Network devices provide an important role in receiving and forwarding data packets on a network. Depending upon their role in the network, when in a connected state, devices may be operative to provide a network support function by receiving and forwarding data packets intended for other devices on the network.
In the event of a device failure, the network support function will no longer be operative. Depending upon the network topology employed, failure of a network device may disrupt network traffic for other still functioning devices on the network.
To overcome this limitation, network devices may be provided with a passive bypass mechanism that acts to transition from the connected state to a bypass state by physically disconnecting a failed network device from the network, and physically engaging a bypass circuit to allow network traffic to travel past the failed network device through the network.
Typically, these passive bypass mechanisms are operative to disconnect the failed network device when at least one of one or more pre-determined fault conditions affects operation of the device, such as a power failure to the device, or a fault in the device processing operations allows a bypass watchdog timer within the device to time out.
Depending upon the fault condition, it may be not be possible to re-connect the device without at least physically depowering and subsequently powering the device to initiate a system reboot. If the initial fault condition is attributable to something other than a simple loss of power to the device, it may result that the fault condition returns and the device continually triggers the bypass when the reboot is initiated. In such cases, the ability to troubleshoot the fault condition may be compromised as the device is physically disconnected from the network.
In some circumstances a particular fault or may render it expedient to enforce a bypass state on the network device, though the operational conditions of the network device do not meet the pre-determined fault conditions. Since the passive bypass mechanism only enables a bypass when the pre-determined fault condition affects operation of the device, it will not be possible to enforce the bypass state and the network device will remain physically connected to the network.
In applications where a network device may be physically difficult to reach, or is located in a physically hazardous or distant location, it would be particularly useful to be able to choose whether to engage or disengage a bypass state.