This read-write integer sets the interval, in seconds, at which the backup router polls the main router's health, specified as a multiple of ipRedundancyTimeout and defaulting to 3. An admin tunes this alongside the timeout value to balance how quickly a failure is detected against how much polling overhead the redundancy mechanism generates. For example, an admin wanting faster failure detection might reduce ipRedundancyPollingInterval so the backup checks the main router's status more frequently before the timeout elapses.