[Olsr-users] OLSR mesh with loop potential... having problems.

Markus Kittenberger (spam-protected)
Sat Oct 6 21:23:27 CEST 2012


On Fri, Oct 5, 2012 at 7:14 AM, Vigneswaran R <(spam-protected)> wrote:

>  Dear all,
>
> Recently we also noticed loops in the routes established by OLSRv1, on a
> partial mesh topology (with ~20 machines). We are using olsr 0.6.3 with
> default configuration file and only Interface line has updated. Not using
> any plugins. As of now wired connections and at the deployment will be
> using wireless radios.
>
> Due to the loop, the packets sent through one Interface and received on
> another.
>
you mean return packets just took another route as the packets towards?

this is normal, and you need e.g just 4 nodes with all having 2 etx-1.0
links, aligned in a square, to have a 50% chance to get this, and imho
there is nothing wrong about this,..

Markus


> ssh, ping worked fine regardless of that. However, we realized the loop
> when 'nmap' erroneously reported a node as down.
>
> One point to note here is, when we conducted the test we used 10.0.0.0/8subnet for all the nodes, so that we can do random reconnects to simulate
> node movements. However, Henning suggested to put different Interfaces of
> the same router into different subnets (in his reply on another thread).
> So, when we do the tests again we will see whether that has any impact on
> loops.
>
> However, whether loop in routes are expected in general, for such
> topologies? or by doing some configuration changes can we avoid that?
>
> Thank you.
>
>
> Regards,
> Vignesh
>
>
>
>
> On Wednesday 27 June 2012 03:24 AM, √Črico Porto wrote:
>
> I think he meant a file containing the following lines
>
>  IpVersion 4
> Interface "wlan0"
> {
> }
>
> √Črico V. Porto
>
>
> On Tue, Jun 26, 2012 at 4:27 PM, John Clark <(spam-protected)> wrote:
>
>>
>>  On Jun 26, 2012, at 12:06 PM, Markus Kittenberger wrote:
>>
>>
>> On Tue, Jun 26, 2012 at 8:29 PM, John Clark <(spam-protected)> wrote:
>>
>>> Thanks all,
>>>
>>> I updated my olsrd to the 6.3 version that's on the download page.
>>> Compiled ok, and did an install and 'install_libs', which seems to have
>>> cured my problem with loading the plugins.
>>>
>> (you could have done an install_all)
>>
>>
>>> I used the default installed olsrd.conf, and only changed the interfaces
>>> list.
>>>
>> try to use a new olsrd.conf (i.e an absolutely empty one except the
>> protcol version ipv4 or ipv6 and the interface names)
>>
>>
>>  I believe I'm using that conf, all I changed was the interface list.
>>
>>  I'll recheck that...
>>
>>
>>  this will use default settings for everything, and might cure your
>> actual problems,..
>>
>>  As a note, in the past, upon reflection, my 'meshes' have been either
>>> linear chains or trees, and there have bee no internal loops.
>>
>>
>>  olsrd works on such topologies, as infact such topologies are what it is
>> meant to operate on.
>> (it definetely does not need the networks to be a tree,..)
>>
>>
>>  I've been working on this more, and will try to give more details as
>> they come to me, but at the moment, I have the problem when the one link is
>> removed, problems arise.
>>
>>
>>  Thanks,
>> John Clark.
>>
>>
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>>
>
>
>
>
>
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