Fred,
Please see inline.
2012-12-20 à 17:32, "Fred Baker (fred)" <[email protected]> :
>
> On Dec 20, 2012, at 12:54 AM, Rémi Després wrote:
>
>> Interface addresses at the link layer are specified by IEEE to be
>> universally unique.
>
> Yes, and EIU-64 is one of several seeds from which an IID can be derived.
> It's not the only one. The fact that an underlying technology provides an
> intended-to-be-globally-unique value (not that it actually *is* globally
> unique, but it is intended to be) is a happy accident, but not a requirement
> for the value we derive from it.
>
> To make assertions about IP addresses based on the EUI-64 is to impose
> requirements that don't actually exist in IP. It's a little like saying that
> concrete MUST ("are required to") be grey because the rocks we use in it
> happen to be grey; no I can have concrete of other colors if I want.
I do agree that, despite a rule exists in some RFC one can see configurations
that don't comply with it.
Consequently, "intended to be globally unique" doesn't mean "guaranteed to be
globally unique in real life", right.
This isn't a reason, however, to abandon rules that proved to be useful.
AFAIK, the rule that IIDs having u=1 must (so far) only be based on global IEEE
EUI-64 addresses is one of these useful rule not to be abandoned.
> The comment Brian is making refers to IP's requirements, which are that the
> IID used in a subnet by an interface must be unique within that subnet.
This is a clear requirement, on which I think we all agree.
It is worth noting here that satisfaction of this requirement DOES DEPEND in
part on IIDs having u=1 being actually unique.
(Reason is that RFC 4862 says (uppercase added) "IPv6 nodes are NOT required to
validate that interface identifiers created with modified EUI-64 tokens with
the "u" bit set to universal are unique".)
> If one has a physical machine with an interface that supports a dozen virtual
> machines, the requirement is not that all of the physical and virtual
> machines use IP addresses derived from the physical interface MAC address;
Well understood.
> the requirement is that they each have IIDs that are unique within the
> subnet. The obvious choice will be to use privacy addresses for the VMs,
> which will appear outside the physical machine as the one interface having
> that many IP addresses.
Agreed.
Since these IIDs will have u=0, this is neutral in the discussion on u=1 IIDs.
AFAIK, no technical and/or operational consideration remains that would prevent
the IANA registry on IIDs to be updated as follows (the 4rd range is that
proposed by Brian).
The answer returned to Softwire can then be a request to change the 4rd draft
accordingly.
+-----------------------------------------+-------------------------+
| Interface Identifier Range | Description |
+-----------------------------------------+-------------------------+
| 0000:0000:0000:0000 | Subnet-Router Anycast |
| | [RFC4291] |
| | |
| FDFE:0000:0000:0000-FDFE:FFFF:FFFF:FFFF | Reserved 4rd Unicast |
| | Addresses [RFCxxxx] |
| | |
| FDFF:FFFF:FFFF:FF80-FDFF:FFFF:FFFF:FFFF | Reserved Subnet Anycast |
| | Addresses[RFC2526] |
+-----------------------------------------+-------------------------+
Regards,
RD
--------------------------------------------------------------------
IETF IPv6 working group mailing list
[email protected]
Administrative Requests: https://www.ietf.org/mailman/listinfo/ipv6
--------------------------------------------------------------------
