Random Flow Control slowing down ports

[rconaway]

Firmware 1.47. I just got a bunch of calls of slow speeds, not the first time, where some device just arbitrarily has high ping times, sometimes in the hundreds of ms, that is connected to the Netonix switch. Power cycling everything doesn't fix it. And it doesn't seem to be a problem when first installed but just randomly seems to pop up. In retrospect, we did not test for this when first connecting devices but I'm going back and auditing everything to confirm the issue.
The latest is an AF24 that has been connected for almost 2 years and a Peplink on the same switch. Other times we have seen this is with Metrolinq radios also. Auditing Mimosa and Ubiquiti Prism radios right now to see if I can duplicate the problem.

[sirhc]

If you running large flat network segments you have to be careful with Flow Control as UBNT and some other wireless manufacturers have bugs in the way they implement flow control in reference to the wireless bridge and ever changing wireless capacity.

Also one needs to make sure that local radio (APs) Pause Frames are not affecting backhaul radios.

If you're not completely fluent in how pause frames affect switches it is best to turn it off.

Our switches are not software switches they are switch cores so the switch core Flow Control is handled in the core which is an IEEE standard so it is implemented to the IEEE specification. We do not write the switch core code we write the UI, CLI, STATs, POR controls, and the UI to turn on and off switch core functions.

[mike99]

If needed, here a fast explanation of how flow control work and how it could affect performance. It's done a littile fast so not perfect but I think it should be understandable.
viewtopic.php?f=17&t=1823#p19239