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RE: PMD discussion

Hi Rich, 

I think that the confusion comes from the discussion of the standard versus
one possible implementation.  It seems like you are trying to have one
implementation as the standard.

If I follow your arguement, then Serial 1550nm optics may meet the distance
objectives in the same way your LAN PHY + WIS may meet the WAN PHY
objectives.  However, these are not necessarily optimized for their
respective applications.  

Your LAN PHY + WIS (with the WIS being in the transport equipment) is
putting a long interface (ie SERIAL LAN PHY) between the PCS and WIS (stack
diagram on Pg 4 of

One may argue that this meets the objectives but it is not necessarily
optimized for applications that run over SONET infrastructure or "Optical
Network" equipment (which are actually based on SONET).

There may be options to where the WIS could be placed.  However, the
standard should not be such that it dictates where.  Vendors may achieve
Howard's Nirvana - LAN PHY, WIS, and SERDES in one device (p16 of
frazier_1_0300.pdf link enclosed below). 



-----Original Message-----
From: Rich Taborek [mailto:rtaborek@xxxxxxxxxxxxx]
Sent: Monday, May 29, 2000 2:27 PM
Subject: Re: PMD discussion


I agree with you. However, I believe that we are loosing sight of the
goal of the WAN PHY: Compatibility with the SONET/SDH infrastructure. 

I'd like to address a comment regarding our objectives that was made during
Ottawa meeting on several occasions: It was said that a LAN PHY with a WIS
SONET/SDH compatibility) does not meet the HSSG objectives. I'm having
understanding why a solution which "exceeds" the objectives, and is highly
likely to be lower in cost, is inferior to one which "meets" the objectives.

The specific objective in question is as follows:

Define two families of PHYs
- A LAN PHY, operating at a data rate of 10.000 Gb/s
- A WAN PHY, operating at a data rate compatible with the payload rate of
OC-192c/SDH VC-4-64c

It has been proposed, and there is general agreement (i.e. lack of any other
proposal) that the WIS, a layer 1 (PHY) sublayer is used to encapsulate
packets, using 64B/66B for a PCS, for transport over SONET/SDH. The latest
relevant proposals from Ottawa are:

The location of the WIS in a WAN PHY can be illustrated as follows:

    +-----+    +-----+        +-----+    +-----+ 
--->|     |--->| PHY |------->|     |--->|SONET|
    | MAC |    |     | medium | PHY |    |  \  |
<---|     |<---|(WIS)|<-------|     |<---| SDH |
    +-----+    +-----+        +-----+    +-----+ 
  controlled)   |<--- WAN PHY ---->|
Alternatively, the location of the WIS in a LAN PHY can be illustrated as

    +-----+    +-----+        +-----+    +-----+ 
--->|     |--->|     |------->| PHY |--->|SONET|
    | MAC |    | PHY | medium |     |    |  \  |
<---|     |<---|     |<-------|(WIS)|<---| SDH |
    +-----+    +-----+        +-----+    +-----+ 
  controlled)   |<--- LAN PHY ---->|

Note that the WIS function simply moves to the right (towards SONET/SDH) and
same PHY, a LAN "UniPHY" if you will, may be used to achieve full SONET
compatibility. MAC/PHY rate control is not issue between the two methods. I
understand how to implement it either way.

Please point out the flaw(s) with the LAN UniPHY in supporting Ethernet over
SONET. Is it that there is a unwritten requirement for a WAN PHY to support
payloads other than Ethernet over SONET/SDH? I'd call any such requirements
of the scope of IEEE 802.3.

Best Regards,

jay.hoge@xxxxxxxxxxxxxx wrote:
> In order for the WAN PHY to do its job, it cann't use a line code or else
> the data rate will exceed that of OC-192. Scrambling anyone?
> Jay
Richard Taborek Sr.                 Phone: 408-845-6102       
Chief Technology Officer             Cell: 408-832-395 
nSerial Corporation                   Fax: 408-845-6114
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