Re: Clause 48 Questions
I agree with all your responses to Boaz.
Please submit a comment to cover your 3rd issue and thanks for pointing
out this error.
> There is a difference between the delay specified in prior drafts which was
> for MDI to XGMII and the delay specified here which is only the delay of a
> single PCS or a single XGXS. The old delay therefore included the PMD delay
> which now has a separate 512 bits round trip allocated. The editiors were
> tasked to come up with reasonable delay figures and a consistant way to
> express them for all the sublayers. The new number appeared in clause 44 of
> D2.1 in a table summarizing all the delays but clause 48 was not updated to
> match. This of course resulted in comments and the change you see in D2.3
> reflects the resolution of the comments.
> On your second point, the rules for error propagation never require an error
> to be moved back 2 columns. They only require an error in the |T| column
> that falls after the /T/ to be copied to the prior column and an error in
> the column after the |T| column to be copied to the |T| column. Therefore,
> the error propogation rules require an additional delay of 32 BT. (Remember
> that BT is bit times for the MAC bits - a column has 32 MAC data bits
> encoded into 40 code bits.)
> On your third question, I think you have found a mistake. The delay in
> clause 48 should include the PMA. That is what the entry in Clause 44
> -----Original Message-----
> From: Boaz Shahar [mailto:boazs@xxxxxxxxxxxx]
> Sent: Tuesday, March 27, 2001 8:02 AM
> To: HSSG (E-mail)
> Subject: Clause 48 Questions
> Couple of questions occurred to me while reading D2.3:
> 1) In previous drafts (I think it was D2.1), the specified delay from Start
> sampling to MDI output is 1024BT, and the delay from MDI input to XGMII
> Start is 1024BT as well (Table 48-6, D2.1).
> In D2.3 the table is missing, and the text says that the sum of the above
> delays is 1024BT. This means about half the delay for the receive and the
> transmit. Is that the intention? And if so: What is the reason for the big
> 2) Referring the recent discussion about propagating the error after the
> packet to within packet boundary: This requires two additional samples of
> the data, because sometimes you have to generate error in a column that was
> there two clocks before. This increases the delay at least in two samples in
> each lane, or 8 data bytes, or 80 BT?
> 3)What is the delay constraint for the PMA of 10GBASE-X?
Richard Taborek Sr. XAUI Sherpa Intel Corporation
Santa Clara Design Center Network Components Division
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