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Re: [802.3_EPOC] short term ad hoc committee on mulitple modulation profiles until January interim

Eugene-

On 512//12 12:47 PM, Dai, Eugene (CCI-Atlanta) wrote:

A side topic, if history tell us something,  the Ethernet originally came out as a best effort protocol, at the time there were much ones that took  more factors into consideration for better QOS, for example token ring, ATM, etc., where are they today?


I would like to add my 2 cents worth to your point.
It is true that Ethernet of yore was a best effort protocol. What's more, wireless LANs are even more of a best effort, low expectation process.
It had some other things going for it at the same time. Specifically, 10 Mb/s Ethernet had an added level of robustness because there was no saved state in the Physical Layer from either packet to packet or station to station. Token Ring had problems in this area.
The problem that we have to face is that the fully evolved Ethernet of today has done lots of things to make it look like a reliable protocol that can be used for passing timing information.
Fortunately some of the market expectations for network performance have been lowered by WiFi but there the industry has worked quite hard to spread peanut butter over those challenges.
Realistically, the channel we have available to us for EPoC lies between the P2P twisted pair/fiber and the open air channel of WiFi. Because that is actually the case it is not clear to me that a PHY only project in 802.3 (as currently is the case for this project) is the right way to go here. The questions that need to be laid explicitly on the table would be something like: 

   - Is the combination of the 802.3 and the EPON MAC the right media
   access controller for the transmission quality of the channel that
   we are addressing?
   - If the project were going to ask for changes to the above, what
   would they be and why?
   - What is there that can be taken from wireless technology to make
   things better for EPoC?

I hope all of this is useful food for thought.

Geoff Thompson

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