[802.3ae] RE: Clause 49: S Type Definition and PCS Receive State machine( Figure 49-13)

["Sumit Das" <sdas@xxxxxxxxxxxx>]

Hi Tuan
  I think it should be treated as error frame .
  Because decoder to detect CS type it needs four
  valid controls . So , any one of those control
  being error will get deceoded as error frame .

thanks
Sumit

-----Original Message-----
From: Tuan Hoang [mailto:tuanh@xxxxxxxxxxxx]
Sent: Friday, December 07, 2001 11:41 AM
To: stds-802-3-hssg@xxxxxxxx
Cc: Sheila Qiu (E-mail); Sumit Das (E-mail); Chung-Jue Chen (E-mail);
Nong Fan (E-mail)
Subject: Clause 49: S Type Definition and PCS Receive State machine (
Figure 49-13)




In clause 49, the S type definition is :

The vector contains Syn header of 10 and one of the following :
a) A block type filed of 0x33 and four valid control chearacters.
b).....



In a minimum IPG case, there might be two consecutive 64b/66b frames
transmitted by the PCS TX as followed:

  10 0xff Data Data Data Data Data Data Data
  10 0x33 Idle Idle Idle Idle Data Data Data

Due to a bit error, the above frames might be seen at the PCS receiver as:

  10 0xff Data Data Data Data Data Data Data
  10 0x33 Invalid_control Idle Idle Idle Data Data Data

According the the S type definitition, the second frame can not be decoded
as valid frame of "C C C C SOP Data Data Data".  However, the PCS Receive
State machine (Figure 49-13) does not allow a direct trasition of RX_T to
RX_E state.  Then how should the PCS Receiver decode this frame?  Should it
decode the invalid_control byte to ERROR byte and leave the rest of frame
intact? Or should it make the whole frame to be ERROR frame?  It looks like
that the requirment of S type and the state machine are in conflict for this
minimum IPG case.

Tuan