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RE: Clause 48: enable_cdet


I believe the enable_cdet functionality is the same as the required EN_CDET
signal in the pma service interface of 802.3z.  When true, the PMA will
force any serial +comma to align to it's 10 bit output.  I believe that is
the implied functionality of the enable_cdet signal in 802.3ae but it's not
explicitly stated.

In the LOSS_OF_SYNC state, the enable_cdet signal is forcing the PMA to
align to a comma.  Once a valid comma is detected on the 802.3ae service
interface , enable_cdet can be deasserted.  In 802.3z, there is another
required signal called COM_DET that indicates this condition.  There is no
such required interface signal in 802.3ae so it up to the user to figure out
how and where he/she wants to detect this condition and implement the state

The COMMA_DETECT1-3 states are looking for 3 properly aligned commas in the
absence of an asserted enable_cdet signal.  This would indicate a high
likelihood that the alignment that was forced in the LOSS_OF_SYNC state
(with an asserted enable_cdet) was a good one.


> -----Original Message-----
> From:	Rogers, Shawn [SMTP:s-rogers@xxxxxx]
> Sent:	Monday, March 26, 2001 2:10 PM
> To:	'rich.taborek@xxxxxxxxx'
> Cc:	'802.3ae'
> Subject:	Clause 48:  enable_cdet 
> Rich, I'd like some clarification on this before deciding on whether to
> enter a comment on D2.3.  
> In Figure 48.8, 
>    In the LOSS_OF_SYNC state, enable_cdet = true. 
>    Exiting LOSS_OF_SYNC state is dependent on valid signal detect and
> detecting a comma.  
>    In the COMMA_DETECT_1 state, enable_cdet = false. 
>    Exiting COMMA_DETECT_1 to go to COMMA_DETECT_2 is dependent on a valid
> comma.  
> How do you get to COMMA_DETECT_2 when comma detect is turned off?   
> Also, on a more generic note, why turn off comma detect so early in the
> sync state machine? 
> Shawn 
> ___________________________________________ 
> Shawn Rogers,   PMP 
> s-rogers@xxxxxx 
> Serial Gigabit Products Dev. Mgr. 
> Texas Instruments/ 12500 TI Boulevard 
> M/S 8732/ Dallas, Texas 75243 
> Tel: 214-480-2678, Fax: 214 761-6954 Pager: 972-597-1803 
> ___________________________________________