RE: Gearbox reality check
Eric, Brad,
I am not able to discuss about OIF/SUPI interface.
What I have understand is that there is a technical limit for the
electrical GMii MAC interface to produce a 1 channel in 10 Gbps.
This because of decisions related to compactness silicon versus reliability
of operations.
Do you agree that it is decided that GMII MAC will be 4 channels of 2.5
Gbps.
Regards,
Ben beeftink
product manager Fiberoptics
Kannegieter Electronica bv
the Netherlands
-----Oorspronkelijk bericht-----
Van: Erik Trounce [mailto:erikt@xxxxxxxxxxxxxxxxxx]
Verzonden: Wednesday, June 21, 2000 3:57 PM
Aan: Booth, Bradley
CC: HSSG
Onderwerp: RE: Gearbox reality check
Brad,
Ben, does this question sound familiar?
My view of this so far is that without the WIS (i.e. UniPHY LAN
mode), data coming out on the OIF/SUPI interface is simply the PCS
output, albeit at a slightly higher rate. For example, assuming
a 16-bit OIF network interface and an XGMII MAC to PCS interface,
the clock rate on the OIF is 644.53125 MHz, and the data is 66-bit PCS
codewords, split up 16-bits at a time.
Now, if you add the XAUI interface between the MAC and PCS
which includes the 8b/10b encoding, I think you need to go even
faster on the OIF interface (805.6641 MHz!), to maintain 10 Gb/s
from the MAC. This can't be right. Are 8b/10b encoding and 64b/66b
encoding mutually exclusive? Or is the 8b/10b encoding only used
across the XAUI interface with the two XGXS interface layers
encoding/decoding the RS data (MAC sends ethernet, RS encodes as
XGMII, XGXS does 8b/10b encoding, sent across XAUI, XGXS 8b/10b
decodes, PCS receives XGMII data, performs 64b/66b encoding, etc).
Can anyone clarify?
Thanks,
Erik Trounce
In message "Gearbox reality check", Booth, Bradley writes:
>Ben,
>
>Gold star!
>
>Now, can you explain how it works without the WIS? :-)
>
>Cheers,
>Brad