This counter records the number of Ethernet frames between 128 and 255 octets received on this port during the archived historical interval. As part of the port's historical frame-size distribution, it helps the admin see how the traffic-size mix looked during a specific past period, useful when investigating a change in application behavior. For example, an admin noticing today's traffic mix looks unusually small-packet-heavy would compare against cmEthernetTrafficPortHistoryESP128 from a prior baseline period to see if this represents a real shift.