Transferring packets from a primary buffer of an ingress port to an associated secondary buffer if the secondary buffer satisfies a predetermined criterion.

摘要

A switching device comprising at least one ingress port and at least one egress port. The switching device is arranged to receive data packets through said at least one ingress port and to forward received data packets to respective ones of said at least one egress port. The switching device further comprises a primary buffer (queue) arranged to store data packets received via at least one of said at least one ingress ports and a secondary buffer (queue) associated with the primary buffer. The switching device is adapted to select a data packet from said primary buffer and if but only if said secondary buffer satisfies a least one first predetermined criterion, transfer said selected data packet to said secondary buffer. By moving data packets from the primary buffer to the secondary buffer, the switching device may have a greater number of data packets from which to select. This is beneficial from the point of view of mitigating head of line blocking issues i.e. avoiding congestion. Aspects of the invention include the predetermined criterion being that the secondary buffer is empty, or wherein the secondary buffer contains data packets to be forwarded to a particular egress port (when the switching device has determined an egress port to which a selected data packet is to be forwarded). Further aspects of the invention include a congestion buffer associated with the primary buffer.