IPv6 BGP & kernel 4.19

[Vincent Bernat]

 ❦  3 décembre 2019 11:46 +01, Alarig Le Lay <alarig at swordarmor.fr>:

> So, I have more routes in cache than in FIB on my two core routers, I’m
> pretty sure there is a bug there :p

It's not unexpected. A cache entry is for a /128.

> I have less routes in cache on 4.14 kernels but more traffic.
>
> I don’t know which function is feeding the cache, but I think that it’s
> doing too much.

The function is ip6_rt_cache_alloc(). It is being called on PMTU
exceptions, on redirects and in this last case I currently fail to
understand:

> ipv6: Create RTF_CACHE clone when FLOWI_FLAG_KNOWN_NH is set
> 
> This patch always creates RTF_CACHE clone with DST_NOCACHE
> when FLOWI_FLAG_KNOWN_NH is set so that the rt6i_dst is set to
> the fl6->daddr.


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