[Olsr-dev] Some reflections on link state routing and metrics

Markus Kittenberger (spam-protected)
Tue Feb 10 13:04:41 CET 2009

> Yes, I agree this is a good idea. But to trigger the issue I'm discussing
> you don't need fluctuating links. Just two alternativ high cost links

> that are both changing at low relativ rate in the same direction.

hmm changes at a low rate, should not be announced, until they get relevant
i think,..
so we need less TCs

and are u really sure that a change in a high cost link, will make troubles?
if there is no fisheye, and no packetloss on the low-cost links, and no


A-B cost 1000
A-C cost 998
B-C cost 1

i think you are frightened, that if A-C changes to 1002 (a very small change
compared to costs of 100 but a huge one compared to cost of 1)

and due to packetloss only C gets informed about,..

if now C want to send somethin to A it will send to B csot of 1001 (1+1000)
but B will send it back to C as B thinks this means costs of 999 (1+998)

but: if there`s no fishey and no packetloss, C would have told B of the
cost-change between A-C, and everything is fine

of course above assumptions about no fisheye (causing packetloss at arbitray
positions) and no packetloss on low-cost links MUST hold true, to have only
very short lived loops,

> Sorry, I have been (too) short: What I wanted to write was: "funkfeuer
> to have long *default* routes compared to freifunk". I don't have any
> actual data about freifunk networks but I would be very surprised if this

> was wrong. And loops in the default route is, what people usually notice

Yes but actually (see my previous mail) we have the peak at 3 hops from main
gateway (viviroof) to a node

and the return path is about 0,5 hops shorter in average, as more than halve
of 0xff nodes reach a secondary (outgoing only) gateway (kryptaroof,
tunnelserver) one hop earlier than they would reach viviroof,
so we have mostly very short routes here in vienna
but i think with multiple uplinks a freifunk-mesh should behave even
shorter, regarding default routes
of course routes from one node to all others nodes in a freifunk-mesh would
tend to be longer as in veinna, as there is no usually no centralistic
(backbone) aproach in them,..
so i want some useful data to compare, but it not so important, there should
and then whether the route has usually about 3 hops or 5 hops is quite
unimportant,.. *g
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