Systems of redundant in-line network switch appliances are described. In an embodiment, a system includes a primary network switch appliance and a secondary network switch appliance communicatively coupled in-line between nodes on a computer network. A tool, for example for network monitoring, is communicatively coupled to the primary network switch appliance. In use, when the primary network switch appliance is in a first state, a bypass switch of the primary network switch appliance is configured to complete a communication path between the tool and a node on the computer network via a switching fabric of the primary network switch appliance. When the primary network switch appliance is in a second state, the bypass switch is configured to complete a communication path between the tool and the node on the computer network via the secondary network switch appliance, bypassing the switching fabric of the primary network switch appliance.