This disclosure is related to devices, systems, and techniques for controlling a flow of network traffic between two or more devices. For example, a network device includes a control unit, a forwarding unit including a forwarding manager including a server configured to store a tunnel hierarchy structure, and a packet processor. The packet processor is configured to receive, via an interface card of a set of interface cards, a packet including a packet header. The forwarding manager is configured to parse the packet header in order to identify a service corresponding to the packet, wherein the service is associated with a service color, identify, based on the tunnel hierarchy structure, a set of tunnels, wherein each tunnel of the set of tunnels is associated with a tunnel color, and determine whether at least one tunnel of a set of tunnels associated with the tunnel color is in an online state.