[Bloat] [tsvwg] [Ecn-sane] [iccrg] Fwd: [tcpPrague] Implementation and experimentation of TCP Prague/L4S hackaton at IETF104

Greg White g.white at CableLabs.com
Wed Mar 20 16:55:20 EDT 2019

In normal conditions, L4S offers "Maximize Throughput" +  "Minimize Loss" + "Minimize Latency" all at once.  It doesn't require an application to have to make that false choice (hence the name "Low Latency Low Loss Scalable throughput").  

If an application would prefer to "Minimize Cost", then I suppose it could adjust its congestion control to be less aggressive (assuming it is congestion controlled). Also, as you point out the LEPHB could be an option as well.

What section 4.1 in the dualq draft is referring to is a case where the system needs to protect against unresponsive, overloading flows in the low latency queue.   In that case something has to give (you can't ensure low latency & low loss to e.g. a 100 Mbps unresponsive flow arriving at a 50 Mbps bottleneck).


´╗┐On 3/20/19, 2:05 PM, "Bloat on behalf of Jonathan Morton" <bloat-bounces at lists.bufferbloat.net on behalf of chromatix99 at gmail.com> wrote:

    > On 20 Mar, 2019, at 9:39 pm, Gorry Fairhurst <gorry at erg.abdn.ac.uk> wrote:
    > Concerning "Maximize Throughput", if you don't need scalability to very high rates, then is your requirement met by TCP-like semantics, as in TCP with SACK/loss or even better TCP with ABE/ECT(0)?
    My intention with "Maximise Throughput" is to support the bulk-transfer applications that TCP is commonly used for today.  In Diffserv terminology, you may consider it equivalent to "Best Effort".
    As far as I can see, L4S offers "Maximise Throughput" and "Minimise Latency" services, but not the other two.
     - Jonathan Morton
    Bloat mailing list
    Bloat at lists.bufferbloat.net

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