Based on the discussion on the list, I removed the restriction to ECN-enabled (all routers) path segments.
This puts us clearly on the "drop-to-mark" use case — ECN marks on the segment will be forwarded, but we also convert drops into marks by marking recovered packets.
This means end-to-end flows will not benefit from fewer congestion events (which would enhance their throughput), but will benefit from quick recovery (which will help reduce latency).
Based on the discussion on the list, I removed the restriction to ECN-enabled (all routers) path segments.
This puts us clearly on the "drop-to-mark" use case — ECN marks on the segment will be forwarded, but we also convert drops into marks by marking recovered packets. This means end-to-end flows will not benefit from fewer congestion events (which would enhance their throughput), but will benefit from quick recovery (which will help reduce latency).