Le 04/05/2015 03:11, Michael Richardson a écrit :
Alexandru Petrescu <[email protected]> wrote:
>> This proved useful for Ethernet; too much maybe since we were fooled
>> into extending IP over Ethernet to Wi-Fi...
> I take advantage of this note from Pascal, to extend a parenthesis.
> IPv6-over-Ethernet is specified in RFC2464.
> IPv6-over-WiFi is not specified. There are differences in the formats
> of headers between Ethernet and WiFi, noticed by wireshark.
Actually, that's not true.
Wireshark notices the difference because wireshark (and whatever OS you are
running it on), provides an interface that lets you see below the Ethernet
compatibility layer.
Right. And if so it means that there is an Ethernet compatibility
layer. And that Ethernet compatibility layer (supposedly making 11b
layers look like Ethernet, to IP) is not specified as far as I know. Is
there a specification of that Ethernet compatibility layer?
+--------------------+-------------+-------------+---------+
| 802.11 Data Header | LLC Header | IPv6 Header | Payload |
+--------------------+-------------+-------------+---------+
^
|
802.11-to-Ethernet Compatibility Layer
|
v
+---------------------+-------------+---------+
| Ethernet II Header | IPv6 Header | Payload |
+---------------------+-------------+---------+
Some years ago (before wireshark), if you ran tcpdump on a wifi interface,
you would see only ethernet, as the ethernet-compatibility part of 802.11
was all that was exposed to the operation system by the firmware in the
wifi card. In Linux, it's only since much of the 802.11 logic moved from
the firmware in the PCMCIA card into the Linux kernel that it became possible
to see what was below 802.3.
I didnt know that.
This is akin to seeing IPv6, but not 6lowpan below.
I agree.
Speaking of which - we do have a specification of what 6lowpan
adaptation layer does.
Alex
--
Michael Richardson <[email protected]>, Sandelman Software Works
-= IPv6 IoT consulting =-
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