Fine-granularity admission and flow control for rack-level network connectivity

A method for admission and flow control, comprising:

• routing, by a switch, network traffic from each of a plurality of ingress ports to one or more of a plurality of egress ports through a plurality of interfaces including a first interface and a second interface,
• wherein the network traffic has a plurality of classes of service including a first class and a second class,
• wherein each interface of the plurality of interfaces corresponds to a respective ingress port from the plurality of ingress ports and comprises a plurality of class of service queues (CoS-Qs) corresponding to respective classes of service from the plurality of classes of service,
• wherein the plurality of CoS-Qs includes a first COS-Q corresponding to the first class and a second COS-Q corresponding to the second class, and
• wherein routing, by the switch, the network traffic comprises:
• detecting congestion in the first CoS-Q in the first interface;
• and
• blocking network traffic from the first CoS-Q in the first interface to an egress port from the plurality of egress ports, while continuing to (1) route, to the egress port, network traffic from the second COS-Q in the first interface, and (2) route, to the plurality of egress ports including the egress port, network traffic from the first and second CoS-Qs in the second interface.