Benny Lyne Amorsen wrote:
TCP looks quite different in 2023 than it did in 1998. It should handle packet reordering quite gracefully;
Maybe and, even if it isn't, TCP may be modified. But that is not my primary point. ECMP, in general, means pathes consist of multiple routers and links. The links have various bandwidth and other traffic may be merged at multi access links or on routers. Then, it is hopeless for the load balancing points to control buffers of the routers in the pathes and delays caused by buffers, which makes per-packet load balancing hopeless. However, as I wrote to Mark Tinka; : If you have multiple parallel links over which many slow : TCP connections are running, which should be your assumption, with "multiple parallel links", which are single hop pathes, it is possible for the load balancing point to control amount of buffer occupancy of the links and delays caused by the buffers almost same, which should eliminate packet reordering within a flow, especially when " many slow TCP connections are running". And, simple round robin should be good enough for most of the cases (no lab testing at all, yet). A little more aggressive approach is to fully share a single buffer by all the parallel links. But as it is not compatible with router architecture today, I did not proposed the approach. Masataka Ohta