In the midst of increasing networking device deployments, the need to have a well defined manageability and monitoring system has been existent since some time now. To cater to this need of a network management system, the Simple Network Management Protocol was incorporated and defined by IETF.
SNMP is based on a model consisting of an SNMP manager, SNMP agent, a database of management information and managed SNMP devices. An SNMP agent exposes management data of the managed devices as variables to the SNMP manager.
Now, let’s consider the NetScaler ADC. The SNMP agent on NetScaler ADC generates asynchronous notification Events called traps. NetScaler generates corresponding trap message whenever some events occur.
The NetScaler appliance provides a set of condition entities called SNMP alarms. When any of the alarm conditions are met, the NetScaler generates SNMP trap messages that are sent to the configured SNMP manager.
Command Center is a well composed Manageability and Monitoring Solution offered by Citrix. It can manage all the Citrix networking appliances like NetScaler ADC, Repeater devices, AGEE, Cloud Bridge, and SDX.
When Command Center (CC) is configured as the SNMP manager, the managed device like NetScaler ADC, routes the traps generated, to the Command Center Server. Every single trap routed to CC is recorded as an individual Event in Command Center server. CC stores these events for six months and displays only the latest 10,000 events.
Whenever a trap is received at the Command Center, along with the Event, an Alarm is also generated. To understand this better, let’s consider an example. Let’s say, Command Center gets a trap for an Entity Down category for vip123 virtual server on 10.102.60.5 NetScaler device.
An Event and an Alarm will be generated for vip123 virtual server with Entity Down category under 10.102.60.5 device. Next time vip123, Entity Down trap is received by the Command Center from 10.102.60.5 device, an individual Event will be generated. But under Alarms, only the previously generated alarm will get updated with the latest detail of vip123. At the same time, this alarm will maintain the previously received events under vip123 as history.
This way, you will always find more Events for a specific device than Alarms. Both Alarms and Events are associated with a default severity level.
Now, this event/alarm system boils down to what these Alarms notify to the Command Center’s administrator. Based on the traps default severity levels, the administrator will be notified if it’s a critical, major, minor, warning, info or clear Alarm.
If an Entity down alarm is generated, it gets cleared only when corresponding Entity up trap is received at the CC server. If an Entity down trap is not generated for another 24 hours, this clear alarm will be removed from the system.
For all these alarms, based on your specific criterion you can also create an email notification system by creating an Alarm trigger.
With Events, Alarms and Alarm triggers, the Command Center presents a robust manageability and monitoring solution that gives the right notification at the right time to the right person!