Patent ID: 8194534

Claim:
A rack-switch, comprising: a plurality of switches, each switch having a plurality of external ports, at least two of the external ports of each switch being inter-switch link (ISL) ports, one of the plurality of switches being a master node; a plurality of server blades, each server blade being in electrical communication with one of the plurality of switches; and a plurality of inter-switch links, each inter-switch link electrically connecting one ISL port of one of the plurality of switches to one ISL port of another of the plurality of switches, the plurality of inter-switch links interconnecting the switches of the plurality of switches such that the switches of the plurality of switches are daisy chained in a loop, wherein the master node detects the loop formed by the interconnected plurality of inter-switch links and, in response to detecting the loop, places one of the ISL ports of the master node into a blocked state in order to open the loop, the master node monitoring the loop while that one of its ISL ports is in the blocked state and unblocking that one blocked ISL port in response to detecting that the loop is broken, wherein the master node has a MAC (Media Access Control) address, transmits through one of the ISL ports of the master node a message containing a list of nodes in which the MAC address of the master node is first in the list of nodes, and detects the daisy-chain loop by receiving the message and recognizing the MAC address as first in the list of nodes contained in the message.