Yenya's World

Wed, 10 Feb 2010

Playing with 6to4

We have finally got some time to work on native IPv6 inside a faculty network (which includes rewriting the iptables configuration to be protocol-neutral). In order to test it, I have enabled 6to4 at home.

So now I have a native IPv6 in my home network, and I can even directly SSH to devices in my home network from the university network, even though the home network is hidden behind a single IPv4 address. Apparently my traffic is routed symmetrically, as both directions use the same 6to4 relay in in Nuernberg.

As for the network parameters, I have a direct ping 13.2 ms, while the ping6 is 27.1ms. The transfer rate, on the other hand, is purely limited by my ISP (measured by SCPing a large file), and it is the same for both protocols - slightly above 500 KB/s. Now if only I had a nearer 6to4 relay (maybe in NIX.CZ?).

The setup in Fedora is relatively straightforward, except when the outgoing interface has an IPv4 address assigned from DHCP. So I had to add the IPv6 configuration manually, and will have to change it whenever I get a new IPv4 address (which is usually once per year or two).

UPDATE 2010/02/10: Fedora problems fixed
My previous statement about problems in Fedora was not true. I must have made a mistake somewhere, but after recheking my setup and restarting the network the 6to4 tunnel works as expected.

Section: /computers (RSS feed) | Permanent link | 4 writebacks

4 replies for this story:

petr_p wrote:

I have used 6to4 for many years without any serious problem. I had to switch relay address to get better RTT few times (IP Exchange GmbH; Universität Leipzig; Limited, UK). List of AS announcing anycast relay can be found on . However I'd really appreciate public relay in Czech Republic. (Why Cesnet does not have one, at least for members? NACEVI streams wouldn't flow abroad then.) BTW, are you going to resurrect Which services is faculty going to offer on IPv6? (I remember almost a hundred of machines responded to ff02::1 echo request in faculty computer hall, but no global scope addresses was available.) Which DHCPv6 server are you going to install? Dibbler?

petr_p wrote: List of ASes

List can be found on []. (Yet another CMS discarding angle brackets.)

Yenya wrote: Re: petr_p

I should poke the CESNET people to create the 6to4 relay. Yes, I want to resurrect the service (or even add an AAAA record to the name). For now, we want to create 3rd-layer infrastructure for IPv6, and then the services will follow. We have still not decided what DHCPv6 (or whether DHCPv6 at all instead of stateless config (aka radvd)).

petr_p wrote:

I prefer router advertisement too. However DHCP allows to deliver other important settings like default search domain name suffix, local time zone, outbound SIP proxy address etc. You can use DHCP in stateless mode too. Recursive DNS servers can be delivered through DHCP or radvd (but Linux support for RDNS option extraction from RA is poor).

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