Bug#678519: general: after about 1 month of uptime, routing of IPv6 packets is no longer possible, and IPv4 routing becomes slow and unpredictable. Rebooting brings all functionality back, and back to speed. so far the best way for me to discover is to try a ping6, and reboot the firewall (this machine), when ping6 from the inner network fails.

[Henrique de Moraes Holschuh <hmh@debian.org>]

On Fri, 22 Jun 2012, Rudy Zijlstra wrote:
> let system run with IPv4 & IPv6 routing for about 1 month
> > IPv6 routing will start to fail
> > IPv4 routing becomes slow and unpredictable
> 
> no obvious causes visible in the system. top and friends do not show a cpu hog
> 
> a reboot will bring the system back to normal behaviour. 

Please use (as root) "ip neigh show", and "ip route list cache" to try to
track down any weird differences between the box when it is behaving
normally, and the box when wedged.  You may want to compare it to a healthy
box on the same network segment.

You can also try to see if "ip route flush cache" and "ip neigh flush" can
unwedge the system.  After a flush, "ip neigh show" and "ip route list
cache" should return very few, if any, entries.

-- 
  "One disk to rule them all, One disk to find them. One disk to bring
  them all and in the darkness grind them. In the Land of Redmond
  where the shadows lie." -- The Silicon Valley Tarot
  Henrique Holschuh