IPv6 Router Advertisement with 6to4

GZ15 · Fri Sep 30, 2011 6:31 am

Hello,

I am a happy user of RouterBoard 450G with RouterOS 5.7. So far I've been rather successful with configuring everything, even IPv6 functionality. I was however unable to set up IPv6 Router Advertisement for the local network. I've found several howto's or guides with slightly different instructions, and I've also found one thread here on the forums and none of them helped me.

So, I have a working 6to4 tunnel (I can ping ipv6 addresses and domains from routerboard itself) but I can not manage to distribute my subnet and routes to local computers.

I have a default configuration - ether1-gateway is used for Internet access, ether2 ~ ether5 are bridged for LAN.

Here's my 6to4 configuration:

[admin@MikroTik] > /ip address print 
Flags: X - disabled, I - invalid, D - dynamic 
 #   ADDRESS            NETWORK         INTERFACE                               
 0   ;;; default configuration
     10.0.0.1/24        10.0.0.0        ether2-local                            
 1 D 80.243.x.y/26   	80.243.x.y      ether1-gateway 
 
 [admin@MikroTik] /ipv6 address> print
Flags: X - disabled, I - invalid, D - dynamic, G - global, L - link-local 
 #    ADDRESS                                     INTERFACE            ADVERTISE
 0  G 2002:<6to4_IP>::1/3                         sit1                 no       
 1  G 2002:<6to4_IP>:1::1/64                      ether1-gateway       no       
 2  G 2002:<6to4_IP>:2::1/64                      ether2-local         yes      
 3 DL fe80::<6to4_IP>/128                         sit1                 no       
 4 DL fe80::20c:42ff:feaf:420e/64                 ether1-gateway       no       
 5 DL fe80::20c:42ff:feaf:4212/64                 bridge               no       
 
 [admin@MikroTik] /ipv6 address> /ipv6 route print 
Flags: X - disabled, A - active, D - dynamic, 
C - connect, S - static, r - rip, o - ospf, b - bgp, U - unreachable 
 #      DST-ADDRESS              GATEWAY                  DISTANCE
 0 ADC  2000::/3                 sit1                            0
 1   S  2000::/3                 ::192.88.99.1%sit1              1
 2 ADC  2002:<6to4_IP>:1::/64    ether1-gateway                  0
 3 ADC  2002:<6to4_IP>:2::/64    bridge                          0

So, essentially, sit1 is the 6to4 tunnel and has subnet :0::/64, ether1-gateway has :1::/64 and local network has :2::/64. Two side-questions arise:
1) Is it necessary for ether1-gateway to have an IPv6 address? Or would it be possible to operate just with sit1, i.e. reaching my RouterBoard from the Internet. I am not entirely sure how exactly ether1 plays its role in 6to4 tunnel.
2) Is there a difference between assigning an address to ether2 and 'bridge'?

But to my original problem - settings shown above are those which I created. Setting posted below are the ones which were already in the router, I didn't change/add anything (or rather I did and it didn't help):

 [admin@MikroTik] /ipv6 nd> /ipv6 nd print
Flags: X - disabled, I - invalid 
 0   interface=all ra-interval=3m20s-10m ra-delay=3s mtu=unspecified 
     reachable-time=unspecified retransmit-interval=unspecified 
     ra-lifetime=30m hop-limit=unspecified advertise-mac-address=yes 
     advertise-dns=no managed-address-configuration=no other-configuration=no
	 
	 [admin@MikroTik] /ipv6 nd> /ipv6 nd prefix print 
Flags: X - disabled, I - invalid, D - dynamic 
 0  D prefix=2002:<6to4_IP>:2::/64 interface=bridge on-link=yes autonomous=yes 
      valid-lifetime=4w2d preferred-lifetime=1w

I have a Windows Vista computer in my network with IPv6 enabled. It has a link-local address, however it does not obtain any other address (from RA or anywhere else). Is it possible I forgot to enable something somewhere?

I am sorry if this question is incomplete - please let me know if there is any other information needed.

Thank you,
GroundZero

fewi · Fri Sep 30, 2011 7:05 am

At a quick glance that looks OK.

There used to be a problem with RAs on switched ports (groups of ports with a master port set). I no longer have any switched ports on my home RB750G, they're all routed ports for that reason, so I don't know if this ever got fixed. It may have, in which case I apologize in advance for leading you down the wrong path.

Try these two things: turn on logging for RAs and check for errors in the logs. Add a topic for radvd with an action of memory and wait for the advertisement interval, it should tell you if it skipped sending for some reason.
Also run Wireshark on the Vista machine and filter for icmp6 and see if you actually see any advertisements. I'm betting no, but it'll help you rule out the client.

GZ15 · Fri Sep 30, 2011 12:19 pm

I feel like an idiot again. I've started WireShark, set filter to ICMPv6 and saw a lot of pings coming from some 2001: IP address. I wondered how is that possible so I looked and there it was - my computer had the IP addresses from my 6to4 tunnel already.

Sooo yet again, something didn't work automagically before or it just took some time to advertise the addresses and routes but now it works just as expected. It's the case when you try everything, every angle, every wiki, then you finally resort to starting a big forum thread and just after you do that everything starts to work or you figure it out at that moment.

That being said I am very thankful for your quick response and I am sorry for starting this (now useless) thread. I guess you could delete it.

Thanks again and sorry for your time!

IPv6 Router Advertisement with 6to4

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