In physical in-path deployments, the SteelHead LAN and WAN ports that traffic flows through are internally connected by circuitry that can take special action in the event of a disk failure, a software crash, a runaway software process, or even loss of power to the SteelHead.

All SteelHead models and in-path network interface cards support fail-to-wire mode, where, in the event of a failure or loss of power, the LAN and WAN ports become internally connected as if they were the ends of a crossover cable, thereby providing uninterrupted transmission of data over the WAN. The default failure mode is fail-to-wire mode.

Certain in-path network interface cards also support a fail-to-block mode, where in the event of a failure or loss of power, the SteelHead LAN and WAN interfaces completely lose link status. When fail-to-block is enabled, a failed SteelHead blocks traffic along its path, forcing traffic to be rerouted onto other paths (where the remaining SteelHeads are deployed).

For information about fail-to-block mode, see Fail-to-Block Mode. For information about SteelHead LAN and WAN ports and physical in-path deployments, see The Logical In-Path Interface. For information about physical in-path deployments, see Physical In-Path Deployments.