Linux and ULA support and default route

Tore Anderson tore at
Thu Oct 13 09:36:13 CEST 2016

* Jeroen Massar <jeroen at>

> RA's only install the /64 and when default announced a default.
> Thus 'the rest of the ULA /48' would require a default route to be
> installed to reach that...
> When the device does not install a default route, there won't be an
> entry for anything in that /48, just the /64 and thus that space won't
> be reachable.

Not if you set the accept_ra_rt_info_max_plen sysctl to >= 48 (and the
router implements RFC 7084 L-3). As far as I know, this sysctl is 0 by
default which causes the kernel to ignore RIOs.

I believe that Windows do accept RIOs by default so that's probably why
it worked for Brian. NetworkManager user-space RA processing will also
respect RIOs by default.


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