startd radvd on router in debug mode (just stop radvd and then run it using radvd -d 5). be also sure to have ipv6 forwarding enabled nn this router (echo 1 > /proc/sys/net/ipv6/conf/all/forwarding).
on the computer in local network you can start radvdump, very usefull tool to monitor RA. You can eventually use "tcpdump -i eth0 -n" for the same purpose. Be also sure to make ipv6 forwarding DISABLED on this machine, as if it will have it enabled kernel will ignore RA packets, and will NOT autoconfigure addresses and routes.
below is simple config
PS. It is also better to use iproute2 tools to configure networking in linux. just call "ip a" to display everything about addresses, and "ip r" about routes. more info in manpages and help.