Le 10/04/2019 à 14:40, Ole Troan a écrit :
You said: if OCB is still 48bit, and if there is bridging
OCB-Ethernet, then no reason to be different than rfc2464.
I said: OCB is still 48bit, but there is no bridging OCB-Ethernet.
The conclusion is: there is reason to be different from RFC 2464.
Why?
Now, you give a different conclusion.
Excuse me, I would like to clarify this please?
Clarify what?
You said if OCB-Ethernet bridging then no need of update. Then you
concluded differently. That needs clarification.
That a link-layer that looks an awfully lot like Ethernet
It looks an awful lot like Ethernet, but it can not be bridged to it.
The 'brctl' and 'brconf' software issue errors when trying to link OCB
interface to Ethernet interface.
[That a link-layer that looks an awfully lot like Ethernet] should not
follow the 64-bit boundary and the definition of the link-local
address mapping of rfc2464? Section 4.5.1 is already clear on that.
If OCB can not be bridged to Ethernet then OCB interfaces are free to
have a 65bit IID, without fearing lack of interoperability to an
Ethernet interface with 64bit IID. The IP forwarding does not care
about IID length, and there is no bridging.
I think the only thing we are asking you is to change the following
paragraph:
OLD: A subnet is formed by the external 802.11-OCB interfaces of
vehicles that are in close range (not by their in-vehicle
interfaces). This subnet MUST use at least the link-local prefix
fe80::/10 and the interfaces MUST be assigned IPv6 addresses of type
link-local.
NEW: A subnet is formed by the external 802.11-OCB interfaces of
vehicles that are in close range (not by their in-vehicle
interfaces). A node MUST form a link-local address on this link.
Makes sense, I will add it.
Then somebody will ask what is the prefix length of the LL prefix on
OCB? What reference should I give to the person asking?
The reference is RFC2464 that says 64bit IID. But that is for Ethernet
and EThernet can not be bridged to OCB.
Not quite sure what value that paragraph adds in the first place. You
could probable remove it.
The value in mentioning /10 is that it works on OCB (it works also on
Ethernet but not on all OSs, and so it may risk violating a section).
Alex
Cheers, Ole
Alex
Le 10/04/2019 à 12:28, Ole Troan a écrit :
Alexandre, Right, so it doesn’t sound like you have any reason to
be different from RFC2464. Just reference or copy that text
(section 5, rfc2464). Ole
On 10 Apr 2019, at 11:22, Alexandre Petrescu
<alexandre.petrescu@xxxxxxxxx> wrote:
Le 10/04/2019 à 11:04, Ole Troan a écrit :
"At least" does not mean "the value should be at
least 10" in that phrase.
Do you think we should say otherwise?
To me there is nothing in the actual text to tell me
that "at least" qualifies the "/10". I think you could
rephrase as "This subnet's prefix MUST lie within the
link-local prefix fe80::/10 ..."
However, see Jinmei's messages about conformance with
RFC 4291.
I think there might be unexpected side effects from
using an address like fe80:1::1. What if some code uses
matching with fe80::/64 to test if an address is
link-local? I agree that would be faulty code, but you
would be the first to discover it.
Indeed. If you absoultely must cut and paste text from
2464:
YEs, that is how we started. We cut and paste from 2464.
5. Link-Local Addresses The IPv6 link-local address
[AARCH] for an Ethernet interface is formed by appending
the Interface Identifier, as defined above, to the prefix
FE80::/64. 10 bits 54 bits 64
bits
+----------+-----------------------+----------------------------+
|1111111010| (zeros) | Interface Identifier |
+----------+-----------------------+----------------------------+
I presume there is support for bridging 802.11p and other 802.3 links?
In the IP-OBUs that I know there is IP forwarding between
802.11-OCB (earlier 802.11p) and 802.3, not bridging.
In some IP-OBU (Internet Protocol On-Board Unit) some non-OCB
interfaces are indeed bridged. E.g. the Ethernet interface is
bridged to the WiFi interface; that helps with DHCP, tcpdump
and others to see one a single - bridged - interface.
Bridging may be, but it is not a MUST. There is no necessarily
any bridging between the 802.11-OCB interface and other
interface, neither bridging between the multiple 802.11-OCB
interfaces that might be present in the same computer.
Do you assume bridging of 802.11-OCB interface to Ethernet
interface is always there?
Note: I also heard many comments suggesting that EAL is akin to
'bridging'. I do not know whether you refer to that
perspective. If yes, we can discuss it separately.
Alex
[...]
And that the MAC address length of this link type is also
48 bits?
YEs, the length of MAC address on 802.11 mode OCB is also
48.
If the two assumptions above hold, then I see zero
justification for pushing the 64 bit boundary in this
draft.
Let me try to understand the first assumption.
Ole
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