> On 20 May, 2016, at 16:41, David Lang <da...@lang.hm> wrote: > > On Fri, 20 May 2016, Jonathan Morton wrote: > >> Normal traffic does not include large numbers of fragmented packets (I would >> expect a mere handful from certain one-shot request-response protocols which >> can produce large responses), so it is better to shunt them to a single >> queue per host-pair. > > I don't agree with this. > > Normal traffic on a well setup network should not include large numbers of > fragmented packets. But I have seen too many networks that fragment almost > everything as a result of there being a hop that goes through one or more > tunneling layers that lower the effective MTU (and no, path mtu discovery > does not always work)
One case of which would be the misconfigured PPPoE link Sebastian mentioned. But I don’t think this is as big a problem as you do. Most latency-sensitive protocols (and critical TCP phases such as handshake and teardown) use sub-MTU sized packets, so are less likely to be fragmented, so will still benefit from flow isolation. And under normal circumstances, most MTU-sized packets are associated with congestion-responsive protocols, which can tolerate being shunted into a single AQM-managed subqueue per host-pair. Flow isolation also still occurs between traffic to different hosts. - Jonathan Morton _______________________________________________ Codel mailing list Codel@lists.bufferbloat.net https://lists.bufferbloat.net/listinfo/codel
