Re: 4-8b/10b encoders or 1?
Satish Sathe,
The short answer is Option 2. There is one 8B/10B encoder per XAUI
lane.
Hope this helps,
--Don
At 03:00 PM 8/8/00, Sathe@xxxxxxx wrote:
>Hi Rich,
> I was not sure how 8B/10B encoding is to be done for the XAUI interface.
>Please refer to your presentation from the July 00 plenary:
>
>http://www.ieee802.org/3/ae/public/jul00/taborek_2_0700.pdf
>
>Going from the XGMII interface to the XAUI interface, which (if any) of the
>following
>is correct?
>
>Option 1: The 32 data bits are converted to a byte stream, then fed to the
>8B/10B
>encoder. The output of the 8B/10B encoder is then spread across the 4 XAUI
>lanes, starting with lane 0.
>
>XGMII[31:24], XGMII[23:16], XGMII[15:8], XGMII[7:0] // 32 bit XAUI i/f
> \ /
> ---------------------------------
> |
> XGMII[31:24] // data muxed into a byte
>stream
> XGMIII[23:16]
> XGMII[15:8]
> XGMII[7:0]
> |
> 8B / 10 B encoder
> |
> __________________
> / \
> EOUT[9:0], EOUT[9:0], EOUT[9:0], EOUT[9:0] // 10 bit output of encoder
>
>
// striped across 4 lanes
> | | | |
> XAUI Lane 3 XAUI Lane 2 XAUI Lane 1 XAUI Lane 0
>
>
>Option 2: The 4 bytes of the XGMII interface are sent to 4 separate 8B/10B
> encoders (conceptually), each operating on one of the 4 bytes.
>The output of each 8B/10B encoder is then sent to one of the 4 XAUI lanes.
>
> XGMII[32:24] XGMII[23:16] XGMII[15:8] XGMII[7:0] // the
>XGMII interface
> | | |
>
|
> 8B/10B 8B/10B 8B/10B 8B/10B // 4
>separate encoders
> | | |
>
|
> XAUI Lane 3 XAUI Lane 2 XAUI Lane 1 XAUI Lane 0
>
>
> I believe Option 2 results in better 0-1 distribution per lane. My
>appologies if this has already been clarified before.
>Regards,
>
>Satish Sathe
>Ample Communications, Inc.
>4034 Clipper Court,
>Fremont, CA 94538
>ssathe@xxxxxxxxxxxxx