Re: Globally Unique Link Local Addresses (Re: about violation of standards)

[神明達哉 <[e-mail]>]

At Wed, 24 Apr 2019 13:28:48 +1000,
Mark Smith <[e-mail]> wrote:

> However, the drawback of using LL addresses is that each application
> has to be written to specifically handle them via sin6_scope_id.

This is not entirely accurate.  Section 11 of RFC 4007 exists exactly
for this purpose.  And, in fact, applications like ssh can perfectly
work for a link-local destination even on a multi-link host even if
the application (ssh client) doesn't do anything special for
link-local address:

% ssh fe80::1%lo0 'echo ok'
ok

It's true that *some* applications may still need to handle link-local
addresses as a special case, though.

> I understand that one of the motivations for Link-Local addressing was
> the "dentist's office" scenario i.e. non-technical, plug and play, "it
> just works" networking. Having to have specially adapted applications
> to suit that that scenario is pretty contradictory to that goal.

I wouldn't expect a dentist to type in a textual link-local address
(or for that matter, perhaps any textual IPv6 address) anyway.  In
this context it's more about a higher level problem than
scope-awareness of the application.  It would have to use some kind of
zero-config service discovery library with sophisticated user
interface.  That "library" may have to be aware of the concept of
scoped addresses more explicitly, but the application would be more
likely to be agnostic about it.

--
JINMEI, Tatuya