Re: Roy's thread
For the case where the PMD simply repeats the Hari interface and retains the 4 channels as independent I'd rather refer to this PMD option as a multi-channel PMD. We've already heard proposals on several of those:
1) Parallel optics: 4 channels on 4 fibers
2) CX multi-channel: 4 channels on 4 coax's
3) WWDM: 4 channels on 1 fiber
My point is that there's more to these PMDs than just Hari and I'd rather limit Hari to being an interface rather than an interface AND a PMD.
Bill Woodruff wrote:
> Roy & others,
> If we want to do a simple serial PHY, then we need a simple parallel interface. An OIF style x16 interface is good, as would be a TBI (ten bit interface). In either case we have a parallel word with clock. While this is simple, it has two issues that the Hari interface avoids; the high pin count and the tight skew requirments.
> Just because Hari exists does not make the simple x16 or x10 interface go away. Chips and modules with these interfaces either do, or can, exist, and equipment people can easily use them.
> Meanwhile the Hari world may also want a simple Hari repeater. Such a device would be a simple 'eye opener' for a media that retains the 4 channels as independent. Such a repeater opens the discussion of Hari as a PHY interface, which up till now has not been well discussed.
> Regards, Bill
> I'm not sure what gave you the idea that Hari was favorable to serial PHYs. I do know that
> it is not favorable to anything other than the legacy fiber channel 8B10B LAN PHY. Hari is
> NOT a PHY neutral device interconnect. Some LAN vendors have very huge boards and they want
> something that will support their 8B10B encoding over the distance of their board, and also
> the back plane if needed. By introducing Hari as the standard for device interconnect
> between the PMA and the PMD, they are specifically, and possibly knowingly, hampering the
> development of the agreed on WAN PHY. There is no mechanism for rate controlling over
> Hari. This is in violation of the agreed objective in this regard. Hari is an attempt by a
> specific camp to control the development of 10GbE and limit development of anything other
> than the 10.0 only rate PHY.
> As you will remember, I called the presenters and floor on the issue of what Hari really
> was. It was admitted that it was a LAN extension interconnect by the individual that
> responded. For those of us that are attempting to bring 802.3 into the 20th century by
> making a truly ubiquitous MAC, we have been astounded by the brazen push of this
> "interconnect". Chip makers will confirm that Hari specifically makes the WAN PHY
> extremely difficult to implement. Since Hari truly is not common to all of the PHYs as
> specified in the objectives, I suggest that it be withdrawn from consideration as part of
> the 10GbE standard.
> Thank you,
> Roy Bynum
> Bill Woodruff ph: 805 496-7181 x14
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- From: Carlos Alessander Costa Alves (Pos-Graduacao DSC)