Patent ID: 8797843

Claim:
A method of operating a physical switching network including an upper tier having multiple physical master switches and a lower tier including a plurality of physical lower tier follower switches, the method comprising: coupling inter-switch ports of each of the lower tier follower switches to each of multiple physical master switches at the upper tier by a respective one of multiple links and configuring each of the lower tier follower switches in flow through mode; at each of the multiple master switches, implementing on each of a plurality of master switch ports a plurality of virtual ports each corresponding to a respective one of a plurality of data ports at the lower tier follower switch coupled to that master switch port, wherein the plurality of data ports provide physical interfaces for data traffic ingressing and egressing the switching network; each of the plurality of lower tier follower switches maintaining a respective egress port mapping indicating which of its plurality of data ports transmits egress data traffic through each of its inter-switch ports to the multiple master switches; and in response to failure of one of the multiple links coupling a particular lower tier follower switch among the plurality of lower tier follower switches to a particular master switch among the multiple master switches, the particular lower tier follower switch updating its egress port mapping to redirect egress data traffic from the particular master switch to at least one other of the multiple master switches.