TECHNICAL FIELD

The subject matter of this disclosure relates in general to the field of computer networking, and more particularly to efficiently discovering and communicating with silent hosts in software-defined networks.

BACKGROUND

The enterprise network landscape is continuously evolving. There is a greater demand for mobile and Internet of Things (IoT) device traffic, Software as a Service (SaaS) applications, and cloud adoption. In recent years, software-defined enterprise network solutions have been developed to address the needs of enterprise networks. Software-defined enterprise networking is part of a broader technology of software-defined networking (SDN) that includes both software-defined wide area networks (SDWAN) and software-defined local area networks (SDLAN). SDN is a centralized approach to network management which can abstract away the underlying network infrastructure from its applications. This de-coupling of data plane forwarding and control plane can allow a network operator to centralize the intelligence of the network and provide for more network automation, operations simplification, and centralized provisioning, monitoring, and troubleshooting.

In some enterprise networks, there may be some endpoints which remain silent and difficult to discover. For example, badge readers, building management systems, some IoT devices, printers, etc., may be in a sleep mode or silent without actively sending traffic on the network fabric until they are woken up. In some cases the silent hosts may connect to the enterprise fabric through local area networks (LANs) or other layer 2 networks, where they may traditionally be implemented as wake-on-LAN devices.

For example, within the LAN, the silent hosts may be woken up by directing traffic to the silent host intended to wake up the silent host and cause the silent host to respond. However, some silent hosts, by virtue of remaining silent may not have registered their source address, which makes directing traffic to the silent hosts a challenge. Conventionally, this challenge may be addressed by broadcasting packets intended for the silent host across the entire network, with the intent that the traffic will reach the silent host wherever the silent host may be located. Broadcasting packets across the entire network is also referred to as flooding. When the silent host receives the intended traffic based on the flooding, the silent host may wake up and respond as appropriate.

However, flooding the network in this manner is not a scalable or feasible approach to reach a silent host over a software defined network. For example, when a source device wishes to reach the silent host across an SDN, the source device may direct traffic intended for the silent host to a fabric device (e.g., an edge/border router) that the source device is connected to. The fabric device may obtain a map for routing traffic from a control plane implemented in the SDN traffic based on the intended destination for the traffic. In the case of a silent host, a registration may not be available for the silent host's location, and so the control plane will not be capable of supplying the route for directing traffic to a silent host. The of devices directly and indirectly connected to the enterprise fabric on an SDN are potentially of orders of magnitude higher than the number of devices which may be connected on a traditional layer 2 LAN. Thus, attempting to detect a silent host using the same approach as described within a LAN (e.g., blindly flooding the entire enterprise fabric) is not a feasible option.

