This read-only gauge reports the current length, in cells, of the ingress queue for this channel. An admin monitors queue depth as a direct, real-time indicator of how congested this specific virtual channel is at the switch, which helps correlate discard counters with actual buffer buildup. For example, if this ingress queue depth is consistently near its maximum while discard counters are also climbing, the admin has direct confirmation that this channel is genuinely congestion-bound rather than experiencing discards for some other reason.