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Re: PCS Tx Diagram (Clause 48)


See my responses below:

Boaz Shahar wrote:
> Rich,
> Couple of remarks about the transmit state machine in D1.1:
> Figure 48-7: Tx Source State Machine
> 1.Sending /A/ or /K/ as the first column in the IDLE pattern should be done
> with probability ~0.5 for each. So, it seems enough to choose each of them
> based on the value of code_sel (code_sel=1: Send A, code_sel=0: Send /K/).
> Thus, I think that the qualification by A_CNT_0 should be eliminated.

Qualification by A_CNT_0 is required to insure that ||A|| is sent with a
minimum spacing. In the case of a short normal or erred packet, A_CNT_0
qualification prevents the issuance of ||A|| with less than the minimum
required spacing.
> 2.The path from the "SEND_K" box to the "SEND_DATA" box means that there
> might be an IDLE pattern which is composed from a single /K/ column? I think
> that this branch should not appear. The "B" point should always be the next
> one, because it is associated with the first /R/ column that must exist in
> the IDLE pattern

That path covers the case of the anything other than Idle coming over
the XGMII/RS. It will be sent as is.

> Figure 48-8 PCS transmit idle and Signal state diagram
> 1.A general remark: When a SIGNAL event occurs, the machine which is
> generating code_sel and A_CNT_0 are freeze? I'm asking that because if it
> not so, then it may happen that the A_CNT_0=1 event occurs exactly when
> TX=SIGNAL occurs. If this happens, then the /A/ column is not transmitted:
> Instead, the Encode(SIGNAL) is transmitted.

Yes. This is correct. SIGNAL may occur anytime. Please note that SIGNAL
and SEQUENCE are not part of the P802.3ae Baseline proposal set and I
included then for two purposes:

1) Show how these 10 Gigabit Fibre Channel Ordered-Sets operate and
interact with all 10GE Ordered-Sets. A 10GFC liaison request is to only
reserve 10GE code space for these Ordered-Sets but not include them in
P802.3ae state diagrams.

2) Show how these Ordered-Sets may be used to transport Link Status
information per taborek_2_1100.pdf
> 2.Whats the motivation behind SIGNAL event: Is this the RF? If so, it is not
> coordinated with your presentation in Tampa, where you show the RF comes
> always after the /A/ column

See above for SIGNAL history. The protocol we came up with in Tampa for
Link Status is neither SIGNAL nor SEQUENCE. I've coined a name for the
protocol: PULSE, to differentiate it from SIGNAL and SEQUENCE. Note that
virtually all the Link Status work occurred in Tampa whereas D1.1 was
available about a week prior to Tampa. This should account for any

Best Regards,
> Figure 48-9: Transmit Sequence
> 1.If I understand whats written there-You send a sequence until A_CNT_0=1,
> then you send /A/, then you send pseudo random /K/ /R/ pattern until
> A_CNT_0=1 again, and then you transmit the sequence again. What is the
> motivation?
> Thx.,
> Boaz


Best Regards,
Richard Taborek Sr.                 Phone: 408-845-6102       
Chief Technology Officer             Cell: 408-832-3957
nSerial Corporation                   Fax: 408-845-6114
2500-5 Augustine Dr.        mailto:rtaborek@xxxxxxxxxxx
Santa Clara, CA 95054