At Mon, 15 Apr 2019 09:42:53 +0200,
Alexandre Petrescu <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:
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
--
JINMEI, Tatuya
Alexandre Petrescu <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:
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
--
JINMEI, Tatuya
