The main diffrences between the SNC/I and SNC/N

dear All,
i am studying the SDH technology , i try to understand the main diffrences between the SNC/I and SNC/N , so please any one can provide me by the main diffrences between them ?

sncp in sdh

to find the detailed of this points and diffrences please refer to the ITU-T G.841

sdh sncp

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Re:SNCP I and SNCP N

• SNCP (I) Inherent monitoring
• Path layer connections may be indirectly monitored by using the inherently available data from the multiplex section or higher order path server layers and computing the approximate state of the client path connection from the available data. For example for a higher-order path, impairments detected at the multiplex section adaptation such as AU AIS and AU LOP (Loss of Pointer) are an indication of impairments in underlying server layer networks that affect the client layer connection that is being monitored.
• SNCP(N) Non-intrusive monitoring
• Connections may be directly monitored by the relevant overhead information in regenerator section, multiplex section, higher-order path or lower-order path and then computing the approximate state of the connection from the difference between the monitored states at each end of the connection