This counts Errored Blocks on this SONET/SDH port: the number of error-detected blocks (at whatever block granularity applies to this signal's rate) recorded during the bin, per the MIB's description. EB is the block-based error tally that feeds the G.826-style performance parameters for this port -- because it counts blocks rather than seconds, it can distinguish a bin with a few, heavily-corrupted seconds from one with light errors smeared across many seconds, which plain ES on the same bin cannot; because this bin is a closed, archived 24-hour interval, admins typically read it the next day to judge whether the previous day as a whole met SLA rather than to catch a fault as it happens. An EB count of 44 for this bin, spread across relatively few ES for the same interval, would suggest a small number of seconds carried a disproportionate share of the errors on this port.