Matthias,
A few thoughts follow.
>> To have the same functionality
with Layer-2 message format we need either two different
>> Ethernet MAC addresses or two
different Ethertypes.
I would have thought that its sufficient
to have one Ethertype and a following byte
that distinguishes between distinct
message types. Since all bytes after the
Ethertype are Etheretype-dependent, this
option would be possible.
>> Are you thinking of a Layer-2
message format with IEEE 802.1 RE SG?
Yes, with only one frame type and a frame
that is the minimum (64-byte)
size.
What are the reasons for using a Layer-2
message format?
There are multiple reasons. I suspect that
a teleconference with more
participants would be more effective than
an email exchange with only
myself. I’m not in a position to
represent the entire RE SG; many more
folks are involved.
DVJ
From: Wenk, Matthias
[mailto:matthias.wenk@siemens.com]
Sent: Monday, November 28, 2005
11:54 PM
To: James, David V
Cc: john_eidson@agilent.com;
Antonova, Galina (GE Consumer & Industrial); Bill Powell ; Dave Roe; Goetz,
Franz; Nick Barendt; Silvana Rodrigues; Veselin Skendzic;
ludwig.winkel@siemens.com
Subject: AW: current state
Hi David,
for your information I send you a former
proposal on Layer-2 access. The intension of this proposal was to substitute
the IP/UDP header (not needed for Layer-2 access) by specific fields needed for
efficient hardware forwarding at Layer-2.
The result of several discussions in the
subcommittee and at the face-to-face meeting was not to support such a coding.
The group would like to change as few as possible on the existing protocols. So
we decided only to leave out the IP/UDP header and keep the payload unchanged.
With IP/UDP header IEEE1588 uses two UDP
ports to specify the processing of PTP messages. To have the same functionality
with Layer-2 message format we need either two different Ethernet MAC addresses
or two different Ethertypes. You told us that the IEEE is assigning only one
new Ethertype for a new protocol. So we need different Ethernet MAC addresses
for Layer-2 messages. We have to discuss that. Proposals are welcome.
Are you thinking of a Layer-2 message
format with IEEE 802.1 RE SG? What are the reasons for using a Layer-2 message
format?
Regards,
Matthias Wenk
Von:
James, David V [mailto:david.v.james@intel.com]
Gesendet: Montag, 28. November
2005 17:49
An: Wenk, Matthias; Antonova,
Galina (GE Consumer & Industrial); Bill Powell ; Dave Roe; Goetz,
Franz-Josef; Nick Barendt; Silvana Rodrigues; Veselin Skendzic; Winkel, Ludwig
Cc: john_eidson@agilent.com
Betreff: RE: current state
Matthias,
I observe that 1588 and the IEEE 802.1 RE
SG are looking at the same topic,
but from different perspectives.
I suspect that an additional (joint)
subcommittee meeting might be useful,
to shared experiences and thoughts.
From: Wenk,
Matthias [mailto:matthias.wenk@siemens.com]
Sent: Monday, November 28, 2005
3:14 AM
To: Antonova, Galina (GE Consumer
& Industrial); Bill Powell ; Dave Roe; Goetz, Franz; Nick Barendt; Silvana
Rodrigues; Veselin Skendzic; ludwig.winkel@siemens.com; James, David V
Cc: john_eidson@agilent.com
Subject: current state
Hi
everybody,
there
was no Layer-2 subcommittee meeting since our face-to-face "working
dinner". In my opinion there is either no meeting needed. The current
state is that the reserved field for storing the receiving time stamp inside
the frame is no more needed. So there are no Layer-2 specific fields inside the
frame.
The
proposal for Layer-2 message format is only to leave out the IP/UDP header.
This proposal needs the definition of new Ethertypes. I think it is sufficient
to discuss this at the next face-to-face.
Do
you agree with that or do you think we need an additional subcommittee meeting?
Regards,
Matthias
Wenk
____________________________________________
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Matthias
Wenk SIEMENS
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