[Olsr-dev] process unspec. link quality information

Henning Rogge (spam-protected)
Tue Apr 14 10:56:27 CEST 2009

Am Friday 03 April 2009 11:54:48 schrieb Peter Tarjan:
> ---------------------------------------------------------------------------
>------------------------------ static void
> create_lq_hello(struct lq_hello_message *lq_hello, struct interface *outif)
> ...
>     // allocate a neighbour entry
>     struct lq_hello_neighbor *neigh = olsr_malloc_lq_hello_neighbor("Build
>     // a) this neighbor interface IS NOT visible via the output interface
>     if (!ipequal(&walker->local_iface_addr, &outif->ip_addr))
>       neigh->link_type = UNSPEC_LINK;
> ---------------------------------------------------------------------------
> I wondered when I looked into the code, why
> this information was even included in a HELLO packet.
You need this information to discover all 2-hop neighbors. Imagine an router 
with one interface connected to a router with multiple interfaces.

> In my network scenario B sends HELLO packets from both interfaces. Every
> HELLO packet lists all the links regardless which interface it is broadcast
> on.
Yes, that's correct.

> When these packets are processed, A is considering the first information
> that can be found in the packet about the LQ information of the link
> directed to it. So if there is an UNSPEC link first and later a SYM_NEIGH
> to A, UNSPEC link information is considered.
I had to look at the situation a little bit more closely and finally got that 
you are correct with your patch. The problem with this situation is that we 
have an OLSR instance with two interfaces receivable by the same interface of 
a second OLSR (for example two WLAN cards with the same channel).

I will pushed your patch and added a few more comments.


Diplom Informatiker Henning Rogge
Forschungsgesellschaft für
Angewandte Naturwissenschaften e. V. (FGAN) 
Neuenahrer Str. 20, 53343 Wachtberg, Germany
Tel.: 0049 (0)228 9435-961
Fax: 0049 (0)228 9435-685
E-Mail: (spam-protected)
Web: www.fgan.de
Sitz der Gesellschaft: Bonn
Registergericht: Amtsgericht Bonn VR 2530
Vorstand: Prof. Dr. rer. nat. Maurus Tacke (komm. Vors.), Prof. Dr.-Ing. 
Joachim Ender (Stellv.)

-------------- next part --------------
A non-text attachment was scrubbed...
Name: signature.asc
Type: application/pgp-signature
Size: 197 bytes
Desc: This is a digitally signed message part.
URL: <http://lists.olsr.org/pipermail/olsr-dev/attachments/20090414/53fe8c05/attachment.sig>

More information about the Olsr-dev mailing list