On Tue, Jul 11, 2023 at 10:06:36AM -0700, Jakub Kicinski wrote: > Now we're getting into our favorite argument and completely > sidetracking the conversation, aren't we? :) And as usual > our ability to present facts is limited by various NDAs.. Yes, well, maybe I should stop taking the bait everytime you write "proprietary" :) > > We also have the roce support in the switch from all major > > switch vendors. > > By which you mean all major switch vendors should support basic RoCE > requirements. But most vendors will try to put special features into > their switches trying to make the full NIC + switch solution as sticky > as possible. Yep. At the high end open standards based ethernet has also notably "failed" as well. Every switch vendor now offers their own proprietary ecosystem on a whole bunch of different axis. They all present "ethernet" toward the host but the host often needs to work in a special way to really take full advantage of the proprietary fabric behaviors. > Last I checked every generation of HW from even a single vendor came out > with a new congestion control algorithm and add-ons. Probably, but I don't really view this as an IB or roce issue. Back in the day, there was "data center ethernet" which was a standardization effort to try and tame some of these problems. roce was imagined as an important workload over DCE, but the effort was ethernet focused and generic. Sadly DCE and successor standard based congestion mangement approaches did not work, or were "standardized" in a way that had a big hole that needed to be filled with proprietary algorithms. Eventualy the interest in standardization seems to have waned and several of the big network operators seem to be valuing their unique congestion management as a proprietary element. From a vendor perspective this is has turned into an interop train wreck. Sigh. roce is just highly sensitive to loss - which is managed in ethernet through congestion management. This is why you see roce and congestion management so tightly linked, and perhaps in some deployments becomes the motivating reason to look at congestion management. However, TCP under congestion management is also very interesting and is a motivation to deploy congestion management in its own right in some cases. Jason
