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Hi Ryan,
I disagree
with some of your statements.
> By creating
fixed timeslots in the upstream you are changing the nature of
Ethernet.
> Now the
maximum bit rate of one station to burst upstream is limited to its
timeslot.
> This creates asymmetry which has never been
an explicit form of Ethernet.
Ethernet is already
defined for both full-duplex and shared media. In any shared media
network, a node will be getting a share of bandwidth (a portion of the
bandwidth). Using a time slot algorithm is one way to share, CSMA/CD is
another. Both are mechanisms to *share*
the media. So it is not correct to suggest that limiting bandwidth below
full rate has never been an explicit form of Ethernet. Ethernet is
very comfortable with shared networks historically. A new algorithm
to do this over 10 km of optical
P2MP is what is new. (By the way, are you opposed
to asymmetry in EoVDSL?)
> I believe according to the
Alloptic presentation this
would be 25 - 50 Mbps/ station.
It depends on the
timeslot size, and number of slots assigned to each ONU, and number of ONUs
on the PON. For a 1000 Mbps 1:16 PON, bandwidth per ONU is ~60 Mbps.
At the extreme, one ONU could have all time slots and all the
bandwidth. The Alloptic presentation was simplified, on
purpose, to show that one can do EPON in the PHY layer without
complexity. Timeslots, and the ability to do dynamic bandwidth
distribution with the timeslots can be discussed.
> If you
increase the latencies across the media ten fold, is it still
Ethernet?
Does Ethernet define
latency - I missed that in the spec. For EPON, there is no latency added in the
downstream. Latency can be kept to a few milliseconds in the upstream for
time critical traffic. Can you explain why this is a problem?
> The end user will perceive
a difference in service.
Maybe we should build ATM PONs with
QoS ..... just kidding.