Fans Test

EX4200 switches have a single fan tray on the rear panel. The fan tray is a hot-removable and hot-insertable field-replaceable unit (FRU): You can remove and replace it without powering off the switch or disrupting switch functions.

The fan tray used in the switch comes with load-sharing redundancy that can tolerate a single fan failure at room temperature (below 113°F/45°C) to still provide sufficient cooling.

Under normal operating conditions, the fans in the fan tray run at less than full speed. If a fan fails or the ambient temperature rises above the threshold 113°F (45°C), the speed of the remaining fans is automatically adjusted to keep the temperature within the acceptable range, 32 °F (0 °C) through 113 °F (45 °C).

The system raises an alarm if the fan fails or if the ambient temperature inside the chassis rises above the acceptable range. If the temperature inside the chassis rises above the threshold temperature, the system shuts down automatically.

This test intercepts the fan failure traps sent by the switch, extracts relevant information related to the failure from the traps, and reports the count of these trap messages to the eG manager. This information enables administrators to detect the fan failures if any, understand the nature of these failures, and accordingly decide on the remedial measures.

Target of the test : A Juniper EX Switch

Agent deploying the test : An external agent

Outputs of the test : One set of results for each type of failure event that occurred on the target Juniper EX Switch.

Configurable parameters for the test
Parameters Description

Test Period

How often should the test be executed


The host for which the test is to be configured.

Source Address

Specify a comma-separated list of IP addresses or address patterns of the hosts from which traps are considered in this test. For example,,192.168.10.*. A leading '*' signifies any number of leading characters, while a trailing '*' signifies any number of trailing characters.

OID Value

By default, this parameter is pre-configured with a comma-separated list of Display name:OID pairs returned by the traps for specific failure events/conditions.

The DisplayName in every pair will appear as descriptors of this test in the monitor interface.

You can, if you so wish, override this default specification by appending more DisplayName:OID pairs to the pre-configured list. This way, you can instruct the test to receive traps for failure conditions that are of interest to you. For example, say you want to capture the traps generated for fan failure on the target Juniper EX Switch. To achieve this, you need to append an entry of the following format: DisplayName:OID-any. Typically, the DisplayName can be any meaningful text string that qualifies the failure condition that is to be captured. Since our example seeks to capture fan failure condition, let us use 'FanFailure' as the appropriate DisplayName. The OID that reports fan failure on Juniper EX Switch is . Therefore, the entry you need to append to the default list will be: FanFailure:. Similarly, you can append more entries. However, make sure that the new entries are also comma-separated.


Specifying True against ShowOID will ensure that the detailed diagnosis of this test shows the OID strings along with their corresponding values. If you enter False, then the values alone will appear in the detailed diagnosis page, and not the OIDs. 


By default, this parameter is set to all, indicating that the eG agent considers all the traps received from the specified sourceaddresses. To make sure that the agent considers only specific traps received from the SourceAddress, then provide a comma-separated list of OIDs in the trapoids text box. A series of OID patterns can also be specified here, so that the test considers only those OIDs that match the specified pattern(s). For instance, *94.2*,*.*, where * indicates leading and/or trailing spaces.

DD Frequency

Refers to the frequency with which detailed diagnosis measures are to be generated for this test. The default is 1:1. This indicates that, by default, detailed measures will be generated every time this test runs, and also every time the test detects a problem. You can modify this frequency, if you so desire. Also, if you intend to disable the detailed diagnosis capability for this test, you can do so by specifying none against DD frequency.

Measurements made by the test
Measurement Description Measurement Unit Interpretation

Failed fans

Indicates the number of events of this type that were triggered during the last measurement period.


The failure events may be generated due to the failure of the fans of the Juniper EX Switch. If the failure events are not rectified within a certain pre-defined timeperiod, the storage system will be shutdown automatically.

Ideally, the value of this measure should be zero. A high value is an indication of performance degradation of the Juniper EX Switch.