Subject: [CCAMP] TS granularity & Auto negotiation in OTN

From: [email-masked]
Date: Mon, 4 Apr 2011 15:46:39 -0400

All,

At the ccamp meeting last week I stated the auto negotiation is described 
in G.709.  Unfortunately my memory failed me and I miss spoke.  Having had 
time to check I found that this process is described in clause 14.3.10.1 
of G.798 that describes the adaptation function that supports 1.25G TS 
granularity briefly: 

"The ODUkP/ODUj-21_A_So and _Sk functions start up with PT=21.  If this 
function is connected with an ODUkP/ODUi[j]_A_So and _Sk function, then 
the ODUkP/ODUj-21_A_Sk function will receive an OPUk with PT=20. This 
results in an automatic change of the PT type from PT=21 to PT=20." 

Translation:  Equipment with 1.25GTS granularity starts up in that mode 
and sets PT = 21.  If it receives a PT = 20 (2.5GTS) then it falls back to 
PT=20 operation.   When the link is first turned on (i.e. before any 
"live" traffic or lower order connections are established) a High Order 
ODUk signal with an unequipped signal is sent on the link.  This allows 
the PT (20/21) exchange to take place as soon as the link becomes active.

Hope this clarifies the point.

Key point is that the configuration of the TS granularity is completed 
before the link is made visible to the control plane.

Regards,

Malcolm