Environment Control Overview

This section contains the following topics:


Arista switches include internal temperature sensors. The number and location of the sensors vary with each switch model. Each sensor is assigned temperature thresholds that denote alert and critical conditions. Temperatures that exceed the threshold trigger the following:

  • Alert Threshold: All fans run at maximum speed and a warning message is logged.
  • Critical Threshold: The component is shut down immediately and its Status LED flashes orange.

In modular systems, cards are shut down when their temperatures exceed the critical threshold. The switch is shut down if the temperature remains above the critical threshold for three minutes.


Arista switches include fan modules that maintain internal components at proper operating temperatures. The number and type of fans vary with switch chassis type:

  • Fixed configuration switches contain hot-swappable independent fans. Fan models with different airflow directions are available. All fans within a switch must have the same airflow direction.
  • Modular switches contain independent fans that circulate air from front-to-rear panel. Power supplies for modular switches also include fans that cool the power supply and supervisors.

The switch operates normally when one fan is not operating. Non-functioning modules should not be removed from the switch unless they are immediately replaced; adequate switch cooling requires the installation of all components, including a non-functional fan.

Two non-operational fans trigger an insufficient fan shutdown condition. Under normal operations, this condition initiates a switch power down procedure.

Fans are accessible from the rear panel.


Arista switches contain power supplies which provide power to internal components.

  • Fixed configuration switches contain two power supplies, providing 1+1 redundancy.
  • Modular switches contain four power supplies, providing a minimum of 2+2 redundancy.

Power supply LED indicators are visible from the rear panel.