Node Combining Network (NCN) alarms are alarms that occur above the level of the fiber node, between the fiber node and the hub. ServAssure NXT provides NCN alarms for Outages.
If an outage occurs on a fiber node, ServAssure NXT checks for an NCN alarm. The location of a possible NCN Outage propagates up through the network. The highest level at which an outage can occur is at the hub, when 100% of the CMTSs are offline.
This diagram shows the Node Combining Network. Below the Hub are the CMTSs, the Service Groups, the upstream and downstream Segments, and then the Fiber Nodes. Each Service Group manages a collection of upstream and downstream Segments. Each Segment is a group of upstream and downstream channels.
To pinpoint the location of the NCN alarm, ServAssure NXT calculates the percentage of fiber nodes offline below a Segment. If 100% of the fiber nodes are offline, then ServAssure NXT calculates the percentage of Segments offline. If 100% of the Segments are offline, then ServAssure NXT calculates the percentage of Service Groups offline. If a configurable number of Service Groups are offline, then ServAssure NXT calculates the percentage of CMTSs offline. If 100% of CMTSs are offline, then the Outage is at the Hub. If at any level the required percentage of elements are not offline, the source of the outage is located.
Your ServAssure NXT administrator configures the percentage of CMTSs that must be offline to trigger an NCN Outage alarm. At all other levels, 100% must be offline to trigger an NCN outage. The severity of the alarm is based on the number of modems affected.
An NCN alarm clears all other alarms on each affected fiber node.