|Thread Links||Date Links|
|Thread Prev||Thread Next||Thread Index||Date Prev||Date Next||Date Index|
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)
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.
From: Wenk, Matthias
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?
James, David V [mailto:firstname.lastname@example.org]
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.