Non-blocking crossbar permutation engine with constant routing latency
First Claim
1. An N×
- N crossbar for routing packets from a set of N input ports to a set of N output ports, each packet having a header identifying one of said output ports as its destination, comprising;
a plurality of individual links which carry individual packets, each link having a link input end and a link output end;
a plurality of switches, each of said switches having at least top and bottom switch inputs connected to a corresponding pair of said link output ends and top and bottom switch outputs connected to a corresponding pair of link input ends, wherein each switch is connected to four different links and wherein different outputs of each one of at least some of said switches are connected through respective links to inputs of different switches, each of said switches having an exchange state which routes packets from said top and bottom switch inputs to said bottom and top switch outputs, respectively, and a bypass state which routes packets from said top and bottom switch inputs to said top and bottom switch outputs, respectively; and
a plurality of individual controller means governing respective ones of said switches for sensing from a header of a packet at each switch input the identity of the destination output port of the packet and selecting one of said exchange and bypass states as a function of the identity of said destination output port and as a function of the location of the corresponding switch relative to said destination output port.
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Abstract
The invention is embodied in an N×N crossbar for routing packets from a set of N input ports to a set of N output ports, each packet having a header identifying one of the output ports as its destination, including a plurality of individual links which carry individual packets, each link having a link input end and a link output end, a plurality of switches, each of the switches having at least top and bottom switch inputs connected to a corresponding pair of the link output ends and top and bottom switch outputs connected to a corresponding pair of link input ends, whereby each switch is connected to four different links, each of the switches having an exchange state which routes packets from the top and bottom switch inputs to the bottom and top switch outputs, respectively, and a bypass state which routes packets from the top and bottom switch inputs to the top and bottom switch outputs, respectively, a plurality of individual controller devices governing respective ones of the switches for sensing from a header of a packet at each switch input the identity of the destination output port of the packet and selecting one of the exchange and bypass states in accordance with the identity of the destination output port and in accordance with the location of the corresponding switch relative to the destination output port.
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Citations
27 Claims
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1. An N×
- N crossbar for routing packets from a set of N input ports to a set of N output ports, each packet having a header identifying one of said output ports as its destination, comprising;
a plurality of individual links which carry individual packets, each link having a link input end and a link output end; a plurality of switches, each of said switches having at least top and bottom switch inputs connected to a corresponding pair of said link output ends and top and bottom switch outputs connected to a corresponding pair of link input ends, wherein each switch is connected to four different links and wherein different outputs of each one of at least some of said switches are connected through respective links to inputs of different switches, each of said switches having an exchange state which routes packets from said top and bottom switch inputs to said bottom and top switch outputs, respectively, and a bypass state which routes packets from said top and bottom switch inputs to said top and bottom switch outputs, respectively; and a plurality of individual controller means governing respective ones of said switches for sensing from a header of a packet at each switch input the identity of the destination output port of the packet and selecting one of said exchange and bypass states as a function of the identity of said destination output port and as a function of the location of the corresponding switch relative to said destination output port. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13)
- N crossbar for routing packets from a set of N input ports to a set of N output ports, each packet having a header identifying one of said output ports as its destination, comprising;
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14. A non-blocking crossbar, comprising at least a pair of cascaded permutation engines, each of said permutation engines comprising an N×
- N crossbar for routing packets from a set of N input ports to a set of N output ports, each packet having a header identifying one of said output ports as its destination, comprising;
a plurality of individual links which carry individual packets, each link having a link input end and a link output end; a plurality of switches, each of said switches having at least top and bottom switch inputs connected to a corresponding pair of said link output ends and top and bottom switch outputs connected to a corresponding pair of link input ends, wherein each switch is connected to four different links and wherein different outputs of each one of at least some of said switches are connected through respective links to inputs of different switches, each of said switches having an exchange state which routes packets from said top and bottom switch inputs to said bottom and top switch outputs, respectively, and a bypass state which routes packets from said top and bottom switch inputs to said top and bottom switch outputs, respectively; and a plurality of individual controller means governing respective ones of said switches for sensing from a header of a packet at each switch input the identity of the destination output port of the packet and selecting one of said exchange and bypass states as a function of the identity of said destination output port and as a function of the location of the corresponding switch relative to said destination output port, wherein the output ports of one of said permutation engines is connected to respective ones of the input ports of the other of said permutation engines. - View Dependent Claims (15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27)
- N crossbar for routing packets from a set of N input ports to a set of N output ports, each packet having a header identifying one of said output ports as its destination, comprising;
Specification