I have disabled the broadcast storm control feature in the FE network ethernet switches.  I suspect the feature is dropping CA broadcast traffic when IOCs go offline, as the number of channels is significant for even one host; this will negatively impact the ability of systems to reconnect to channels when the come back up, and just extend the period of time the broadcasts are active.  There was a marked reduction in the level of dropped frames on the FE network when dc0 was changed to collect EPICS data via the OpenMX network, but there are still peaks of dropped traffic (at a reduced rate).