Understanding Redundancy of QFX3008-I Interconnect Device Components and Functionality


The QFX3008-I Interconnect device is a fully redundant system. A redundant QFX3008-I Interconnect device configuration is designed so that no single point of failure can cause the entire device to fail.

The following hardware components provide redundancy for a QFX3008-I Interconnect device:

  • Control Boards—A QFX3008-I Interconnect device has two Control Boards. One Control Board functions as the master, and the other functions as the backup. If the master Control Board fails or is removed, the backup Control Board takes over as the master Control Board. In a QFX3000 QFabric system deployment with multiple QFX3008-I Interconnect devices, traffic halts on the QFX3008-I Interconnect device with a failed Control Board. It resumes once the backup Control Board takes over as the master Control Board. Traffic on other QFX3008-I Interconnect devices continues to be switched normally.

  • Rear cards—The switch fabric circuitry in a QFX3008-I Interconnect device is distributed across eight rear cards. All eight rear cards must be installed in a QFX3008-I Interconnect Device.

    All rear fabric cards are fully connected to all installed 16-port QSFP+ front cards. When the device is operational, all eight rear cards are simultaneously active. If a single rear fabric card fails, the input/output traffic for that card is load-balanced among the remaining rear fabric cards to provide graceful degradation in midplane performance. The impact of a rear fabric card failure on the performance of a QFX3008-I Interconnect device varies based on the traffic mix flowing through the QFX3008-I Interconnect Device.

  • Cooling system—The cooling system in a QFX3008-I Interconnect device consists of ten fan trays. There are eight side fan trays, a front fan tray, and a rear fan tray. Each fan tray has multiple fans. Two fan controllers control the fan trays; each fan controller controls a different set of fan trays. If one fan controller fails, the second fan controller keeps the remaining fan trays working. This allows the device to continue to operate normally.

    Additionally, each fan tray continues to operate indefinitely and provide sufficient cooling even when a fan on the fan tray fails, provided the room temperature is within the operating range. See Cooling System and Airflow in a QFX3008-I Interconnect Device.

  • Power supplies and wiring trays—There are six power supplies and two wiring trays in a QFX3008-I Interconnect device. Each wiring tray provides input power to three power supplies. Each power supply connects to the midplane of the chassis, which distributes the output power produced by the power supplies to different chassis components. (See Midplane in a QFX3008-I Interconnect Device.) Each power supply provides power to a subset of components on the chassis. Together, one wiring tray and set of three power supplies can provide power to the entire system indefinitely. If one power supply fails or is removed, a power supply from the second set of power supplies that powers the same components continues to provide power to those components without interruption. The redundant wiring trays provide 1+1 power feed redundancy for the chassis. The two sets of three redundant power supplies provide 2N system power distribution redundancy for the chassis. See AC Power Supply in a QFX3008-I Interconnect Device and Wiring Tray in a QFX3008-I Interconnect Device.