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Re: IPv6 router is not forwarding packets




Hi Ulf,

many thank again for your reply. 

Am Sonntag, 6. Januar 2019, 21:40:21 CET schrieb Ulf Volmer:
> Yes, looks weird. I have no idea why this happens.
>
> Just one point, the response times of hop 3 in your second traceroute
> are quite low (instead of hop 2 in the first one). Are you sure that hop
> 3 isn't somewhere in your LAN?

Good observation. I mirrored the traffic to the ISP router (fritz.box) to 
another unused switch port and used tcpdump to record it.

Looks unsuspicious to me. I see the traceroute packets outgoing (three per hop 
limit as from home). The only difference is that the I get an "administratively 
prohibited" type back (probably what traceroute marks with the X).

https://scw.bokomoko.de/~rd/icmpv6.png
shows a screenshot of the first ICPMv6 packet which returns from the "wrong" 
IPv6 address. 

>From your observation on the timings, I would conclude that the packet does 
not leave the IP router (fritz.box). The only surprising thing is that the 
source ipv6 address is not the router address but some other address 
2a02:8070:8900:0:30a0:caa7:42e0:93d2 .

To me it seems almost like an issue of the ISP router (fritz.box). The 
fritzbox documentation contains a section

"Configure the IPv6 router so that it requests its own prefix from the FRITZ!Box 
using IPv6 prefix delegation and that it announces its routing information to 
the FRITZ!Box via router advertisement."

https://en.avm.de/service/fritzbox/fritzbox-7390/knowledge-base/publication/
show/1239_Setting-up-an-IPv6-subnet-in-the-FRITZ-Box/

Which routing information does the fritzbox need? Do I need radvd for that?

Thanks
Rainer



-- 
Rainer Dorsch
http://bokomoko.de/