L4S is an enhanced version of ECN (Explicit Congestion Notification). It spans layer 3 and 4 in the OSI model. ECN works by having a field in the IP header part of the packet that says if the packet experienced congestion on its way to the destination. A ECN-enabled router along the way changes the packet in transit, marking it as congested instead of dropping it. L4S is an advancement upon that, using a bigger field and special handling in routers, which allows for finer grained control over the congestion notification and more advanced algorithms to improve latency.
What Is L4S?
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Re: What Is L4S?
#12Earlier quoted context omitted.
Two things: 1. This is Hacker News, not Facebook. 2. It's possible to answer the question within the first or second paragraph before going on a rant about the surrounding context, regardless the intended audience. Putting forth the entire context first and drowning the reason for going on that rant over halfway down the article is plainly bad writing.
So maybe it shouldn't have been submitted to HN because "Hackers" aren't the intended audience. In which case, downvote and move on with your day.
HN has no doenvote on posts.
Re: What Is L4S?
#13So L4S has to do with your device only? I'm missing something because the ACK of a packet may be enough to indicate congestion.
Your device takes action, but the network tags packets that get delayed and sends that information to the sender, which requires network support.