Background: Know: problems , Recognize:
Why are causality graphs useful ?
Network management is about monitoring, interpreting and handling events. In causality graphs, events are defined as an exceptional condition in the operation of the network. Some problems are directly observable, while others can be observed only indirectly, by observing their symptoms.
Symptoms are defined as events that are observable; for example, degraded application performance is a symptom of the faulty interface problem. Symptoms can not be handled; to make symptoms go away, it needs to handle its root cause problem. Relationships are essential components of correlation, because problems and symptoms propagate from one object to another along relationships.
Rules of causality graph:
A. One problem causes one symptom;
B. Problems can only lead to others;
C. If symptom could lead to other symptom, it can have outgoing edges
But the node in this graph may be neither problems nor symptom.
"Coding-Based Schemes for Fault Identification in Communication Networks" Chi-Chun Lo; Shing-Hong Chen; Bon-Yeh Lin, 1999, IEEE volume 2.
"Advances in Network Management" Jianguo Ding, 2010 pp. 133