[OLSR-users] experiences with LinkQualityMult limits

Thomas Lopatic (spam-protected)
Mon Feb 28 13:08:35 CET 2005

Hi Andreas,

Yes, there exist two thresholds for the link quality.

1. As Stefan has already pointed out, we represent link quality values 
as a single-byte fixed-point number in OLSR messages. 255 represents 
1.0, ..., 1 represents 1 / 255 = 0.0039, and 0 represents 0.0. When 
converting floating point numbers into the single-byte value, we always 
round down. So, everything below 1 / 255 is treated as 0.

2. In lq_route.h you find a macro named MIN_LINK_QUALITY. This is set to 
0.01 by default. Links that have a link quality below MIN_LINK_QUALITY 
in either direction are ignored. So, the maximal ETX is 1 / 
(MIN_LINK_QUALITY x MIN_LINK_QUALITY) = 10,000. The idea behind such an 
artificial limit is to keep the path ETX values below 2 ^ 30, which is 
what I use to represent infinity for the Dijkstra algorithm (see 
INFINITE_ETX in lq_route.h).


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