Technique for computing pathways in a multi-stage switch fabric through exploitation of symmetrical links

A switch fabric for switching data traffic according to a plurality of links, comprising:

• a) input stage means including a plurality of switching elements having external ports;
• b) output stage means including a plurality of switching elements having external ports;
• c) least one intermediate stage means including a plurality of switching element means;
• d) a switch fabric controller means wherein:
• i) said switch fabric includes a link database means including information about the plurality of links;
• ii) said switch fabric controller means is operative to search said link database means to identify symmetrical links;
• and
• iii) said switch fabric controller is operative for establishing internal pathways between said input stage means and said output stage means through said at least one intermediate stage means, wherein at least two symmetrical links identified by the searching are realized using a common switching element means of said at least one intermediate stage means.

A switch fabric controller for use with a switch fabric including:

• a) an input stage including a plurality of switching elements having external input ports;
• b) an output stage including a plurality of switching elements having external output ports;
• c) at least one intermediate stage including a plurality of switching element;
• d) said switch fabric controller, comprising:
• i) a link database including information about the plurality of links;
• ii) said switch fabric controller is operative to search said link database to identify symmetrical links;
• and
• iii) said switch fabric controller is operative for establishing internal pathways between the input stage and the output stage through the at least one intermediate stage, wherein at least two symmetrical links identified by the searching are realized using a common switching element of the at least one intermediate stage.

A computer readable storage medium including a program element for execution by a CPU to compute an internal pathway map for a switch fabric that includes:

• a) an input stage including a plurality of switching elements having external input ports;
• b) an output stage including a plurality of switching elements having external output ports;
• c) at least one intermediate stage including a plurality of switching elements;
• d) a link database including information about the plurality of links according to which data traffic is to be switched by the switch fabric;
• e) said program element, comprising:
• i) a searching module for searching the link database to identify pairs of symmetrical links;
• ii) a processing module for computing internal pathways between the input stage and the output stage, the computing characterized in that at least two symmetrical links identified by the searching are realized using a common switching element of the at least one intermediate stage.

In a method for switching data traffic according to a plurality of links through a switch fabric, having:

• a) an input stage including a plurality of switching elements having external input ports;
• b) an output stage including a plurality of switching elements having external output ports;
• c) at least one intermediate stage including a plurality of switching elements;
• and
• d) a link database including information about the plurality of links according to which data traffic is to be switched by the switch fabric;
• e) said method, including:
• i) searching the link database to identify pairs of symmetrical links;
• ii) establishing internal pathways between the input stage and the output stage through the at least one intermediate stage, wherein at least two symmetrical links identified by the searching are realized over a common switching element of the at least one intermediate stage.

A switch fabric for switching data traffic according to a plurality of links, comprising:

• a) an input stage including a plurality of switching elements having external input ports;
• b) an output stage including a plurality of switching elements having external output ports;
• c) at least one intermediate stage including a plurality of switching elements;
• d) a switch fabric controller wherein:
• i) said switch fabric controller is operative for establishing an internal pathway for a working link through said input stage, said output stage and through said at least one intermediate stage;
• ii) said switch fabric controller is operative for establishing an internal pathway for a protection link protecting said working link through said input stage, said output stage and said at least one intermediate stage;
• iii) wherein said working link and said protection link are established through at least one common switching element of said input stage, said output stage and said at least one intermediate stage;
• iv) in case of a failure of the working link said switch fabric controller is operative to perform a switching event at said at least one common switching element to direct data traffic on the working link to the protection link.