Second attempt to get this sent to the email
list
Folks,
On
reviewing the Yahoo mailing list archive I saw an email asking why the
compatibility with 802 criterion failed to get the necessary 75% approval in
the 802.3 closing plenary session. In my view there are two reasons for
this:
1) It was stated
during the debate in the closing plenary by a study group member that no
changes to the MAC or PHY may be necessary. If that is the case then what is
the point of doing an 802.3 project? You need to give the 802.3 working
group some idea of what it is that you want to do.
2) You failed to
convince 802.1 that what you are proposing is compatible with their
switching specs. The tutorial gave the impression that the purpose of the
task force would be to standardize a mooted Firewire switch architecture in
802.1. This switch architecture requires a separate queue for RE traffic and
is required to deliver frames at precise time intervals. Predictably this
did not go down well in 802.1 and the 802.3 working group took notice of
this.
I also
have the following observations to make
i) To see RE
through as an 802.3 project you need to engage with the wider 802.3 working
group. Using a Yahoo mailing list rather than this one does not help. If you
want to know why people voted against the compatibility criterion ask on
this mailing list. The vote to set up the study group was 41 to 7 so there
is support for a task force and making changes to the 802.3 spec for RE.
Don't squander this good will.
ii) You need a
chair who is experienced in 802.3 policy and
procedures.
iii) You need to
come up with a quantitative requirement for jitter and relative latency and
justify it. I saw the figure of 10us mentioned on the Yahoo mailing list.
This is ridiculously tight. An 802.3 voter who is experienced in VOIP
pointed out to me that even 1ms is too tight when you consider that sound
only travels one foot in a millisecond. Once you have this requirement
nailed a lot else will fall into place.
iv) The sort of
thing that would make sense for a task force would be to develop a mechanism
for measuring link delay using MAC control frames so that time stamp
information could be accurately interpreted. This is within the scope of
802.3 and clearly relevant to what you are trying to achieve with
residential Ethernet.
Arthur.