The range delay of each of a plurality of user devices of an HFC is monitored. If the delay of a number of devices shifts by about the same amount and at about the same time, then the number of devices having such a shift is compared to a predetermined threshold. If the number exceeds the threshold, it is assumed that a leg of a fiber ring in the HFC has been severed, and a ring switch is determined to have occurred.Upon this determination, granting of bandwidth requests to a group of user devices is suspended, and a ranging and register process for all devices in the group begins. The group may comprise all user devices affected by the broken fiber ring. Following ranging and registering, granting of bandwidth requests to the affected devices begins according to a normally-provisioned request grant schedule.