Here is our scenario.
Currently, when pinging any interface on Router2 with 50 packets 100bytes each from Router1, the result is 100%. Change it so the success rate is always 96%.
Assuming FastEthernet Interfaces.
Router1 - Router2
—Configure control plane policing on Router2
access-list 110 permit icmp host [Router1] host [Router2] echo
class-map ICMP
match access-group 110
policy-map ICMP
class ICMP
police rate 80 pps
control-plane
service-policy [...]

I ran into a weird problem the other day where my IPv6 OSPF adjacency kept flapping every 40 sec(dead timer) and then reestablishing.
Before you go crazy trying to troubleshoot this problem, check this:
1. Check to see if there is a switch in between your IPv6 routers, make sure this switch supports IPv6! if there is [...]