RE: [802.3ae] XSBI Bit ordering
Satya:
The bit ordering at the PMA service interface (Clause 51) is the same for
LAN and WAN PHY cases. A bit relabelling is done *before* it hits the PMA
interface for the WAN PHY case, as you point out.
What may be a bit confusing is the way there are two relabelling in the
"stack" when you have a WAN PHY with a XSBI interface, but this is to ensure
consistency at the PMA service interface (i.e., identical bit ordering for
LAN and WAN PHY cases).
There was a significant and lengthy discussion on this matter on the
reflector (see: http://www.ieee802.org/3/10G_study/email/msg04584.html";),
because of the importance of maintaining compatibility between Ethernet and
SONET at the 16 bit interface, and the current relabelling within Clause 51
is the result of this compromise solution.
Cheers,
Dave
------
David Kabal
Sr. Technology Planner
Picolight
e-mail: david.kabal@picolight.com
Main: 303-530-3189 x272
Direct: 303-527-7498
Fax: 303-527-4961
> -----Original Message-----
> From: owner-stds-802-3-hssg@majordomo.ieee.org
> [mailto:owner-stds-802-3-hssg@majordomo.ieee.org]On Behalf Of satya
> Sent: Wednesday, September 12, 2001 3:38 AM
> To: stds-802-3-hssg@ieee.org
> Subject: [802.3ae] XSBI Bit ordering
>
>
> hi all,
>
> While going through the IEEE 802.3 ae Draft 3.1
>
> Clause 51 describes XSBI mapping as following
>
> For the XSBI instantiation of the PMA service interface, the
> mapping of
> bits between the PMA service interface and the XSBI physical interface
> is defined for transmit in Table 51 2 and for receive in
> Table 51 3.
> Table 51 2 Transmit bit mapping
>
>
> Name Bit numbers
>
> PMA service tx_data-group 0 1 2 3 4 5 6 7 8
> 9 10 11 12 13 14 15
> interface
> ^
> ^
>
>
> |
> |
> XSBI physical xsbi_tx 15 14 13 12 11 10 9 8 7
> 6 5 4 3 2 1 0
> interface
>
> Table 51 3 Receive bit mapping
>
> Name
> Bit numbers
>
> PMA service rx_data-group 0 1 2 3 4
> 5 6 7 8 9 10 11 12 13 14 15
> interface
> ^
> ^
>
> |
> |
> XSBI physical xsbi_rx 15 14
> 13 12 11
> 10 9 8 7 6 5 4 3 2 1 0
> interface
>
>
> Clause 51 does not say bit mapping will be done
> only for LAN or WAN or for both.
>
>
> But in Clause 49
>
>
> The ordering of bits and octets for the case when no WIS is present
> between the PCS and PMA is shown in Figure 49 2
> with no bit reordering meaning that PMA LSB is mapped to LSB of PCS.
> But when WIS is present bit order change is shown in Figure 49-3.
>
>
> ----------
> Question
> ----------
>
> Do we need to change the bit ordering for both LAN and WAN
> application?
> If it is only for WAN i.e., with WIS only then Clause 51 has to be
> updated with this point in the XSBI description.
>
> Please correct if i am wrong or miss understood.
>
> Thanks
> satya
>
>
>
>
>
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