Switching device

A switching device for transferring data packets, comprising:

• one or more source line cards, each including a request generator to generate a request signal to be transmitted in order to obtain an authorization to transmit data;
• one or more destination line cards, each including a grant generator to generate and send back a grant signal to a source line card in response to the request signal received at a destination line card to authorize the source line card to transmit a data cell to the destination line card;
• and
• a switching fabric coupled to the source line card and the destination line card, the switching fabric being configured to receive and transmit the request signal, the grant signal, and the data cell to the appropriate line cards, where the switching fabric is configured to transmit at least two of a request signal, a grant signal, or a data cell together in a single data transfer unit.

In a switching device having a plurality of line cards and a switch fabric therebetween for transferring data packets, a switch fabric comprising:

• a plurality of first stage crossbars in a first stage, each first stage crossbar having a plurality of input ports and a plurality of output ports, each input port having a first request spray engine to receive a plurality of request signals associated with a destination line card and spray the request signals to different ones of the output ports in the same first stage crossbar;
• a plurality of second stage crossbars in a second stage, each second stage crossbar having a plurality of input ports and a plurality of output ports, each input port having a second request spray engine to receive one of the request signals from one of the first stage crossbars and send the request signal to one of the output ports in the same second stage crossbar;
• and
• a plurality of third stage crossbars in a third stage, each third stage crossbar having a plurality of input ports and a plurality of output ports, each input port having a third request spray engine to receive one of the request signals from one of the second stage crossbars and send the request signal to one of the output ports in the same third stage crossbar.

A switching device for transferring data, comprising:

• a source line card;
• a destination line card including a grant generator to generate and transmit a grant signal to the source line card to authorize the source line card to transfer data to the destination line card;
• the source line card including a data cell transmitter to transfer a data cell to the destination line card upon receiving the grant signal at the source line card;
• and
• a switching fabric coupled to the source line card and the destination line card for receiving the grant signal from the destination line card and switching the grant signal to the source line card, and for receiving the data cell from the source line card and switching the data cell to the destination line card, where the switching fabric is configured to transmit a grant signal and a data cell together in a single data transfer unit.

A method for transferring data between line cards in a router, the router having a plurality of line cards and a switching fabric coupled to the line cards, the method comprising:

• transmitting a request signal from a source line card to a destination line card through the switching fabric;
• upon receiving the request signal at the destination line card, sending a grant signal from the destination line card to the source line card responsive to the request signal to authorize the source line card to transfer data to the destination line card;
• transferring a data cell from the source line card to the destination line card in response to the grant signal received at the source line card;
• and
• transferring, by the switching fabric, at least two of a request signal, a grant signal, or a data cell together in a single data transfer unit.

In a switching device having a plurality of line cards and a switching fabric therebetween for transferring data packets, where each line card includes an input section including one or more input ports and an output section including one or more output ports, a method for controlling the transfer of a data packet through the switching device comprising:

• generating a request flow control message at a source line card to request authorization for a transfer of the data packet from the source line card to the destination line card;
• transferring the request flow control message from the input section of the source line card to the output section of the destination line card using the switching fabric;
• generating a grant flow control message at a destination line card for the data packet;
• transferring the grant flow control message from the output section of the destination line card to the input section of the destination line card;
• transferring the grant flow control message from the input section of the destination line card to the output section of the source line card using the switching fabric;
• receiving the grant flow control message on the output section of the source line card and transferring the grant flow control message to the input section of the source line card;
• and
• upon receipt of the grant flow control message at the input section of the source line card, transferring the data packet from the source line card to the destination line card using the switching fabric.

In a switching device having a plurality of line cards and a switching fabric therebetween for transferring data packets, where each line card includes an input section including one or more input ports and an output section including one or more output ports, a method for controlling the transfer of a data packet through the switching device comprising:

• generating flow control messages at the source line card and destination line card to authorize a transfer of the data packet from the source line card to the destination line card;
• and
• transferring the flow control messages between the source and destination line cards including
• transferring flow control messages from the input section of a line card to the output section of a different line card using the switching fabric, and
• transferring flow control messages from the output section of a line card to the input section of a same line card without using the switching fabric.

A switching device for transferring data packets, comprising:

• one or more source line cards, each including a request generator to generate a request signal to be transmitted in order to obtain an authorization to transmit data;
• one or more destination line cards, each including a grant generator to generate and send back a grant signal to a source line card in response to the request signal received at the destination line card to authorize the source line card to transmit a data cell to the destination line card;
• and
• a plurality of planes of switching elements coupling the one or more source line cards and the one or more destination line cards, each plane being connected to the one or more source line cards and the one or more destination line cards and being configured to receive and transmit the request signal, the grant signal, and the data cell to the appropriate line cards.

In a switching device including one or more source line cards and destination line cards, the switching device for transferring data packets through a network, a method for recovering from a failure in the switching device comprising:

• providing plural switching planes between each source line card and destination line card;
• generating flow control messages for authorizing a transfer of a packet from a source line card to a destination line card;
• spraying the flow control messages over each of the plural switching planes;
• and
• spraying data packets over switching planes on which flow control authorization messages are received.