Overlayed Path Segment Forwarding (OPSF) Problem Statement

Various overlays are used in networks including WAN, enterprise campus and others. End to end path are divided into multiple segments some of which are overlay encapsulated to achieve better path selection, lower latency and so on. Traditional end-to-end transport layer is not very responding to microburst and non-congestive packet loss caused by the different characteristics of the path segments. With the potential transport enhancement for the existing or purposely created overlayed path segment, end to end throughput can be improved. This document illustrates the problems in some use cases and tries to inspire more about whether and how to solve them by introducing a reliable, efficient and non-intrusive transport forwarding over the overlayed path segment(s).