Question: How the BBR-v2 "degree of aggregation" compares to SCE explicit signal?
Morton's presentation QA an L4s slide of RFC6660 -> RFC5559 is shown with some problems with ECT0/ECT1 marking, BUT those RFCs are defining something called "Pre-Congestion Notification":
" The objective of Pre-Congestion Notification (PCN) is to protect the quality of service (QoS) of inelastic flows within a Diffserv domain in a simple, scalable, and robust fashion. Two mechanisms are used:
admission control, to decide whether to admit or block a new flow request, and (in abnormal circumstances) flow termination, to decide whether to terminate
some of the existing flows. To achieve this, the overall rate of PCN-traffic is metered on every link in the
domain, and PCN packets are appropriately marked when certain configured rates are exceeded. These configured rates are below the
rate of the link, thus providing notification to boundary nodes about overloads before any congestion occurs. The level of marking allows boundary nodes
to make decisions about whether to admit or terminate."
Even if it is important to manage new flows disturbing QoS in the same Diffserv. I view it as low priority than fixing ECN for the "network" with fine-grained info like SCE does. Where and how a diffserv addmission control would be better suited ?
Then the question is where this PCN is actually deployed ?
ps. There are many proposals for ECT(1), maybe a ECN-SANE sub objective would be to document and call out every candidate for a Battle Royale!!!
Relevant RFCs: 6040, 5696, 8311