What does Router Advertisement do?

[Coolmax]

Hi,
I have HE tunnel working on my VPS. I'm setting up VPN for my own use and to enlarge knowledge about ipv6. I have pptp tunnel. On server side ppp0 has fe80::1 link-local address and client has fe80::2. If I start radvd with config below:

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interface ppp0
{
  IgnoreIfMissing on;
  AdvSendAdvert on;
  MaxRtrAdvInterval 60;
  AdvLinkMTU 1396;
  prefix 2001:470:xxxx:dead::/64
  {
     AdvOnLink on;
     AdvAutonomous on;
  };
};

I have to set route for client ip on server (eg ip -6 route add 2001:470:xxxx:dead::2 dev ppp0) and everything works fine. I tried to set routing and addresses on client (windows 7) side manually (identically), without RA. Tcpdump on server doesn't show any icmpv6 packet. I have to set address source to fe80::2 in order to capture any packets. Beside adding route and setting address, what else does RA do? I noticed also, that "netsh int ipv6 show neighbors" shows fe80::1 as router:

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netsh interface ipv6>show neigh vpn

Interfejs 38: VPN


Address                                       physical address   Type
--------------------------------------------  -----------------  -----------
2001:470:xxxx:dead::20                                           Stałe
fe80::1                                                          Stałe (Router)
ff02::2                                                          Stałe
ff02::c                                                          Stałe
ff02::16                                                         Stałe
ff02::1:2                                                        Stałe
ff02::1:3                                                        Stałe
ff02::1:ff00:2                                                   Stałe
ff02::1:ff00:20                                                  Stałe

Stałe means persistent. I see no option to set that manually. I want to understand this better, because I want to replace radvd with dibbler-server. If i start dibbler IP is assigned, DNS servers also, but I have no connection. Any help will be highly appreciated.

//Edit:
OK, I noticed that I can capture packets if host address part is same as in link-local address, but I don't know is this from IPv6 spec. or specified for MS OSes :)

Kind regards,
Matthew Pałosz