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AW: [802.3ae_Serial] another question on pattertn defined in the current draft:




Hi,
Can somebody help me to understand why the pattern in case of Loop back is
set to 00-FF?
My question is was there a strong reason for this that I do not know. What I
know is that there are some 
ugly effects possible with such pattern when the interface is connected to a
Sonet or other type transport network.
I understand that at the last meeting some work has been done on this loop
back facilities. Now I read in 
50.3.9 Loopback:
............................................................................
...........................the WIS shall transmit a constant pattern
to the PMA sublayer, and shall ignore all data presented to it by the PMA
sublayer. The pattern output to
the PMA transmit path at this time shall consist of a sequence of 8 logic
zero bits and 8 logic one bits, form-ing
the 16-bit word 00-FF hexadecimal. No SONET overhead or fixed stuff shall be
output to the PMA at
this time.


While agreeing that the data incoming to the PMA sublayer should not be 
sent further such constant pattern is likely to generate some ugly
additional 
effects . So maybe this would lead to  undefined and miss leading alarms  
or( or even protection actions) in a possible transport network. This
transport 
network that can either be a plane Sonet transport network, but also a
traditional 
WDM network with Sonet non-intrusive monitoring or transport via an OTN. In
all those 
cases the consequence on such patterns are not defined and the alarms that
will 
be generated are likely to be miss interpreted. For instance it can be 
interpreted that a wrong signal is connected. In case a proper AIS is 
inserted however the transport network will react in the standardized 
way and no alarms (or even protection switches as worst case scenario) 
will be activated (which should not be done when a client equipment is 
in test mode). 
So can somebody help me with the reason for this pattern ( In contrast to a
normal AIS
that would not generate such effects). If there is no particular overriding
reason for this
I would strongly suggest  to take the AIS signal instead.
Regards Juergen Rahn