# Trend (Performance)

The Trend chart shows the historical values measured by all devices and all switches in a fabric. The value represents the aggregated metric on all data traffic types: internal, external, send, and transmit (received). See General Summary (Performance) for information about the different traffic types.

The second axis at the right side of the chart represents the number of no response ports within the fabric. If an issue happens when PA collects data, a mark at the top of the trend chart indicates that the data may be inaccurate. Move your mouse over the mark to display detailed information about the issue type and number of no response ports.