[RE] Compatibility with 802 and why the study group is not yet a task force
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.