An Inventory of Transport-Centric Functions Provided by Middleboxes: An Operator Perspective
address sharing
NAT
firewall
Service Function
transport
service delivery
Internet architecture
TCP QUIC
Path Layer UDP Substrate
This document summarizes an operator's perception of the benefits that may be provided by intermediary devices that execute functions beyond normal IP forwarding. Such intermediary devices are often called "middleboxes". RFC 3234 defines a taxonomy of middleboxes and issues in the Internet. Most of those middleboxes utilize or modify application- layer data. This document primarily focuses on devices that observe and act on information carried in the transport layer, and especially information carried in TCP packets.