OpManager uses monitoring protocols to continuously monitor the uptime and availability of your network devices. You can choose between the three primary availability monitoring protocols - ICMP, TCP and SNMP based on your business needs and the size of for your network. OpManager displays the availability (uptime), packet loss and response time of any device in your network at any given time. Given below is a brief explanation on which monitoring protocol to choose based on the nature of your network.
This protocol is suited best for environments that are ICMP (ping) enabled. ICMP is the default protocol that is chosen by OpManager during device discovery. OpManager sends ping packets to the destination (monitored) device and the device availability, packet loss and response time is calculated based on the ping response pattern received from the monitored device. This ping response pattern varies for different operating systems.
OpManager recommends ICMP protocols for large networks and ICMP (ping) enabled environments. The polling mechanism is comparatively faster than other protocols and this helps you discover devices in your networks that bring in considerable amount of load. ICMP is the default configuration with which the devices are discovered irrespective of the nature of your environment. If your environment doesn't support ICMP, you can change the availability monitoring protocol as TCP or SNMP for devices in bulk post discovery. Unlike other protocols, ICMP does not require any additional configurations (selective ports to be opened in your firewall) to be carried out. The default ping packet size is 1 for Windows and 2 Linux operating systems.
Native Ping: In case the ICMP protocol is restricted in a network, OpManager enables "native ping" for an uninterrupted availability monitoring. Upon every restart, if OpManager identifies that the ICMP is enabled, the native ping is automatically disabled and availability monitoring is continued using ICMP. Alternatively, users can also configure OpManager to use TCP and SNMP for availability monitoring if ICMP is disabled in their environment.
Here, the availability of the configured device is calculated based on the successful socket connection between the OpManager server and the TCP port of the monitored device.
TCP based availability monitoring is most suitable for ping disabled environments or networks that solely prefer TCP port based monitoring for security reasons. OpManager recommends using this protocol for TCP enabled environments that does not attract abundant traffic, i.e., medium scaled networks. OpManager discovers devices using ICMP by default, but can be changed later from the Inventory or individual snapshot pages.
TCP configured port should be allowed by the antivirus or your firewall. The specified port can be any available port between the industry specified range of 0 and 65,535.
SNMP based availability monitoring can only be configured and used if all the device are SNMP implemented. This requires SNMP credentials to be associated with all the monitored devices.
OpManager supports SNMP v1,v2 and v3 credentials. An SNMP ping request is sent to the destination device and the availability monitoring is calculated based on the successful SNMP response from the device. If the SNMP credentials expire, the associated device will be notified as unreachable and marked as Down. The data loss in SNMP based availability monitoring is close to zero and is recommended for medium scaled networks.
Please check the below pages to know more about availability monitoring in OpManager:
Availability monitoring in OpManager
Device availability states and severity
Scalability and hardware recommendations