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Re: I/F locations


I agree, the two demarcations are XSBI and XAUI.  SUPI is not an interface 
as standardized by IEEE. Instead SUPI supports the 10GBASE-LW4 by attaching 
WWDM to and XSBI interface. The 10GBASE-LW4 WWDM is supported attached to 
XSBI using SUPI, while the 10GBASE-LR4 WWDM can only be supported by 
implementing clause 48 and cannot attach to XSBI.

Though late for this discussion, it is possible to extend SUPI to allow 
WWDM attachment to the LAN 64b/66b encoder over XSBI. This has three 
advantages: 1)it means all optic modules and modes could be supported using 
a XSBI interface; 2)the transmission frequency of the 10GBASE-LR4 would be 
reduced from 3.125 MHz per lane to 2.578125 MHz per lane; 3)we end up with 
a single 64b/66b PCS layer for all interfaces. Using this scheme XSBI could 
support all optic module types. In addition, the XAUI option would also 
support all types.



At 01:35 PM 12/1/2000 -0800, Speers, Ted wrote:

>         I realize this is an implementation question, but is there a likely
>demarcation point between the transceiver module and the MAC.  It's hard to
>sort out a lot of these discussions (LSS, XAUI/SUPI, etc.) without have this
>in proper context.
>         Possible points of demarcation would seem to be either the XAUI or
>the XSBI interfaces.  I've seen presentations suggesting both.
>         It seems that a break at the XSBI would offer the most in terms of
>end-user flexibility and economies of scale for both the users and the
>vendors ... with one exception, 10GBASE-X4 would be left out in the cold
>because, as far as I can tell, there is no way to implement the standard
>across an XSBI.
>         Ted Speers
>         Strategic Marketing
>         Actel

Paul A. Bottorff, Director Switching Architecture
Enterprise Solutions Technology Center
Nortel Networks, Inc.
4401 Great America Parkway
Santa Clara, CA 95052-8185
Tel: 408 495 3365 Fax: 408 495 1299 ESN: 265 3365
email: pbottorf@xxxxxxxxxxxxxxxxxx