详细内容参考G.808文件的11.2节。
SNCP可以进一步按照导致SF/SD的失效条件的不同而细分为：
1)Inherent: the server layer's trail termination and adaptation functions are used to determinethe SF/SD condition. It supports detection of server layer defect conditions only.
2)Non-intrusive: non-intrusive monitoring functions are deployed to determine the SF/SD
condition.
a) End-to-end: Detection of server layer defect conditions, continuity/connectivity defectconditions in the layer network, and error degradation conditions in the layer network.The end-to-end overhead/OAM is used.
b) Sublayer: Detection of server layer defect conditions, continuity/connectivity defectconditions in the layer network, and error degradation conditions in the layer network.The sublayer overhead/OAM is used.
3) Sublayer: Tandem connection/segment sublayer functions are deployed to determine theSF/SD condition. It supports detection of server layer defect conditions,
continuity/connectivity defect conditions in the layer network, and error degradationconditions in the layer network. The sublayer overhead/OAM is used.