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Re: Hari




Paul,

OK, I think we're coming to terms. I argee that Hari is (part of) a PHY over
backplane copper and NOT a layer interface.

Best regards,
Rich

--

Paul Bottorff wrote:

> Rich:
>
> This looks like a reasonable design based on the architecture I've
> outlined. The architecture provides a base for understanding all the issues
> surfacing in email about Hari and provides insite on what is required to
> use Hari for general purpose applications. I still believe Hari is a PHY
> over backplane copper not layer interface.
>
> Cheers,
>
> Paul
>
> At 04:23 PM 11/23/99 -0800, Rich Taborek wrote:
> >
> >Paul,
> >
> >Boy this is taking a lot of cycles out of my MAS budget :-(
> >
> >I'm still very confused about your notion of a Translator/Bridge/Relay
> required for Hari implementations. Let me try another illustration by
> comparing 10 GbE Hari to the serial output of the GbE Ten Bit Interface
> (TBI). Note that only the transmit direction is shown for simplicity.
> >
> >
> >1 GbE, PMA (SerDes) separate from PCS
> >-------------------------------------
> >
> >                         TBI
> >+---------+          +---------+           +---------+
> >|         +---------->         | 1 serial  |         |  Medium
> >| GbE PCS | 10 lines | GbE PMA +-----------> GbE PMD +---------->
> >|         +---------->         |   8B/10B  |         |
> >+---------+ 125 MHz  +---------+ 1.25 Gbps +---------+
> >
> >
> >1 GbE, PMA integrated with PCS
> >------------------------------
> >
> >+---------+           +---------+
> >|         | 1 serial  |         |  Medium
> >| GbE PCS +-----------> GbE PMD +---------->
> >|  & PMA  |  8B/10B   |         | 1 serial
> >+---------+ 1.25 Gbps +---------+
> >
> >
> >10 GbE, PMA integrated with PCS
> >-------------------------------
> >
> >+---------+   Hari   +---------+
> >|         +---------->         |   Medium
> >| 10 GbE  +----------> 10 GbE  +------------>
> >| PCS/PMA +---------->   PMD   | 1-4 serial
> >|         +---------->         |
> >+---------+ 4 serial +---------+
> >             8B/10B
> >           3.125 Gbps
> >
> >Several 10 GbE PMDs, like GbE support the propagation of the 8B/10B coding
> over the medium. These may include Parallel Optics, WWDM and 12.5 Gbps
> Serial. However, those are PMDs and Hari is an interface. Other 10 GbE PMDs
> strip off the 8B/10B code in the PMD and recode with more efficient codes.
> These include MAS, ~10 Gbps Serial LAN PHY and the WAN PHY.
> >
> >I beg to differ about "corrupting" Ethernet layering to fit Hari in my
> previous note. No additional layers are added. I've simply added an
> optional coding and signaling function to the PMD sublayer and illustrated
> the optional serial interface (Hari) between the PMA and PMD sublayers.
> >
> >The last point in your note argues that the 16 bit parallel interface is
> very different architecturally from Hari. I have shown above that this is
> clearly not the case. In addition, Hari has the distinct advantage of <1/4
> the pins, drivers and receivers; longer trace lengths; no clock needed with
> the data; built in error control; DC balance; and special character support.
> >
> >I have no problem with supporting the 16-bit parallel interface as an
> additional optional interface between the PMA and PMD if you feel that it's
> more appropriate for specific PMDs such as the WAN PHY.
> >
> >Best regards,
> >Rich

> 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@NortelNetworks.com

  ----------------------------------------------------------

Richard Taborek Sr.   1441 Walnut Dr.   Campbell, CA 95008 USA
Tel: 408-330-0488 or 408-370-9233           Cell: 408-832-3957
Email: rtaborek@qedinc.com or rtaborek@earthlink.net