When do full queues on switches or routers cause packet issues?

Full queues on switches or routers cause packet issues specifically when the host's incoming packet queue is full. In networking, routers and switches use queues to temporarily hold packets before they are processed or forwarded. When the incoming packet queue reaches its capacity, new packets cannot be accepted. This results in dropped packets, which can lead to increased latency, decreased throughput, and ultimately hinder performance.

When the queue is full, it lacks the ability to adequately manage the flow of incoming data, leading to loss of critical information and requiring retransmission or causing endpoints to wait, which adversely affects application performance. Hence, understanding the implications of a full incoming packet queue is crucial for network management and optimization.