Description

SNMP Health Monitoring is a useful tool to monitor common attributes such as CPU and memory usage. By default, it monitors the CPU and memory utilization of the first two Routing Engines (REs) in a system. However, a SRX5K Chassis Cluster can host up to four REs, where the third RE is node1's RE 0.

This article is a guide on how to use RMON to emulate some of SNMP Health Monitoring's attributes for node1's RE 0.
 

Symptoms

In a SRX5K Chassis Cluster, a total of four REs maybe installed. These REs are represented in the following order under the jnxOperatingEntry MIB tree:

{primary:node0}
root@srx5k> show snmp mib walk jnxOperatingDescr | match Engine 
jnxOperatingDescr.9.1.0.0 = node0 Routing Engine 0
jnxOperatingDescr.9.2.0.0 = node0 Routing Engine 1
jnxOperatingDescr.9.3.0.0 = node1 Routing Engine 0
jnxOperatingDescr.9.4.0.0 = node1 Routing Engine 1

SNMP Health Monitoring, when configured, will only monitor the first two RE OID relating to Node0:

{primary:node0}
root@srx5k> show snmp health-monitor | match cpu        

 32770 Health Monitor: RE 0 CPU utilization
       jnxOperatingCPU.9.1.0.0                            4 active              

 32771 Health Monitor: RE 1 CPU utilization
       jnxOperatingCPU.9.2.0.0                            4 active
...


Node1's RE 0, which is represented with instance ID of 9.3.0.0, is not covered by SNMP Health Monitoring.
 

Solution

Since the feature is essentially a conveniently packaged set of RMON settings, we can mimic the same behavior by configuring RMON manually for the third RE. We'll focus on RE CPU utilization as an example. To begin, we look at the health-monitor's attributes for node0's RE 0 CPU utilization, which is tracked under jnxOperatingCPU.9.1.0.0:

{primary:node0}
root@srx5k> show snmp health-monitor alarms detail | find operatingcpu    
  Variable name                        jnxOperatingCPU.9.1.0.0
  Variable OID                         1.3.6.1.4.1.2636.3.1.13.1.8.9.1.0.0
  Sample type                          absolute value
  Startup alarm                        rising alarm
  Owner                                Health Monitor: RE 0 CPU utilization     
  Creator                              Health Monitor
  State                                active    
  Sample interval                  300 seconds
  Rising threshold                  90
  Falling threshold                 50
  Rising event index             32768
  Falling event index            32768
    Instance Value: 3
    Instance State: falling threshold
...


{primary:node0}
root@srx5k> show snmp rmon events detail | find 32768 

Event Index 32768:
  Description                         Health Monitor event
  Type                                log and trap
  Last event                          2019-12-05 19:12:47 EST
  Owner                               Health Monitor                            
  Creator                             Health Monitor
  State                               active   


To implement the same monitoring parameters for node1's RE 0 CPU utilization, copy and paste the following set-commands into the config:

set snmp rmon alarm 9300 description "node1: RE 0 CPU utilization"
set snmp rmon alarm 9300 interval 300
set snmp rmon alarm 9300 variable jnxOperatingCPU.9.3.0.0
set snmp rmon alarm 9300 sample-type absolute-value
set snmp rmon alarm 9300 startup-alarm rising-alarm
set snmp rmon alarm 9300 rising-threshold 90
set snmp rmon alarm 9300 falling-threshold 50
set snmp rmon alarm 9300 rising-event-index 9300
set snmp rmon alarm 9300 falling-event-index 9300
set snmp rmon event 9300 type log-and-trap


After committing the config changes, verify the RMON alarms in CLI and observe that they have similar settings as the ones pre-configured by SNMP Health Monitor:

{primary:node0}
root@srx5k> show snmp rmon alarms detail | find operatingcpu 
  Variable name                        jnxOperatingCPU.9.3.0.0
  Variable OID                         1.3.6.1.4.1.2636.3.1.13.1.8.9.3.0.0
  Sample type                          absolute value
  Startup alarm                        rising alarm
  Owner                                monitor: node1: RE 0 CPU utilization     
  Creator                              CLI       
  State                                active    
  Sample interval                  300 seconds
  Rising threshold                  90
  Falling threshold                 50
  Rising event index              9300
  Falling event index             9300
    Instance Value: 70
    Instance State: active
...


{primary:node0}
root@srx5k> show snmp rmon events detail | find 9300 

Event Index 9300:
  Type                                log and trap
  Creator                             CLI       
  State                               active   
...


The same method can be applied to monitor memory utilization by using the OID jnxOperatingBufferCP.9.3.0.0. The remaining variables monitored by the feature do not apply as they are only relevant to the Routing Engine that has primary status for Redundancy-Group 0 (RG-0).
 

Modification History

19-11-2025: Minor, non-technical edit

Related Information

 Understanding Health Monitoring