Le 10/04/2019 à 15:44, Pascal Thubert (pthubert) a écrit :
Hello Ole:
Better remove, it is wrong anyway.
Pascal, fe80::/10 is not wrong, because:
- using fe80::/10 on OCB works ok.
- using fe80::/10 on Cisco, linux and openbsd works ok.
- IANA allows fe80::/10 for link-local addresses.
Why do you think fe80::/10 is wrong?
Because it is transitive, the description extends the so-called
subnet step by step to a potentially large number of cars such that
there is no broadcast domain that covers them all.
Pascal - the extension of OCB subnets happens with IP routing
(forwarding between IP OCB interfaces), not with bridging. The IP
routing does not forward link-locally scoped IP packets.
There is indeed no single broadcast domain that covers them all. But
there is potentially a multicast scope that could cover them all. I
never tried it, but I guess it may be necessary.
There is no single broadcast domain for all these numerous cars in a
convoy also because each car uses not one OCB interface but three OCB
interfaces, each situated in a distinct IP subnet.
If there is no broadcast domain and no multicast emulation like a BSS
does, how can we run ND? Yes, it works with 3 cars in a lab.
If it is ironic...
Between each pair of cars (or triplet of cars some times) there is a
distinct IP subnet; that IP subnet links the front bumper of one car to
the rear bumper of the other car (or the rear of a car to two fronts of
the other two cars, if in triangle formation). These IP subnets support
well IPv6 and ND works ok.
It works with 3 cars on track, not just in the garage. They form linear
convoy, or triangle formation some times.
The description looks like it is confused with the MANET / 6LoWPAN
concept of link, whereby my link joins the collection of nodes that
my radio can reach.
No, there is no confusion in writing. There is no confusion in
experimenting.
There may be confusion in reading.
We do not use MANET protocols neither 6LoWPAN protocol, nor their
concepts of links, nor 802.15.4. They are valuable in other contexts.
Alex
All the best,
Pascal
-----Original Message----- From: Ole Troan <otroan@xxxxxxxxxxxxx>
Sent: mercredi 10 avril 2019 20:41 To: Alexandre Petrescu
<alexandre.petrescu@xxxxxxxxx> Cc: Pascal Thubert (pthubert)
<pthubert@xxxxxxxxx>; ietf@xxxxxxxx; its@xxxxxxxx;
int-dir@xxxxxxxx; draft-ietf-ipwave-ipv6-over-
80211ocb.all@xxxxxxxx; Brian E Carpenter
<brian.e.carpenter@xxxxxxxxx> Subject: Re: [Int-dir] Intdir early
review of draft-ietf-ipwave-ipv6-over- 80211ocb-34 - 'conforming
IPv6' - fe80::/10 vs fe80::/64
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? 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.
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.
Not quite sure what value that paragraph adds in the first place.
You could probable remove it.
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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