From Tanenbaum's Computer Networks:
The general name for a machine that makes a connection between two or more networks and provides the necessary translation, both in terms of hardware and software, is a gateway. Gateways are distinguished by the layer at which they operate in the protocol hierarchy. We will have much more to say about layers and protocol hierarchies starting in the next section, but for now imagine that higher layers are more tied to applications, such as the Web, and lower layers are more tied to transmission links, such as Ethernet.
Since the benefit of forming an internet is to connect computers across net- works, we do not want to use too low-level a gateway or we will be unable to make connections between different kinds of networks. We do not want to use too high-level a gateway either, or the connection will only work for particular ap- plications. The level in the middle that is ‘‘just right’’ is often called the network layer, and a router is a gateway that switches packets at the network layer.
Is "makes a connection between two or more networks" exactly what a router does?
Is "provides the necessary translation" exactly what a NAT does? What is the "translation"?
Does the quote mean a gateway has to be a router and a NAT?
If "translation" means NAT, a router can't be a gateway, because it doesn't do what a NAT does, correct? Or does "translation" mean something strictly in the network layer?