A slice monitor (A-CNS) for monitoring at least one network slice in a communication network that has a control plane, CP, and a data plane, DP, wherein the CP and DP are separated from each other, each network slice being a collection of inter-connected network functions, NFs, in the CP and the DP, which defines respective CP and DP slices, the slice monitor (A-CNS) comprising: at least one database adapted to store multiple probes, store a collection of probe selection profiles specifying a cost in terms of resources for instantiating each of the multiple probes, store a set of network function, NF, or slice key performance indicators, KPIs, mapped to at least one probe that is actually able to measure the NF or slice KPIs amongst the multiple probes; and at least one engine adapted, as a first operation, to select at least one amongst the at least one probe being mapped to the set of NF or slice KPIs based on multiple profiles selected by different actors from the stored collection of probe selection profiles, and adapted, as a second operation, to instantiate the at least one selected probe based on information from the at least one database, information received from the different actors, and the multiple profiles selected by the different actors, to monitor each CP and DP slice; wherein the at least one database is adapted to store multiple alarms for each NF KPI or each slice KPI associated to a service-level agreement, SLA, each alarm corresponding to a violation of the SLA; characterized in that : the slice monitor (A-CNS) is adapted to transmit over a third interface (I-AS) a slice-oriented request towards a single-slice monitoring device (A-CNS-S) adapted to monitor an individual slice amongst the at least one network slice; and wherein the slice monitor (A-CNS) is adapted to receive over the third interface (LAS), from the single-slice monitoring device (A-CNS-S) and in response to the violation of the SLA detected by an alarm detector of the single-slice monitoring device (A-CNS-S), a request for a reconfiguration of the individual slice through a reconfiguration engine inside the slice monitor (A-CNS). at least one database adapted to store multiple probes, store a collection of probe selection profiles specifying a cost in terms of resources for instantiating each of the multiple probes, store a set of network function, NF, or slice key performance indicators, KPIs, mapped to at least one probe that is actually able to measure the NF or slice KPIs amongst the multiple probes; and at least one engine adapted, as a first operation, to select at least one amongst the at least one probe being mapped to the set of NF or slice KPIs based on multiple profiles selected by different actors from the stored collection of probe selection profiles, and adapted, as a second operation, to instantiate the at least one selected probe based on information from the at least one database, information received from the different actors, and the multiple profiles selected by the different actors, to monitor each CP and DP slice; wherein the at least one database is adapted to store multiple alarms for each NF KPI or each slice KPI associated to a service-level agreement, SLA, each alarm corresponding to a violation of the SLA; characterized in that : the slice monitor (A-CNS) is adapted to transmit over a third interface (I-AS) a slice-oriented request towards a single-slice monitoring device (A-CNS-S) adapted to monitor an individual slice amongst the at least one network slice; and wherein the slice monitor (A-CNS) is adapted to receive over the third interface (LAS), from the single-slice monitoring device (A-CNS-S) and in response to the violation of the SLA detected by an alarm detector of the single-slice monitoring device (A-CNS-S), a request for a reconfiguration of the individual slice through a reconfiguration engine inside the slice monitor (A-CNS). <EOS>