This amendment specifies protocols, procedures and managed objects that support congestion management of long-lived data flows within network domains of limited bandwidth-delay product. This is achieved by enabling bridges to signal congestion to end stations capable of transmission rate limiting to avoid frame loss.

This standard specifies protocols, procedures, and managed objects to support congestion notification. These allow a Virtual Bridged Local Area Network or a portion thereof, with a limited bandwidth-delay product, to transfer long-lived data flows with a significantly reduced chance of frame loss compared to a network without congestion notification. To this end, it aa) Defines a means for VLAN-aware Bridges that support congestion notification to form Congestion Managed Domains within a Virtual Bridged LAN. ab) Defines a means for detecting congested queues in end stations and VLAN-aware Bridges, for signaling such congestion to the end stations sourcing the frames causing the congestion, and for those end stations to control the rate of transmission of those frames.