Dave Taht <dave.t...@gmail.com> writes: > To be deliberately contrarian - (I do try to only pay attention to > this a few days a month) - after also re-reading > https://www.cablelabs.com/technologies/low-latency-docsis and the > associated white papers (yes, 24 hours on a plane can do this to you) > > 1) I've never been able to figure out where the 99 percentile latency > figure so often cited came from. on the upstream which typically runs > well below 20Mbit, a single IW10 burst at 10Mbit is 1.3ms, so I've > generally figured it was either a long term figure, or calculated from > a much higher (100mbit? 1gbit?) downstream rate against some load > that's never been documented. (that I know of, please note that I > don't > read much of the traffic about this stuff) > > 2) There is a lot of valuable looking stuff in the lower level aspects > of the docsis LL standard. I'd noted it when I first read it, but > achieving .9ms baseline a/g latency finally does make it competitive > with fiber with whatever the heck "pgm" is. So far as I knew, the > overlapping grant request and estimator functions documented in the > patent are already present in most cablemodems already, and not really > tied to the ll spec... but that data would be interesting to get out > of the modem itself, somehow. The histogram is made available via a > MIB to the operator. It would be nice if those MIBs were also visible > to the user somehow. > > 3) > > In the docsis-ll white paper and spec it lays out cmts requirements > also. With the cmtses currently exhibiting 500+ms of latency at > 100Mbit loaded, from a mere "solving bufferbloat" perspective - > getting just pie there to work would be *marvelous* - it would be > superior to any of the fiber deployments I know of. dualpi, even if > not configured for l4s ecn support, would be a godsend. The ECO for > cablemodems at least, went out over a year ago. > > some aqm tech becoming common on these head ends would also spur > deployment of aqm (or fq + aqm) tech on fiber also. But I've seen no > info as to what's going into cmtses today. Haven't seen any > announcements... > > I still have no idea what is going to happen on 5G.
I have heard about 5G vendors implementing CoDel on their modems. Maybe what will end up happening is that all the promises of "low-latency networking" on 5G will end up being true simply because the vendors finally fix their bloat? ;) -Toke _______________________________________________ Bloat mailing list Bloat@lists.bufferbloat.net https://lists.bufferbloat.net/listinfo/bloat