Point-to-Point interfaces and routing

[Alexander Motin]

Hello.

I have found to myself strange behaviour and difference between routing 
to IPs on ngX, tunX interfaces. I will be very grateful if somebody 
explain me why it is working in such way or give me a link to some good 
manual about this.

I have 6.1-STABLE. Do preparations:
Create two interfaces, ng0 (by ngctl) and tun0 (by running interactive ppp).
Bring them down and then up with ifconfig.
Now they looks like:
ng0: flags=88d1<UP,POINTOPOINT,RUNNING,NOARP,SIMPLEX,MULTICAST> mtu 1500
         inet6 fe80::211:2fff:fea9:7627%ng0 prefixlen 64 scopeid 0x4
tun0: flags=8051<UP,POINTOPOINT,RUNNING,MULTICAST> mtu 1500
         inet6 fe80::211:2fff:fea9:7627%tun0 prefixlen 64 scopeid 0x3
         Opened by PID 11956

Questions:
1. If I look for the routing tables I see:
fe80::211:2fff:fea9:7627%ng0  fe80::211:2fff:fea9:7627%ng0  UHL ng0
fe80::211:2fff:fea9:7627%tun0 link#3                        UHL lo0

So now I can ping ip on tun0, but can't on ng0. Why did they different 
and what is right?

When I am trying "route get -inet6 other_onlink_ip" I see:
%route get -inet6 fe80::211:2fff:fea9:aaaa%tun0
   interface: tun0
       flags: <UP,DONE,CLONING>
%route get -inet6 fe80::211:2fff:fea9:aaaa%ng0
   interface: ng0
       flags: <UP,DONE>

They are something different even here.

2. Add IPv4 addresses to both link:
ng0: flags=88d1<UP,POINTOPOINT,RUNNING,NOARP,SIMPLEX,MULTICAST> mtu 1500
         inet 10.0.0.1 --> 10.0.0.2 netmask 0xffffffff
tun0: flags=8051<UP,POINTOPOINT,RUNNING,MULTICAST> mtu 1500
         inet 10.0.1.1 --> 10.0.1.2 netmask 0xffffffff

Now I can ping neither 10.0.0.1 nor 10.0.1.1 because routing goes to my 
default. Why if it is my local ips?

If I add routes to 10.0.0.1 and 10.0.1.1 via lo0, I can ping them. Why 
now it works and is this right?

3. mpd ppp daemon on interface up event adds route for the local ip to 
the lo0. Is it right way? And how in theory it must work for IPv6?

-- 
Alexander Motin