Re: [Snac] Router using Ipv6 prefix length = 67

[Jonathan Hui <[e-mail]>]

Hi Alan,

Thanks for sharing this information.

It seems the Netgear WNP3000 is not conformant to RFC 7084 Section 4.3
<https://datatracker.ietf.org/doc/html/rfc7084#section-4.3> and RFC 2464
Section 4 <https://datatracker.ietf.org/doc/html/rfc2464#section-4>. That
said, I think it makes sense for the stub router implementation to be
defensive in these situations and include prefix length in the definition
of a "usable prefix".

As for spec text, draft-ietf-snac-simple-01 Section 5.1.1 already states:

   IPv6 addressing is considered to be present on the link if a usable
   on-link prefix is advertised on the adjacent infrastructure link.  A
   usable on-link prefix is a prefix advertised on the link that has a
   preferred time of 30 minutes or more, is marked on-link and allows
   autonomous configuration.

One could argue that "allows autonomous configuration" already covers this
requirement, given that RFC 2464 Section 4 states:

   An IPv6 address prefix used for stateless autoconfiguration [ACONF]
   of an Ethernet interface must have a length of 64 bits.

If we wanted to make a change, we could add some clarifying text like:

   A prefix that allows autonomous configuration includes having the PIO
   A-flag set to 1 and required prefix length for the given link.

Thoughts?

--
Jonathan Hui



On Sun, Jun 4, 2023 at 10:33 AM Collins, Alan <alaclli=
[e-mail]> wrote:

>
>
> Hello Ted, Jonathan.
>
>
>
>                 We have multiple test setups testing Matter over Thread
> back-to-back pairing while connected to infrastructure using different
> (hundreds) of Wifi AP with default settings. The setup:
>
>
>
> Recently, while using Netgear WNP3000 , the Matter pairing failed. The
> non-thread matter controller is not getting an IPv6 global address, so even
> that the routing table contains the prefix to reach into the Thread BR, the
> IP stack does not allow it without a global IP of its own.
>
>
>
> Thread BR is only sending icmpv6 RA with RIO. The PIO is not included
> because there is another router in the network already sending PIO.
>
> However, since that PIO has length = 67, the non-Thread matter controller
> won’t use it to create a global IP. It’s not even sending NS for DAD.
>
>
>
>
>
> We think the abnormal ipv6 PIO prefix RA is from the backend Cisco OUI MAC
> address. We are investigating.
>
>
>
> However, this opens an opportunity to create a more robust behavior from
> Thread BR, to add more logic into processing the existing PIO before
> deciding not to send a PIO of its own.
>
>
>
> Thank you in advance for looking into this.
>
>
>
> Cheers,
>
> Alan Collins
>
>
>
>
>
>
> --
> Snac mailing list
> [e-mail]
> https://www.ietf.org/mailman/listinfo/snac
>