Junos OS

Can I use SNMP to determine the health of the processes running on the Routing Engine?

By Elevate posted 02-01-2016 09:46

  

Question

Can I use SNMP to determine the health of the processes running on the Routing Engine?

Answer

Yes, you can use SNMP to determine the health of the Routing Engine processes by configuring the health monitoring feature.

 

Junos OS supports remote monitoring (RMON) as defined in RFC 2819, Remote Network Monitoring Management Information Base. However, remote monitoring version 2 (RMON 2) is not supported, and IPv6 is not supported by the Ping MIB for remote operations.

 

On Juniper Networks devices, RMON alarms and events provide much of the infrastructure needed to reduce the polling overhead from the NMS. However, you must set up the NMS to configure specific MIB objects into RMON alarms. This often requires device-specific expertise and customizing the monitoring application. Additionally, some MIB object instances that need monitoring are set only at initialization, or they change at runtime and cannot be configured in advance.

 

To address these issues, the health monitor extends the RMON alarm infrastructure to provide predefined monitoring for a selected set of object instances, such as file system usage, CPU usage, and memory usage, and includes support for unknown or dynamic object instances, such as Junos OS software processes.

 

To display the health monitoring configuration, use the show snmp health-monitor command:

 

user@host> show snmp health-monitor
interval 300
rising-threshold 90;
failing-threshold 80;

 

When you configure the health monitor, monitoring information for certain object instances is available, as shown in the following table.

Object

Description

jnxHrStoragePercentUsed.1

 

Monitors the following file system on the router or switch: /dev/ad0s1a:

This is the root file system mounted on /.

jnxHrStoragePercentUsed.2

 

Monitors the following file system on the router or switch: /dev/ad0s1e:

This is the configuration file system mounted on /config.

jnxOperatingCPU (RE0)

jnxOperatingCPU (RE1)

Monitor CPU usage for Routing Engines RE0 and RE1. The index values assigned to the Routing Engines depend on whether the Chassis MIB uses a zero-based or a ones-based indexing scheme. Because the indexing scheme is configurable, the correct index is determined whenever the router is initialized and when there is a configuration change. If the router or switch has only one Routing Engine, the alarm entry monitoring RE1 is removed after five failed attempts to obtain the CPU value.

jnxOperatingBuffer (RE0)

jnxOperatingBuffer (RE1)

Monitor the amount of memory available on Routing Engines RE0 and RE1. Because the indexing of this object is identical to that used for jnxOperatingCPU, index values are adjusted depending on the indexing scheme used in the Chassis MIB. As with jnxOperatingCPU, the alarm entry monitoring RE1 is removed if the router or switch has only one Routing Engine.

sysApplElmtRunCPU

 

Monitors the CPU usage for each Junos OS software process. Multiple instances of the same process are monitored and indexed separately.

sysApplElmtRunMemory

 

Monitors the memory usage for each Junos OS software process. Multiple instances of the same process are monitored and indexed separately.

 

The system log entries generated for any health monitor events, such as thresholds crossed and errors, have a corresponding HEALTHMONITOR tag rather than a generic SNMPD_RMON_EVENTLOG tag. However, the health monitor sends generic RMON risingThreshold and fallingThreshold traps.

 

For a list of supported standard and enterprise-specific MIBs, click SNMP MIBs and Traps Reference


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