
> Markus
>
> #1 without olsrd, or "any" requirements on the neighbours node.
>
> On Mon, Oct 24, 2011 at 2:45 PM, Denia Bouhired
> <(spam-protected) <mailto:(spam-protected)>> wrote:
>
> Thank you for your response. Would you be able to give me more
> detailed instructions on using arp for link sensing as we are not
> too sure on how to do that.
> Denia
>
>
>
> On 10/24/2011 02:39 PM, Markus Kittenberger wrote:
>> in a topology that small (3 nodes) fisheye makes no difference,..
>>
>> also rooting loops do not affect the link-sensing,..
>>
>> so there must be another (very likely not olsrd related) reason
>> to explain why the linkcsot between stationary nodes A and B
>> change when C moves away,..
>>
>> Markus
>>
>> p.s. maybe try to do your own linksensing,. to exclude your
>> wireless links really works.
>>
>> e.g. arping (with broadcasts) on both of your the links in both
>> directions
>>
>> On Mon, Oct 24, 2011 at 1:58 PM, Denia Bouhired
>> <(spam-protected) <mailto:(spam-protected)>> wrote:
>>
>>
>> Yes absolutely 100%.
>> The problem does not happen all the time. We thought it might
>> be related to infinite loops between two nodes updating one
>> another, hence why we though the fish-net algorithm.
>>
>>
>> On 10/24/2011 01:56 PM, Markus Kittenberger wrote:
>>> are u sure, your wireless interfaces are working (in adhoc
>>> mode)?
>>>
>>> Markus
>>>
>>> On Mon, Oct 24, 2011 at 12:41 PM, Denia Bouhired
>>> <(spam-protected) <mailto:(spam-protected)>> wrote:
>>>
>>> Hello all,
>>>
>>> Basically we're trying to run olsrd in embedded devices
>>> to create
>>> dynamic mesh networks. We have however been facing
>>> problems with olsrd
>>> that we are finding difficult to understand, let alone fix.
>>>
>>> In a simple 3 node setting with nodes A B C, we tried to
>>> cause some
>>> relaying to happen from A to C through B.
>>>
>>> A<--->B<--->C
>>> A<------------>C
>>>
>>> We have tried to do this both physically by moving nodes
>>> A and C out of
>>> sight of each other and also by introducing a link
>>> multiplyer in
>>> olsrd.conf between A and C. We tried both etx_ff and
>>> etx_fpm for this,
>>> with little improvement from both. Find attached the
>>> olsrd.conf file, we
>>> are using olsrd 0.6.3.
>>>
>>> In the case where we tried to break the link physically
>>> between A and C,
>>> by, say, having A and B fixed and C moving away from A
>>> but within LOS to
>>> C, such that:
>>>
>>> A<--->B<--->C
>>> A< x >C
>>>
>>> What happens is that the link between A and B starts to
>>> degrade even
>>> though the two of them haven't moved and only C has. If
>>> C comes back to
>>> it's original position than the link between A and B is
>>> re-established
>>> again.
>>>
>>>
>>> In another instance, of what we think is the same
>>> problem, we manage to
>>> establish a 2-hop link between A and C by forcing a link
>>> multiplyer
>>> between A and C so for instance
>>>
>>> t1: A<--------------ETX=4------------->C #Only two
>>> nodes in the
>>> network, only one route exists
>>> t2: A<---ETX=1--->B<---ETX=1--->C #Node B inserted,
>>> olsrd chooses lower
>>> cost route through B, ETX=2
>>>
>>> The switch between routes was seemless as soon as node B
>>> is up in the
>>> network. This result has been repeatable for any number
>>> of power off and
>>> reboots of node B, the routing table can switch between
>>> direct and 2-hop
>>> links without any problem. The problem has manifested
>>> itself when, for
>>> instance, node C is moved away, then, not only the links
>>> from A to B and
>>> B to C are lost (normal) but alarmingly the link between
>>> A and C also
>>> disappears from the topology and then it is impossible
>>> to re-establish
>>> communication between A and C unless olsrd is restarted.
>>> **Even though
>>> their state hasn't changed.**
>>>
>>> As you can see from the config file, we have enabled
>>> the fish-eye
>>> algorithm as we thought it might be a solution, but it
>>> hasn't made any
>>> difference as far as we can tell.
>>>
>>> This same problem has happend to us in various settings,
>>> but not
>>> consistently, so it has not been repeatable. I must also
>>> say that most
>>> times this had happened we had been trying to establish
>>> a VoIP link
>>> between A and C with B relaying the conversation.
>>>
>>> We are at loss as to what causes this problem and how to
>>> fix it, I hope
>>> my explanation has been detailed enough and that you'll
>>> be able to give
>>> me some suggestions.
>>>
>>> Cheers
>>> Denia
>>>
>>>
>>>
>>>
>>>
>>> --
>>> Olsr-users mailing list
>>> (spam-protected) <mailto:(spam-protected)>
>>> https://lists.olsr.org/mailman/listinfo/olsr-users
>>>
>>>
>>
>>
>> --
>> Dr Dénia Bouhired, Postdoctoral researcher
>>
>> EPFL - École Polytechnique Fédéral de Lausanne
>> Laboratoire de Communications Mobiles
>> INR-139, Station 14
>> CH-1015 Lausanne, Switzerland
>> Tel.: +41 (0) 21 693 81 11 <tel:%2B41%20%280%29%2021%20693%2081%2011>
>> e-mail: (spam-protected) <mailto:(spam-protected)>
>>
>>
>
>
> --
> Dr Dénia Bouhired, Postdoctoral researcher
>
> EPFL - École Polytechnique Fédéral de Lausanne
> Laboratoire de Communications Mobiles
> INR-139, Station 14
> CH-1015 Lausanne, Switzerland
> Tel.: +41 (0) 21 693 81 11 <tel:%2B41%20%280%29%2021%20693%2081%2011>
> e-mail: (spam-protected) <mailto:(spam-protected)>
>
>
--
Dr Dénia Bouhired, Postdoctoral researcher
EPFL - École Polytechnique Fédéral de Lausanne
Laboratoire de Communications Mobiles
INR-139, Station 14
CH-1015 Lausanne, Switzerland
Tel.: +41 (0) 21 693 81 11
e-mail: (spam-protected)
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