This sets the peak cell rate for rate queue 1 on this port, the second of the four high-priority queues (0-3). Running a second high-priority queue alongside queue 0 lets this port separate two different latency-sensitive traffic classes, for example voice and signaling, each with its own independently tunable ceiling. An admin dedicating queue 0 to voice and queue 1 to signaling might set pportPeakCellRate1 much lower, say 200 cells per second, since signaling traffic needs far less bandwidth than voice.