Re: Gearbox reality check
The WAN PHY layer diagram in
4, shows the WIS sandwished between the 64B/66B PCS and SUPI.
Integration is always an implementation issue. I'm not making any support
statements regarding either SUPI or the WAN PHY, you know where I stand on this
issue. I'm simply stating for the purposes of this discussion thread that the
gearbox is implementation specific to the PMA service interface. For the
proposed WDM WAN PHY, the PMA service interface is 4-bits wide and the gearbox
is 66:4. Please also note that SUPI stripes 16-bit words on each line, so
perhaps the gearbox is more appropriately defined as 66:16:4. Note also that the
SONET overhead defined in the WIS is byte (octet) aligned, whereas the SONET SPE
is 66-bit aligned, implying that the gearbox is likely to be integrated into the
"Seto, Koichiro" wrote:
> [Date: 06/19/2000 From Seto]
> I don't understand.
> When WAN PHY uses 4-lane WDM PMA (SUPI), it still uses SONET framer (WIS)
> before facing to the 4-lane interface. Are you saying that WIS would be
> inevitably integrated with 64B66B PCS?
> > Ooops!
> > I should have written 66:4 instead of 66:6 to cover the case of 66-bit frames
> > going across a 4-lane WDM PMA interface for the WAN PHY. Sorry 'bout that!
> > Best Regards,
> > Rich
> > --
> > Rich Taborek wrote:
> > >
> > > Roy,
> > >
> > > The purpose of the "gearbox" you mention is simple and straightforward.
> > > However, it should be noted that the gearbox is implementation specific
> > > to the PMA service interface. The 66:16 gearbox converts 66-bit sub-frames
> > > and slices them up into 16-bit chunks for transport over 16-bit interfaces
> > > such as the XBI proposed as a PMA service interface:
> > > http://grouper.ieee.org/groups/802/3/ae/public/may00/robinson_1_0500.pdf
> > >
> > > Other 10 GbE PHY implementations may utilize a 66:6 gearbox or no gearbox
> > > at all in the case that the PMA service interface is a 1-bit serial
> > > interface.
Richard Taborek Sr. Phone: 408-845-6102
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