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RE: Break Link and Remote Fault

Brad, Seto,

Thanks for your suggestions for the LSS update, while I am not yet 
convinced that the argument about LSS in La Jolla is based on the 
sufficient technical understanding, and that we need any update.

Here let me comment to your LSS update suggestion; restricting the 
BL/RF signaling during the pure idle stream alone, not using IPG.  

At 13:29 00/07/17 -0700, Booth, Bradley wrote:
> A couple of options as I see it are the following:
> *	remove OAM&P and move the BL and RF signaling into the idle stream
> *	alter the LSS proposal to only use the idle stream for all signaling

At 15:30 00/07/17 -0700, Seto, Koichiro wrote:
> What I meant by 'not using IPG' was 'not mandating to send LSS signal 
> once in some SONET compatible period'.  I have no problem with the idea, 
> but I thought many other did at the plenary.  As Brad wrote, it is 
> common in Ethernet to send BL/LF signal during periods you don't 
> anticipate MAC to send packets.  I thought many should not have a 
> problem with such a method.  

We have proposed the periodic Link Status (BL/RF) reporting 
just because it is believed to be the simplest solution.  
If we would restrict it during the pure IDLE stream alone, 
we should define/implement the excessive requirements for 
reliable Link Status notification.

Assuming that PHY has been detecting Local Sync Down and 
has been sending the Link Status Code with RF_bit_On.   
If the Local Sync is re-established, then the PHY will 
send the Link Status Code with RF_bit_OFF.  If we have to 
restrict the Link Status Code insertion during the pure 
Idle stream alone, we have to define how many times or 
how long we send it with RF_bit_OFF before we stop to send it.  

Another solution might be just stopping to send the Link 
Status Code itself if the Local Sync is re-established.   
However in this case, at the LS code receiving side, we 
have to define/implement the guard time that how many 
periods or how long we need until we recognize not 
receiving the LS code.  The LS code may be discarded 
at the receiver side by a link bit error, so you need at 
least several periods for not receiving LS code before 
you recognize that the RF is de-asserted.  

I think that these alternative approaches are more complicated 
than just sending the LS code (RF/BL) periodically and simply 
rewrite the status register as it is detected at the receiver side; 
please see slide #9 in my La Jolla presentation;
I also have emotional objection to these approaches since 
these remind me the Auto-Negotiation; defining special PHY 
status (no MAC frame) for Layer-1 RF/BL signaling.

In summary, at present I don't see any reason to make things 
more complicated just for avoiding LS code in IPG, considering 
that there seems to be no reason to distinguish the IDLE columns of 
IPG from those in pure IDLE stream as described in my previous note;

Any feedback on this matter would be greatly appreciated.

Best Regards,

Osamu Ishida,ishida@xxxxxxxxxxxxxxxxxxx
NTT Network Innovation Laboratories
TEL:+81-468-59-3263 FAX:+81-468-55-1282