[ipv6hackers] IPv6 in GCP (WTH?): default route

[Andrew Walding]

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On Mon, Jan 2, 2023 at 8:40 AM Fernando Gont <fernando at gont.com.ar> wrote:

> Hi. all,
>
> I happen to be playing with IPv6 on GCP, and seem to find a few
> "interesting" things.
>
> RAs on the IPv6 subnet are as follows:
>
> ---- cut here ----
> rdisc6 ens5
> Soliciting ff02::2 (ff02::2) on ens5...
>
> Hop limit                 :    undefined (      0x00)
> Stateful address conf.    :          Yes
> Stateful other conf.      :           No
> Mobile home agent         :           No
> Router preference         :       medium
> Neighbor discovery proxy  :           No
> Router lifetime           :            0 (0x00000000) seconds
> Reachable time            :  unspecified (0x00000000)
> Retransmit time           :  unspecified (0x00000000)
>   Source link-layer address: 42:01:0A:0B:00:01
>   MTU                      :         1460 bytes (valid)
>   Route                    : 2600:1900:4121:3b52::/65
>    Route preference        :       medium
>    Route lifetime          :           90 (0x0000005a) seconds
>   from fe80::4001:aff:fe0b:1
> ---- cut here ----
>
> As you can tell from the RA, it has a Router Lifetime of 0, so a
> compliant implementation will not install an IPv6 default router.
>
> (yes, the router sending this RA will work okay as a default router if
> you manually configure it as such, though).
>
> GCP claims that you can get the default route for an interface by
> querying the local metaserver
> (
> https://cloud.google.com/compute/docs/ip-addresses/configure-ipv6-address)...
>
> which I guess one would query over IPv4? :-)
>
> Thoughts? Comments? Input?
>
> Thanks!
>
> Regards,
> --
> Fernando Gont
> e-mail: fernando at gont.com.ar
> PGP Fingerprint: 7F7F 686D 8AC9 3319 EEAD C1C8 D1D5 4B94 E301 6F01
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