[atlas] [ipv6-wg] What to do with RIPE Atlas probes that have only a ULA as IPv6 address?

If those probes with ULA, aren¹t able to connect to v6 Internet, for
example using NPT, then should be considered as non-IPv6 enabled. IPv6 is
not broken, is just meant for LAN connectivity. If ³broken² for you mean
no-Internet connectivity, then is broken ;-)

And yes, the CPE is doing the right thing, it has been configured to use
an ULA to allow LAN IPv6 connectivity.

Regards,
Jordi






-----Mensaje original-----
De: Philip Homburg <philip.homburg at ripe.net>
Responder a: <philip.homburg at ripe.net>
Fecha: miércoles, 25 de marzo de 2015, 11:31
Para: "ripe-atlas at ripe.net" <ripe-atlas at ripe.net>, <ipv6-wg at ripe.net>
Asunto: [ipv6-wg] What to do with RIPE Atlas probes that have only a ULA
as IPv6 address?

>Dear community members,
>
>The RIPE Atlas team has a question what to do with probes that have only
>a Unique Local IPv6 Unicast Address (ULA) [RFC4193] as their IPv6
>address. The question is whether to treat those probes as IPv6 capable
>or not.
>
>It is known that about 10% of the RIPE Atlas probes that have IPv6
>addresses do not actually have IPv6 connectivity. This was documented by
>Stéphane Bortzmeyer in his RIPE Labs article "How Many RIPE Atlas Probes
>Believe They Have IPv6 (But Are Wrong)?"
>(https://labs.ripe.net/Members/stephane_bortzmeyer/how-many-atlas-probes-b
>elieve-they-have-ipv6-but-are-wrong)
>
>As a way of dealing with this problem, the RIPE Atlas system now tags
>probes that have broken IPv6. Any probe that has an IPv6 address (other
>than link local) but cannot reach the global internet is tagged as "IPv6
>Doesn't Work" (see https://atlas.ripe.net/docs/probe-tags/)
>
>At the moment, around 2800 probes are connected and have an IPv6
>address. Of those probes, around 350 (12.5%) are tagged that IPv6
>doesn't work. Of those 350 probes, 114 have the surprising condition
>that the connect system call fails immediately with the error 'Network
>is unreachable.'
>
>Those 114 probes have two things in common, they have only a ULA address
>and the do not have a default route. It is the lack of default route
>that causes the connect system call to fail immediately.
>
>This feature (ULA and no default route) is specified in RFC-7084 (IPv6
>CE Router Requirements) requirement ULA-5 ("An IPv6 CE router MUST NOT
>advertise itself as a default router with a Router Lifetime greater than
>zero whenever all of its configured and delegated prefixes are ULA
>prefixes.") The surprising thing is that for some probes this condition
>persists for many months.
>
>For the Atlas project, the question is how we should treat these probes.
>Currently they are regarded as having broken IPv6 connectivity. However,
>an alternative is to consider those probes as having no IPv6 at all.
>
>Broader questions are: are CPEs doing the right thing here. Should a CPE
>announce a ULA on the local LAN even if there hasn't been any IPv6
>internet connectivity for a very long time? It is already complex enough
>for normal users to understand that there is always a link local IPv6
>address even if there is no IPv6 connectivity. Now we have to add ULA to
>that group as well.
>
>So the question to the community, should RIPE Atlas treat ULAs in the
>same way as RFC-1918, addresses that should be ignored unless a valid
>global address can be found elsewhere. Or should we keep the current
>approach where ULAs are treated just like other global IPv6 addresses
>and consider the probe host's network setup to be broken?
>
>Philip
>
>




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