In a topology that includes a client, OTD and Oracle WebLogic Server (WLS), OTD receives external requests at the configured HTTP listener port. OTD then opens up another connection while communicating and proxying the request to the WLS/origin server.
As part of this connection, OTD leverages ephemeral ports so that WLS/origin server can send data back to OTD. An ephemeral port is a short-lived transport protocol port for Internet Protocol (IP) communications allocated automatically from a predefined range by the IP software. In Linux, you can limit or restrict these ephemeral ports.
Note:
OTD relies on having sufficient ephemeral ports available so that it can have sufficient pool of connections established with WLS/origin server. Not having enough ephemeral ports will cause delays processing the requests.