[Olsr-dev] [olsr-dev] Quagga plugin fixes

Sven-Ola Tuecke (spam-protected)
Tue Jul 3 11:56:46 CEST 2007

Just some more blurb.

Someone may notice the "Pre-Add Route" messages in that output. This is an 
experimental approach to cope with frequent routing changes triggerd by 
different hops / metrics. There is no "Change Route" command (neither ioctl, 
nor rtnetlink). So you have to remove an old route and add the changed one. 
Which may introduce a (short) time with no route to an arbitrary endpoint  - 
resulting in ICMP host unreachable and/or unsuccessive ARP lookups.

At least with Linux, it is legal to have the same route concurrently if the 
metric is different. "Pre-Add Route" means: First insert new route, then 
remove old route. If error: revert to old  behaviour. Yes I know - there's a 
routing cache (once again: at least within the Linux kernel) with some 
flushing algo (2 seconds? triggered when?). Did I wrote it's experimental to 
some extent?

// Sven-Ola 

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