Omni-Path congestion control architecture (CCA) makes use of an explicit congestion notification mechanism. The mechanism permits switches to identify potentially congested links and propagate a notification forward to the destination SuperNIC. In response, the destination SuperNIC reflects the response back to the sending SuperNIC, and the sending SuperNIC reduces its packet injection rate.

The amount of sending rate reduction by the SuperNIC and the timing of rate restoration are dynamically determined by the frequency and pattern of congestion notifications received. When congestion notifications are frequent, the SuperNIC implements more aggressive rate reduction; as notifications decrease, the SuperNIC gradually restores its transmission rate to optimize fabric utilization while preventing congestion.