Le 15/04/2019 à 21:02, 神明達哉 a écrit :
At Mon, 15 Apr 2019 09:42:53 +0200,
Alexandre Petrescu <alexandre.petrescu@xxxxxxxxx
<mailto:alexandre.petrescu@xxxxxxxxx>> wrote:
> That RFC4291 section 2.1 says:
> > All interfaces are required to have at least one Link-Local unicast
> > address (see Section 2.8 for additional required addresses).
>
> Sidenote: I think the loopback interface does not have a link-local
> address. Probably it is not all interfaces that must have at least
one ll(
Indeed, there's some subtle point here. RFC4007 somewhat tries to
clarifies it:
Well, RFC4007 predates RFC4291, so it is little meaningful to say it
clarifies it.
Maybe we can say that RFC4291 must be updated given all these issues.
The IPv6 unicast loopback address, ::1, is treated as having link-
local scope within an imaginary link to which a virtual "loopback
interface" is attached.
that is, (with the assumption that the loopback interface is
configured with ::1) the loopback interface does not (necessarily)
have an 'fe80' address, but it still has a link-local scope address.
If and when 6man resumes the work of rfc4291bis we should probably
make this clarification.
BTW, whether a loopback interface has an fe80 address is actually
implementation dependent. BSDs usually assign ::1 on a loopback
interface while also generating an fe80 address on it:
% ifconfig lo0
lo0: flags=8049<UP,LOOPBACK,RUNNING,MULTICAST> metric 0 mtu 16384
options=600003<RXCSUM,TXCSUM,RXCSUM_IPV6,TXCSUM_IPV6>
inet6 ::1 prefixlen 128
inet6 fe80::1%lo0 prefixlen 64 scopeid 0x2
Ah? It self-forms that fe80 address without a sysadmin requesting it?
In other OSs like linux, windows, there is no fe80::1 unless the
sysadmin adds it.
In that sense, this is an additional reason (together with the
RFC4291-violating fe80:1::1 potentially breaking in BSD) to think that
RFC4291 and co. are mostly for BSDs.
This is not a happy situation to be in.
Alex
--
JINMEI, Tatuya
