Linux IPv6 routing strange behaviour

[Hannes Frederic Sowa]

On Wed, Aug 14, 2013 at 01:49:23PM +0300, Max Tulyev wrote:
> /proc/sys/net/ipv6/route/max_size - 100000. Route table grows to 100000
> entries, and then drops to almost zero. Then cycle again.
> 
> But it should not be more than 14000, if mean both local and global
> routes...

Try increasing it more. Perhaps the errors there bring quagga into a
state where it flushes the routes and tries to inject them again.

If a packet is delivered to a destination, we clone the routing entry and
reinsert it back into the fib trie. This is needed because we need to track
pmtu and other stuff in this routing node. In contrast, IPv4 is using nexthop
exceptions here which store this information in hash tables placed right to
the statically configured fib_node. I would like to have this scheme one day
for IPv6, too, because it enabled to do the linux kernel a lot more sharing
between the nh-exceptions.

But in contradiction to common believe, there is no routing cache as there was
once for IPv4. ;)

Greetings,

  Hannes