Method and apparatus for providing quality of service across a switched backplane between egress and ingress queue managers

A method for enabling quality of service between an ingress queue and an egress queue comprising:

• receiving a congestion message identifying a congested egress queue of a first blade in a router, the first blade coupled to a switched backplane of the router, the congested egress queue enqueueing data packets dequeued from one or more ingress queues of the first blade, wherein the egress queue is to send the packets to a port of the first blade, wherein the one or more ingress queues are to dequeue only packets to be sent to the port;
• and
• in response to receiving the congestion message,
• determining that the port is an outer port of the router, and
• in response to determining that the port is an outer port of the router, reducing a rate of dequeueing data packets from all ingress queues which are to dequeue packets to the outer port.

A method for enabling quality of service between an ingress queue and an egress queue comprising:

• receiving a congestion message identifying a congested egress queue of a first blade in a router, the first blade coupled to a switched backplane of the router, the congested egress queue enqueueing data packets dequeued from one or more ingress queues of the first blade, wherein the congested egress queue is to send the packets to a port of the first blade, wherein the one or more ingress queues are to dequeue only packets to be sent to the port;
• and
• in response to receiving the congestion message,
• determining that the port is a backplane port sending packets to the switched backplane, and
• in response to the determining that the port is a backplane port,
• determining a destination blade associated with the backplane port, and
• reducing a rate of dequeueing data packets from all ingress queues which are to dequeue only packets to be sent to ports on the destination blade.

An apparatus to control congestion, the apparatus comprising:

• a first blade to couple to a switched backplane, the first blade including
• a port,
• one or more ingress queues to dequeue packets, wherein the one or more ingress queues are to dequeue only packets which are to be sent to the port, and
• an egress queue to receive packets dequeued by the one or more ingress queues, the egress queue further to send the received packets to the port;
• a first egress queue manager associated with the first blade, the first egress queue manager to detect that the dequeueing of data packets from the one or more ingress queues is contributing to a congestion of the egress queue, and in response to the detecting, the first egress queue manager further to
• generate a congestion message,
• determine whether the port is a backplane port to send packets to the switched backplane, and
• if the port is determined to be a backplane port,
• reduce a rate of dequeueing packets from an egress queue to a destination blade receiving packets via the backplane port, and
• send another congestion message from the first blade to another blade coupled to the switched backplane, the other congestion message including an identifier of the port, wherein the other blade, based on the identifier of the port in the congestion message from the first blade, reduces a rate of dequeueing packets which are to be sent to the destination blade;
• and
• an ingress queue manager associated with the first blade to receive the congestion message and further to reduce, in response to the congestion message, a rate of dequeueing packets to the congested egress queue.

A system to control congestion, the system comprising:

• a switched backplane;
• a first blade coupled to the switched backplane, the first blade including
• a port,
• an ingress queue which is to dequeue only packets to be sent to the port, the ingress queue having a rate of dequeueing packets, and
• an egress queue having a queue threshold, the egress queue to receive packets dequeued by the ingress queue, the egress queue further to send the received packets to the port;
• an egress queue manager to monitor congestion on the egress queue;
• an ingress queue manager coupled with the egress queue manager to regulate the rate of dequeueing packets from the ingress queue in response to a congestion message;
• and
• a processor to carry out instructions from the egress queue manager to send the congestion message to the ingress queue manager when a depth of the egress queue exceeds the queue threshold and to carry out instructions from the ingress queue manager to reduce the rate of dequeueing packets from the ingress queue until the depth of the egress queue recedes below the queue threshold, the processor further to carry out instructions from the egress queue manager to determine, in response to the depth of the egress queue exceeding the queue threshold, whether the port is a backplane port to send packets to the switched backplane, and, if so, further to
• reduce a rate of dequeueing packets from the egress queue to the port, and
• send another congestion message from the first blade to another blade coupled to the switched backplane, the other congestion message including an identifier of the port, wherein the other blade, based on the identifier of the port in the congestion message from the first blade, reduces a rate of dequeueing packets which are to be sent to a destination blade receiving packets from the port.

An apparatus to communicate queue control information, the apparatus comprising:

• means for detecting that a dequeueing of data packets from one or more ingress queues of a first blade to an egress queue of the first blade is contributing to a congestion of the egress queue, wherein the first blade is coupled to a backplane switch, wherein the egress queue is to send the packets dequeued from the one or more ingress queues to a port of the first blade, and wherein the one or more ingress queues are to dequeue only packets which are to be sent to the port;
• means, responsive to the detecting, for generating a congestion message identifying a queue number of the egress queue, the first blade, and the port;
• means, responsive to the detecting, for determining whether the port is at backplane port, wherein the backplane port provides packets to the switched backplane;
• and
• means, responsive to the determining, for sending the congestion message to an ingress queue manager of a second blade across the backplane switch, the ingress queue manager having means for regulating, in response to the congestion message, a rate of dequeueing from an ingress queue of the second blade packets which are to be sent to a destination blade receiving packets from the port.

An article of manufacture comprising:

• a machine-readable storage medium having instructions stored thereon which, when executed by a processor cause the machine to
• dequeue packets from one or more ingress queues of a first blade to an egress queue of the first blade, wherein the egress queue is to send the packets to a port of the first blade, wherein the one or more ingress queues are to dequeue only packets which are to be sent to the port, wherein the first blade is coupled to a switched backplane;
• detect that the dequeueing of packets from the one or more ingress queues is contributing to a congestion of the egress queue;
• and
• in response to the detecting that the dequeueing of data packets from the one or more ingress queues is contributing to the congestion of the egress queue,
• reduce a rate of the dequeueing of packets from the one or more ingress queues,
• determine whether the port is a backplane port, wherein the backplane port provides packets to the switched backplane, and
• if the port is determined to be a backplane port,
• reduce a rate of dequeueing data packets from the egress queue to the port, wherein the data packets dequeued from the egress queue to the port are to be sent from the first blade to a destination blade via the switched backplane, and
• send a congestion message from the first blade to a second blade coupled to the switched backplane, the congestion message including an identifier of the port, wherein the second blade, based on the identifier of the port in the congestion message from the first blade, reduces a rate of dequeueing packets which are to be sent to the destination blade.