[Olsr-dev] process unspec. link quality information

[Henning Rogge]

On Dienstag 31 März 2009 16:43:44 Peter Tarjan wrote:
> Hello,
>
> I've downloaded, compiled and tested the recently released OLSRd version 0
> .5.6-r4.
> In most situations it worked perfeclty, but olsrd behaved not as I expected
> in the following scenario:
> - two computers (A and B) having 1 and 2 network cards (respectively)
> involved in routing algorithm;
> - the packets from A to B arriving on B's 1st interface are dropped
> (asymmetric link emulation), while packets received on B's 2nd interface
> are accepted and processed.
>
> A -> B/1 dropped
> A -> B/2, B/1 -> A, B/2 -> A - OK.
>
> In this situation A measures two perfect links (ETX=1), even from B/1, so
> the A -> B/1 neighbor link quality is considered flawless.
> I think I found its cause: we got link quality information from our
> neighbours, but we memorize it even if it is marked as UNSPECIFIED.
>
> The unexpected behaviour can be fixed by the following patch:
>
> --- a/src/process_package.c    2009-03-31 16:12:14.215112467 +0200
> +++ b/src/process_package.c    2009-03-31 16:13:05.643112066 +0200
> @@ -424,7 +424,9 @@
>
> @@ -424,7 +424,9 @@
>
>      /* find the input interface in the list of neighbor interfaces */
>      for (walker = message->neighbors; walker != NULL; walker =
> walker->next)
> -      if (ipequal(&walker->address, &in_if->ip_addr))
> +      if (ipequal(&walker->address, &in_if->ip_addr)  &&
> +            walker->link != UNSPEC_LINK)
> +
>          break;
>
>      // memorize our neighbour's idea of the link quality, so that we

Hmm... I'm not sure about this patch... shouldn't we set the LQ value to zero 
for an unspecified link at another place ?

With your patch we might just ignore the value measured by the UNSPEC-link 
(correct) and keep the old LQ value !

Henning
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