Gateway is a network hardware or a network node that act as an interface with another network using different set of communication protocols. It is a network node that connects two different network using different set of communication protocols and thus enables communication by using more than one protocol. Further gateway supports interoperability between different networks. Further ahead, traffic is routed from workstation to outside network through gateway and it works above the network layer such as application layer.
Multilayer switch is a type of switch which functions like a normal switch in the layer 2 of OSI model, i.e., data link layer but it can provide some additional function on the higher layer of the OSI model. The best feature of the multilayer switch is that it can function like switch as well as router at a very fast speed.
Wireless controller is a centralized wireless management device. It is used for controlling the wireless access point automatically. The network administrator can use the wireless controller with lightweight access point protocol (LAPP) for managing the light-weight access point. Wireless controller is also used for interference mitigation, load balancing, radio broadcasting, and fail over.