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Re: headless chicken


Thanks for your clear definition of Break Link and Remote Fault.

My point has been that we had better specify the two management 
register bits advertised by Link Signaling; RemoteFault of the 
STATUS register bit (Local Sync Up/Down), and BreakLink of the 
CONTROL register bit (Local Isolate or something else).  I believe 
that this two-bit advertising allows us flexible PHY implementation 
yet preserving the strict Ethernet inter-operability.

Also it would be a good idea to define the Link Status bit in the 
status register to indicate 'Duplex Link Up with valid MAC partner'.
I think this status bit shall be implemented with a latching 
function, such that the occurrence of a NotOK condition will 
be remained until it is read via the management interface.

I agree with your definition below except the BL priority.
The LSS Link Status Code reported once ever 125 usec will carry 3-bit 
information even with minimum 4-bit Hamming protection, and hence 
RemoteFault and BreakLink can be advertised simultaneously.
I don't see any requirement to give priority to BreakLink over 
RemoteFault.  Either or both of them causes Link Status NotOK.

Best Regards,

At 18:54 00/06/27 -0700, Rich Taborek wrote:
> However, I urge you to keep the LSS protocol simple and not include any
> implementation specific features. My view of Remote Fault (RF) and Break Link
> (BL) protocol is as follows:
> Remote Fault:
> - LSS signals RF whenever the link, including all lanes, is not synchronized;
> - LSS RF signaling occurs once every 125 usec +/- 14 usec;
> - Received RF is indicated in a management register (TBD).
> Break Link:
> - LSS signals BL upon management initiative;
> - BL has priority over RF;
> - LSS BL signaling occurs once every 125 usec +/- 14 usec;
> - Received BL is indicated in a management registers (TBD).
> Link Status:
> - Set to OK when the link, including all lanes, is synchronized; and,
> - RF or BL is not being received; 
> - Set to FAIL otherwise.

> Osamu ISHIDA wrote:
> > 
> > Local Device #1                           Remote Device #2
> > 
> >    MAC                                               MAC
> >     |   STA #1                         STA #2         |
> >    PHY  Register                       Register      PHY
> >     |    Local State                    #1 State      |
> >     |     Sync Up/Down --(RemoteFault#1)---->         |
> >     |     Isolate      ---(BreakLink#1)----->         |
> >     |    Remote State                   #2 State      |
> >     |             <----(RemoteFault#2)-- Sync Up/Down |
> >     |             <-----(BreakLink#2)--- Isolate      |
> >     |_________________________________________________|

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