current 6to4 state

Ivan Shmakov oneingray at
Mon Nov 12 06:49:12 CET 2012

>>>>> Steinar H Gunderson <sesse at> writes:
>>>>> 2012/11/10 Ivan Shmakov <oneingray at>:

 >> Which makes me wonder on what are the costs of operating one's own
 >> “IPv6-to-6to4” relay?  As it seems, the “no valid route to
 >>” case is much easier to troubleshoot that the converse
 >> “no valid route to 2002::/16” one, so the latter may indeed deserve
 >> some extra care.

 > It's simple; if you wish, you can add a 6to4 decapsulation on every
 > server if you wish.

	Well, my question was about 6to4 /encapsulation/, actually.

	AIUI, there's likely to be just a single 6to4 relay
	decapsulating the packets sent from 6to4 hosts to the IPv6 nodes
	proper.  However, there'll be a lot of such relays on the
	reverse direction, and thus it's the broken /encapsulating/
	relay case that'd likely be much harder to troubleshoot.

 > I've done it a few times, with a marked increase in reliability to
 > 6to4-using hosts.  (Nowadays it's quite irrelevant, though, since
 > 6to4 is all but extinct.)

	My numbers are hardly representative (and are rather a
	back-of-the-envelope calculation), but while operating a
	BitTorrent DHT6 node for a short time, I've observed that 6to4
	constitutes over 90% of all /48 prefixes seen, being responsive
	for 36% of all messages seen by the node.  The latter number, if
	any, should be more representative of the present 6to4
	deployment, due to the possibility of 6to4 nodes using a dynamic
	IPv4 address, and thus more than one IPv6 /48 prefix, and also
	because /48 may prove itself a bit coarse for the native IPv6

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