Understanding Gateways and Gateway Nodes

A Logical Gateway (called a Gateway in the Management Portal user interface) is a JSON object that defines what its registered nodes should look like. This JSON object resides on the management tier. The definition of each gateway lists the deployed endpoints and the policies applied for each. A gateway node is the physical gateway runtime installation. Gateway nodes can be installed on-premises or in the cloud. Installation of gateway nodes on the same server as the management tier is not supported.

Logical gateways and gateway nodes have a one to many relationship: many nodes can register to one logical gateway, but a node can register to only one logical gateway. Each gateway node polls the management service at configurable intervals to retrieve the JSON logical gateway definition it registers to. See Changing the Node Polling Interval. The node is updated to match the definition. The only period where nodes registered to the same logical gateway are out of sync, except if a given node is down, is if one has polled the management service and updated based on an updated definition and another has not yet polled.

Because you deploy APIs to logical gateways, and not to gateway nodes, all nodes registered to a gateway have the same APIs deployed with the same policies applied. API Managers can consider using the Gateway-Based Routing Policy (see Applying Gateway-Based Routing Policies) to route to different backend services based on which gateway the API is deployed to; otherwise, if you need your nodes to have different API deployments or different policy configuration, you must create separate logical gateways for each configuration you need.