> On 15 Mar, 2019, at 8:36 pm, Mikael Abrahamsson <[email protected]> wrote: > > Having a "lower-than-best-effort" diffserve codepoint might work, because it > means worse treatment, not preferential treatment. > > The problem with having DSCP CPs that indicate preferential treatment is > typically a ddos magnet.
This is true, and also why I feel that just 2 bits should be sufficient for Diffserv (rather than 6). They are sufficient to express four different optimisation targets: 0: Maximum Throughput (aka Best Effort) 1: Minimum Cost (aka Least Effort) 2: Minimum Latency (aka Maximum Responsiveness) 3: Minimum Loss (aka Maximum Reliability) It is legitimate for traffic to request any of these four optimisations, with the explicit tradeoff of *not* necessarily getting optimisation in the other three dimensions. The old TOS spec erred in specifying 4 non-exclusive bits to express this, in addition to 3 bits for a telegram-office style "priority level" (which was very much ripe for abuse if not strictly admission-controlled). TOS was rightly considered a mess, but was replaced with Diffserv which was far too loose a spec to be useful in practice. But that's a separate topic from ECN per se. - Jonathan Morton _______________________________________________ Bloat mailing list [email protected] https://lists.bufferbloat.net/listinfo/bloat
