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Re: [802.3ae] D3.1 Clause 45 and Clause 48 potential inconsistencies


Boaz Shahar wrote:
> Hi there,
> I would like to clarify certain things regarding LF, RF and Link Status:
> 1.Status bit 5.1.7 suppose to to be set by the transmitter if it detects a
> LF sequence in its input OR set by the receiver if it detects LF in its
> inputs? I think it is NOT set if the receiver detects inter lane miss
> alignment condition (That is, it is not set by the receiver if the receiver
> GENERATES LF as opposed to DETECTING LF). Is that so?

I don't think so. Bit 5.1.7 says it is an "OR" function of bits
5.8.11 and 5.8.10. The first sentence of the 5.8.11 definition
says that this bit "indicates that the DTE XS has detected a
local fault condition on the transmit path". Also, the RS never
generates the LF sequence so the DTE XS transmit path can never
see the LF sequence. The first sentence of the 5.8.10 definition
says that this bit "indicates that the DTE XS has detected a
local fault condition on the receive path". I don't see any
mapping from the local fault conditions in clause 48 to either
of these bits. This should probably be fixed with a comment of
some sort.

> 2.The term "DETECT LF" stands for detecting LF sequence in the input to a
> certain function? If a receiver detects miss alignment, and generates LF as
> a result, it is not said to be LF DETECTION event?

I disagree. A receiver that is not in sync or alignment is
certainly detecting a local fault. The definition for the DTE
XS transmitter is implementation specific. Recall that transmit
is in the opposite direction for the PHY XS as it is for the
DTE XS or the 10GBASE-X PCS.

> 3. Status bit 5.8.11 detects LF on the transmit path of the DTE-XS. That is,
> set by the transmitter when it detects an LF sequence in its input in the
> DTE-XS. Bit 4.8.11 does the same for the PHY_XS. But here, transmit path
> means that the PHY-XS XAUI Receiver has to set this bit. So, according to
> the current definition, depending on this XGXS function, PHY-XS or DTE-XS,
> this bit is set by different modules in any of the cases.

This was what I was trying to say above. However, these bits
are not set when upon detection of LF sequences, only when the
data path is not yet operational. When the data path is operational,
LF sequences are simply forwarded along without any mention to
management until they get to the RS where they are noted.

> 4.The same is true  for bits 5.8.10 vs. 4.8.10
> It would be better to define:
> 5.8.11 as Tx path LF Detection for DTE-XS
> 4.8.11 as Rx path LF Detection for PHY-XS
> 5.8.10 as Rx path LF Detection for DTE-XS
> 4.8.10 as Tx  path LF Detection for PHY-XS
> BTW this method works in all other cases of symmetrical functionality
> between PHY-XS and DTE-XS because it saves a MUX in the implementation, and
> more consistent.

This issue has been discussed before and the draft reflects
how it was settled. If you want to raise the issue again, you'll
have to submit a comment against the next draft.


> CLAUSE 48 Question
> Section defines local_fault as follows: "A local fault condition
> is recognized by the PCS whenever align_status=fail". Combining this
> definition with those in clause 45 can lead to the erroneous conclusion that
> the events "Link Status Fail" and "Local fault detection" are identical. So
> I think it should be changed either in 45 or in 48 (Unless this is really
> the intention).
> Best regards,
> Boaz

Benjamin Brown
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