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Oh dear, I have opened another can of worms ;-).

2.5G is not a 10x speed, so I guess that would go down like a lead balloon
at 802,3.

However 2.5G is a current optical specification. GBICs for 2.5G exist. I
have no idea what the reach and range implications are for 2.5G v 1G, this
in not my field. Vipul should be able to shed some light on this (no pun
intended). The economics may work in favour of 2.5G. I have no idea. I'll
leave that issue to the optics people.

I would think that the (non CSMA/CD) access control mechanism that is
specified for 802.3 EFM p2mp will scale to 10G. Thereafter it would be an
economic and market acceptability argument. This doesn't mean that I want to
stop the 1G EPON work, it just means let's make it scalable to 10G and

Let's keep this thread open for debate.

I would invite Gerry Pesavento to respond please.

Best regards


-----Original Message-----
[]On Behalf Of
Sent: 12 February 2002 18:02
To: bob.barrett@xxxxxxxxxxxxxxxxxx
Subject: [EFM] [EFM-P2MP] 10G EPONs (it was MPCP: Report message)


> May be  we should be specifying 10G-EPON given that the service
> providers are  looking at 30x3 channels of HDTV per PON.
> By the time 1G-EPON is standardised it  could be too little
> too late (again).

Serious. Why not investigate this? It may look like overkill, but we should
at least understand the price/performance here. Let us see how do it fare:

- it does not need to be 1 Gbps, or 10 Gbps. Maybe 2.5 Gbps is a good
compromise for the near future.
- higher bit rate can be used to counterbalance the relative inneficiency
of the MPCP protocol. It's a diminishing return equation - the faster the
system, the less efficient it will turn out because of the fixed parameters
such as laser on/off times. A sweet spot may lie at some point.
- how do the cost increase with higher speed optics (more than 1 Gbps),
compared with a more complex (and efficient) MPCP implementation?

Did someone check this at some point over the past few months?

[Just to remind, once again: traditional Ethernet was half duplex, only
40-60% typical efficiency. It was fast enough for a long time, and *much*
less expensive than any of the alternatives. As technology evolved, it was
possible to go full duplex, and the rest is history.]

Carlos Ribeiro
CTBC Telecom