RE: Gearbox reality check
8b/10b is mutually exclusive of 64b/66b. The data out of the MAC is 8b/10b
encoded for transmission across the XAUI interface, it is then decoded at
the other end and re-encoded into 64b/66b by the PCS logic.
Clear as mud?
From: Erik Trounce [mailto:erikt@xxxxxxxxxxxxxxxxxx]
Sent: Wednesday, June 21, 2000 8:57 AM
To: Booth, Bradley
Subject: RE: Gearbox reality check
Ben, does this question sound familiar?
My view of this so far is that without the WIS (i.e. UniPHY
mode), data coming out on the OIF/SUPI interface is simply
output, albeit at a slightly higher rate. For example,
a 16-bit OIF network interface and an XGMII MAC to PCS
the clock rate on the OIF is 644.53125 MHz, and the data is
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
faster on the OIF interface (805.6641 MHz!), to maintain 10
from the MAC. This can't be right. Are 8b/10b encoding and
encoding mutually exclusive? Or is the 8b/10b encoding only
across the XAUI interface with the two XGXS interface layers
encoding/decoding the RS data (MAC sends ethernet, RS
XGMII, XGXS does 8b/10b encoding, sent across XAUI, XGXS
decodes, PCS receives XGMII data, performs 64b/66b encoding,
Can anyone clarify?
In message "Gearbox reality check", Booth, Bradley writes:
>Now, can you explain how it works without the WIS? :-)