> From: Charles E. Perkins [mailto:[EMAIL PROTECTED]]
[...]
> As I wrote before, but perhaps buried in other text,
> I think that IP should only be concerned about the
> "subnet-local" concept, not the "link-local" concept,
> if we are to use those terms as distinguishable concepts.
> When the link-local addresses were being first discussed,
> I don't remember any discussion that suggested that a
> "link" should have a different extent than a "subnet".
>
> It seems to me that all IP-level protocols need to
> have "subnet-local" addressing, not the newer proposed
> definition for "link-local".
It's defined today as non-routed.
You're proposing to route link-local addresses, so you're
the one with the "new proposed definition" :)
> As I tried to point out
> in my previous message, IP doesn't have any business
> messing around with details about how the subnet is
> actually constructed.
Here we disagree. A multi-link subnet router does that
(as do IPv4 ARP proxies today, for that matter).
> Thus, to restate, I believe that "link-local" addresses
> are not required to traverse the entire extent of the
> physical medium on which a subnet is defined, then they
> are useless for IP protocols.
Could not parse the above. Maybe you meant "I believe
that IF ..."?
^^
> Perhaps it would be
> better to rename these addresses (FE80::/10) to be
> called "subnet-local".
That's what your position boils down to, yes.
(I pointed this out on this list prior to last IETF.)
At this point I am undecided on this issue, other than
deciding that if fe80::/10 is not subnet-local, DAD
is cleaner than DIID.
> Do you have examples of protocols that properly use
> "link-local" addresses instead of "subnet-local"
> protocols? It seems to me that DAD, multicast,
> router advertisements, and Mobile IP all need to
> have the "subnet-local" property, and I can't think
> of any network-layer use for the non-network-layer
> definition of "link-local".
For unicast link-local addresses, I can't either right
offhand, although I can't say one might not exist.
I agree that DAD on *non-link-local* addresses needs
to have the subnet-local property, but unfortunately
DAD is currently defined using multicast scope 2
rather than 3 as it should have been. This means
workarounds are required, but this is orthogonal
to whether fe80::/10 should be left as link-local
or changed to be subnet-local.
-Dave
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