Availability Monitoring

There are two practical treatments of term availability in the context of network monitoring, fitting in two questions: "is a host/interface/service available right now?" and "how often a host/interface/service gets unavailable?". A set of indicators answering the first question we denote as current host availability indicators. An answer to the second question requires multiple measurements at different time points and therefore we refer to statistical availability metrics. The two approaches are described below.

Both approaches use ICMP (basically Ping, or, additionally, Traceroute) requests. If your device does not respond to ICMP requests, you would need to find a different way to monitor its availability. Refer to Ping and Traceroute services for details.

Current Availability

The following current availability indicators are supported by AggreGate Network Manager:

•	Host Online/Offline Status is monitored by Ping service, and can be accessed as Ping service monitoring results or using these tools: Device Offline alert, Offline Devices and Device Status Summary queries.

•	Status of network interfaces on the host (tracked via SNMP). Related tools provided by AggreGate Network Manager: Interface Down and Administrative Interface Down alerts, Down Interfaces report/query.

•	Device Response Time is monitored using Ping service (accessed via Ping service monitoring results). Related tools: High Response Time alert, Ping Time and Response Time Top 10 charts, and Response Time queries/reports.

•	Packet Loss Rate is monitored with Ping service (also accessed via Ping service monitoring results). See High Packet Loss Rate alert, Ping Packet Loss and Packet Loss Top 10 charts, and Packet Loss Rate queries/reports.

•	Host Reachability can be monitoried using Traceroute service. The service provides detailed information about network route to the host.

•	Virtual Machine availability can be monitored using VMware Server monitoring tools, namely Virtual Machine State alert.

•	Printer availability can be monitored using Printer monitoring tools: Printer State, Printer Marker, Printer Cover alerts and Printer Information widget.

•

Service Availability can be monitored using Service Offline alert and Services Status table. The Services Status table is accessible via Favourites item and represents availability/operability statuses of all services running on all registered devices. Status of a service is presented with colors: grey if the service is disabled (i.e. not configured for monitoring), green if it is online, and red if it is offline.

Statistical Availability

Availability as a statistical value is the proportion of time a system is in a functioning condition.

Device availability is measured for a specific time interval as percentage: 100 - packetLossRate, where packetLossRate is percentage of failed ping requests. In AggreGate Network Manager the measure of statistical device availability for time intervals is represented by Availability Not 100% report.