Patent ID: 7633861

Claim:
A method of bounding cell reorder buffer depth, comprising: determining whether a reorder buffer that is associated with a switch fabric exceeds a depth limit, wherein: the depth limit is than the size of the reorder buffer; and the reorder buffer is one of a plurality of reorder buffers, each of the plurality of reorder buffers being configured to store one or more cells of a respective class having a respective priority level and being received from a respective source port via a respective switch plane; and in the event that the reorder buffer exceeds the depth limit, sending backpressure with respect to the respective source port associated with the reorder buffer by including in a subsequent cell being sent into the switch fabric source based backpressure information that pertains to the respective source port, the source based backpressure information being configured to temporarily stop the respective source port from sending traffic with the respective priority associated with the reorder buffer via the respective switch plane associated with the reorder buffer, wherein: the source based back pressure information is stored in a multi-purpose reserved field in the subsequent cell; and the multi-purpose reserved field is re-used, in the event that an egress link is unavailable, to include destination based backpressure information configured to signal that the egress link is unavailable and to stop other ports from sending data to the unavailable egress link.