Date: Wed, 21 Jul 2021 00:20:21 +1000 From: Scott <freebsd-lists-5@thismonkey.com> To: Mel Pilgrim <list_freebsd@bluerosetech.com> Cc: freebsd-questions@freebsd.org Subject: Re: Specifying IPv6 off-link for a subnet Message-ID: <YPbbpT3fm531Od5h@thismonkey.com> In-Reply-To: <010afd33-d7e5-b8b5-229e-823aa007a045@bluerosetech.com> References: <YOMpKMgvV2zs4ZVj@thismonkey.com> <5ea688b3-79b9-8a28-0430-5a4651207ae0@bluerosetech.com> <YPTCSCcndUWY4409@thismonkey.com> <010afd33-d7e5-b8b5-229e-823aa007a045@bluerosetech.com>
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On Mon, Jul 19, 2021 at 12:40:35PM -0700, Mel Pilgrim wrote: > On 2021-07-18 17:07, Scott wrote: > > On Wed, Jul 07, 2021 at 07:43:48PM -0700, Mel Pilgrim wrote: > >> On 2021-07-05 8:45, Scott wrote: > >>> I have manually configured IPv6 on the interfaces: > >>> ifconfig_vmx0_ipv6="inet6 xx::yy prefer_source accept_rtadv -autoconf no_radr" > [...] > >>> Here's the received RA: > [...] > >>> prefix info option (3), length 32 (4): xx::/64, Flags [none], valid > >>> time 3600s, pref. time 60s > >>> > >>> Note that there is no L flag set, so the prefix is off-link. > >> > >> If set, the L flag indicates the prefix can be used for on-link > >> determination. But if the L bit is unset, the PIO isn't making any > >> assertion about the prefix being on-link or off-link. More importantly, > >> a host must not use a PIO with L=0 to conclude a prefix is off-link. > >> > >> IOW, it is correct for a host to do nothing when it receives an RA PIO > >> with no flags for an already-configured prefix. > > > > so for the case of manually addressed devices on a private vLAN/IPPL there > > must be a way to specify that the configured prefix is not on-Link. > > Yes, by not configuring that prefix. Numbering vmx0 into xx::/64 made > xx::/64 on-link by definition. > > This seems like too intuitive of an answer, though. Can you step back > and explain what you need to do at a higher level? > My need is pretty simple: to have FreeBSD servers with an IPv6 stack operating correctly on a private vLAN (IPPL). Specifically an isolated private vLAN. In IPv6 (as I understand it), this should be done by specifying that the prefix/subnet of the configured address is not on-link, and therefore should *always* use the router as the next hop. (Similar to an NBMA network). I have this working for IPv4 - which uses different mechanisms such as local proxy ARP on the router (such mechanisms do no apply to v6). Thanks
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