[Olsr-users] Calculating LQ in 0.5.0 (Was: olsrd-0.5.0: LQ

[Alexey Shinkin]

Maybe would be better to post this to developers as well ... but I thought 
this could be interesting for users.  
 
Sven-Ola's  “slow-start LinkQualityWinSize” has a nasty side effect , I’m a bit surprised it hasn’t been noticed yet .
(even by practical guys … ).
 
While LQ=(total-lost)/window_size all seems ok .
 
As we gather enough packets , LQ = (total-lost)/super_optimized_stuff   and it starts to be greater than 1.0
 (in good link condition).
 
Now guess what happens if you scale such LQ  (yeah, multiply this by 255 and cast to unsigned char!)
and send it to neighbors via LQ HELLO message ;) 
 
Right, they’ll got NLQ  slightly more than 0 ! 
 
Even funnier, they’ll return that NLQ to you with TC , you’ll see your own LQ>1.0 in Links section and ~0 in Topology !
 
Simply clipping LQ to 1.0  solves the problem . 
 
Thanks
 
Alexey Shinkin
 
 
_________________________________________________________________
Express yourself instantly with MSN Messenger! Download today it's FREE!
http://messenger.msn.click-url.com/go/onm00200471ave/direct/01/
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.olsr.org/pipermail/olsr-users/attachments/20070824/848c6fd7/attachment.html>