A method and system is provided to enable quality of service across a
backplane switch. An egress queue manager on one blade communicates with
an egress queue manager on another blade where each blade is connected
via a backplane switch. When a blade becomes congested, egress queues
mapped to a destination on the congested blade also become congested. The
egress queue managers determine when to reduce or resume the packet
sending rates of egress queues mapped to destinations on congested blades
using a messaging scheme. Each egress queue manager maintains
notifications of the status of egress queue congestion on its own and
other blades. Normal rates of dequeuing packets are resumed only when the
related congestion on all of the blades has subsided.