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Re: [802.3ae] XSBI/SFI4

In a message dated 8/9/2001 12:30:55 AM Pacific Daylight Time,
satya_m@xxxxxxxxxxxxxxx writes:


Can any one mail me the details of XSBI and
SFI4 interface and the differences between them.


Hello Satya,

I am the clause editor for clause 51, the optional XSBI interface.
The XSBI details are in the 802.3ae document (clause 51). The SFI-4 document
is OIF1999.102.7 which can be found on the OIF website. If you have trouble
drop me a private email and I can help you. As for the differences between
the two, here are the key ones.

1) SFI-4 has Sync_Err (mandatory) , 802.3ae has this as optional but PMA_SI
(mandatory), SFI-4 does not have this signal
2) IEEE allows for LVCMOS levels AND LVTTL levels for some of the control
3) SFI-4 has two modes for the TX and RX clocks (622MHz - mandatory and
311MHz - optional) while XSBI only has 622MHz
4) IEEE defines optional loopback modes not spec'd in SFI-4
5) XSBI supports 10.3Gb/s serial and 9.96Gb/s operations while SFI-4 is
      for only the OC192 (9.96Gb/s data rate)

There are a few other "minor" differences that can be found. The key
relationships to note between the two are
      a) XSBI is based on SFI-4
      b) XSBI target to be compatible but NOT compliant w/ SFI-4, i.e. can
            existing SFI-4 components to build a XSBI physical instantiation
      c) SFI-4 leaves a few things vauge and open ended (e.g. polarity of
            control signals  like Sync_Err) shile IEEE desires to have a bit
            definition to specs

Hope this helps. Again, feel free to email me directly for further questions
and/or clarifications.

Justin Chang
Quake Technologies, Inc