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Re: Long distance links


In spite of differences, we all have one thing in common, which is to connect 
all the global Ethernet LAN sites together through WAN at the most 
cost-effective method.  LAN people are determined to extend their $28 billion 
market into the $230 billion WAN market.  So far, we are trying to achieve 
the same goal by making the conversion from LAN to WAN, simple, and low cost. 

I tried to find out where is our difference?  The difference is whether we 
should be responsible for "LAN to WAN conversion" only, or we should also 
extend our responsibility to assure the installed bases are preserved without 
added cost.  

I believe the objective is clear -- the latter one is correct.

Your proposal of "WAN compatible PHY" is to make 10GbE PHY = WAN PHY, which 
will impose 9.58..Gbps, NRZ scramble code and SONET OAM into IEEE 802.3 10GbE 
standard.  I think we like to keep IEEE 802.3 an Ethernet standard, but not a 
SONET standard. 

In order to make this "WAN compatible PHY" to talk to the rest of Ethernet 
LANs, the "LAN to WAN conversion" will take place in every individual 
Ethernet terminals, which add unnecessary cost to the installed bases. 

I am not reasoning the WAN/PHY is much more expensive than a LAN/PHY, but I 
am reasoning the unnecessary cost added to each terminals.  They should be 
tranparent from the LAN-to-WAN conversion issue -- no change. 

Why we cannot locate your "WAN compatible PHY" at only one location at the 
LAN entering point from WAN.  That will do exactly what you want to do -- 
Ethernet Frame, 9.584. Gbps, some kind of OAM to deal optical fault issues.  
I have not seen any good reason to insist that the conversion should be 
located inside the LAN. 

We need a LAN/PHY to keep 10/100/1000/10000 Mbps compatible.  We definitely 
need WAN/PHYs to interconnect all Ethernet LANs together, which the strong 
market demand will create, with or without us anyway.  I believe what you are 
proposing is that HSSG is the logical body at the right moment to create it.  
I would agree.

Therefore, we need both LAN/PHY and WAN/PHY?  


Ed Chang
NetWorth Technologies, Inc.



> Ed,
>  I have seen and heard a lot of issue about the WAN compatible MAC/PHY 
> more
>  expensive than a LAN only MAC/PHY.  Has anyone done any actual cost 
>  Having done development work before, even if it was some time ago,  the 
> ability to
>  use existing technology and chips was always less expensive for initial
>  deployment. A lower frequency signal encode and decode was always less 
> expensive
>  over the long term.  Semi-static information processing was always less 
> expensive
>  was less expensive than active information processing.  Unless it is 
>  vendors trying to protect their control and high profit margins for WAN
>  interfaces, I can not see why a WAN compatible PHY should be more 
> than a
>  LAN only PHY at the same laser powers.  I have seen nothing to support it 
> that
>  assumption.  As a customer, I would like to see the WAN comparable costs 
> the
>  LAN interfaces.  As a customer, I would like to be able to take the same 
> type of
>  interface and use it where ever my implementation architecture requires.  
> a
>  customer I would like to be able to have unmodified 802.3 frames delivered 
> from
>  any one place to any other place with the least expense, in both equipment 
> and
>  support costs.
>  Thank you,
>  Roy Bynum
>  MCI WorldCom
>  NetWorthTK@xxxxxxx wrote:
>  > Additional Comments:
>  >
>  > I think we all brought up good discussions to nail down the specifics to
>  > enabling decision making.
>  >
>  > I agreed Paul's light SONET/PHY (WAN/PHY),  which is the necessary
>  > requirement to let 10GbE extend its market share into the Global market, 
> and
>  > to become the dominant force in the marketplace.  A private GbE user in 
>  > talks to another private GbE user in another continent without slowing 
> down
>  > to 56K bps, or 112 bps, but at the similar cost, will ultimately 
>  > the Ethernet market.
>  >
>  > However, light SONET/PHY is a low-cost,  intermediate range covneter, 
> which
>  > is good enough to reach the closest SONET terminal (or DWDM).  The 
> distance
>  > could be MAN distance, or up to 40 km, which fits Roy's proposal for 
>  > OAM needs.  The light SONET/PHY data will be retransmitted; as a result, 
> it
>  > does not have to be responsible for those jitter-tolerance, jitter-
> transfer,
>  > ... requirements -- making it as cost-effective as possible.
>  >
>  > I believe FP laser can reach 40 km with some good design practices, but 
> not
>  > much of cost increase from 10 km devices.  Many LAN vendors are 
> 40
>  > km range without any big-deal, and why we make it so difficult for 
> ourselves?
>  >
>  >
>  > On the other hands, there is no reason at all that MAC/Plus should adapt
>  > anything other tahn 10.000 Gbps as Dan is screaming to all of us.  Leave 
> it
>  > as a true Ethernet for backward compatibility, and keep all Ethernet
>  > advantages.
>  >
>  > Some where in the link, the data rate has to be converted.  The light
>  > SONET/PHY is the most logical and cost-effective location to convert data
>  > rate and do framing.  We still can make it cheep and works well, because 
> only
>  > one light SONET/PHY chip is needed at the entering LAN point.
>  >
>  > I still do not see the justification of everyone has to be 9,58... , 
> instead
>  > of 10.000 and 9.58... for the sake of fairness to both LAN and WAN 
> We
>  > are an equal opportunity committee -- I believe.
>  >
>  > Regards,
>  >
>  > Ed Chang
>  > NetWorth Technologies, Inc.
>  > EChang@xxxxxxxxxxxxxxxx
>  > >
>  >