Thank you Rob, for your information,
Below is my dropped packets since yesterday
6987 997K DROP udp -- tunl0 * 0.0.0.0/0 0.0.0.0/0 udp spt:5678
I did not realise that regardless of my actions tcpdump would still show the " offending " packets. If I remain with my current settings I will not be broadcasting the router discovery packets should I start to receive more.
Regards, Ian..