This read-only Counter32 is a running tally of the total volume of traffic received, in bytes on this individual port since the counter was last reset (it wraps back to zero on overflow, standard SNMP counter behavior). An admin polls rptrPortPktStatsBytes periodically to estimate average frame size and overall utilization when compared against the matching packet counter. For example, comparing rptrPortPktStatsBytes against the same repeater's error/collision counters gives a quick sense of whether this port's traffic level is healthy or already causing contention.