Granted Patent B2

US 9,497,141 · App. 14/624,207 · Granted Nov 15, 2016

Abstract

Claims (50)

1. In a network having a plurality of switch points, each switch point having a plurality of ports for transmitting packets from a source device to a destination device, and each switch point having both a main multi-stage pipeline between ports of the plurality of ports and a look-ahead pipeline between the ports of the plurality of ports, wherein the look-ahead pipeline has fewer pipeline stages than the main multi-stage pipeline, a method comprising:

receiving a packet and look-ahead information corresponding to the packet at a port of a switch point;

generating a first stage look-ahead request from the look-ahead information;

determining that the first stage look-ahead request is not granted;

generating a second stage look-ahead request from the first stage look-ahead request in response to the first stage look-ahead request not being granted;

determining that the second stage look-ahead request is granted;

in response to the second stage look-ahead request being granted, transmitting the packet through the switch point using the look-ahead pipeline; and in response to the second stage look-ahead request not being granted:

generating a third stage look-ahead request from the second stage look-ahead request;

determining that the third stage look-ahead request is not granted; and

transmitting the packet through the switch point using the main multi-stage pipeline.

2. The method of claim 1 , wherein transmitting the packet through the main multi-stage pipeline comprises:

storing the packet in a storage element of a virtual channel of the switch point;

arbitrating for access to the virtual channel;

allocating a switch traversal path through the switch point; and

transmitting the packet through the allocated switch traversal path.

3. The method of claim 1 , wherein transmitting the packet through the main multi-stage pipeline further comprises transmitting the packet through the main multi-stage pipeline in four clock cycles, and transmitting the packet through the look-ahead pipeline comprises transmitting the packet through the look-ahead pipeline in less than four clock cycles.

4. The method of claim 1 , wherein the plurality of switch points are connected together in a mesh configuration.

5. The method of claim 1 , wherein the packet begins transiting the main multi-stage pipeline concurrently with generating the first stage look-ahead request.

6. The method of claim 1 , wherein in response to one of the first stage look-ahead request and second stage look-ahead request being granted, the transiting of the main multi-stage pipeline is cancelled.

7. A method comprising: receiving a packet and look-ahead information corresponding to the packet at a port of a switch point, the switch point being one of a plurality of switch points configured as network; the packet being routed through the switch point between a source and a destination;

generating a first stage look-ahead request from the look-ahead information;

determining that the first stage look-ahead request is not granted;

generating a second stage look-ahead request from the first stage look-ahead request in response to the first stage look-ahead request not being granted;

determining that the second stage look-ahead request is granted; and

transmitting the packet through the switch point using a look-ahead pipeline in response to the second stage look-ahead request being granted, the look-ahead pipeline having fewer pipelining stages than a main multi-stage pipeline of the switch point;

generating a third stage look-ahead request from the second stage look-ahead request;

in response to determining that the third stage look-ahead request is granted, transmitting the packet through the switch point using the look-ahead pipeline; and

in response to determining that the third stage look-ahead request is not granted, transmitting the packet through the switch point using the main multi-stage pipeline.

8. The method of claim 7 , wherein transmitting the packet through the main multi-stage pipeline comprises:

storing the packet in a storage element of the switch point;

arbitrating a portion of a path between the source and the destination;

allocating a switch traversal path through the switch point; and

transmitting the packet through the allocated switch traversal path.

9. The method of claim 7 , wherein the plurality of switch points are connected together to form a network in a mesh configuration.

10. The method of claim 7 , wherein the packet begins transiting the main multi-stage pipeline concurrently with generating the first stage look-ahead request.

11. The method of claim 7 , wherein in response to the first stage look-ahead request being granted, the transiting of the main multi-stage pipeline is cancelled.

12. The method of claim 7 , wherein the switch point is implemented on a single integrated circuit die.

13. A switch point having a plurality of ports, the switch point comprising:

a main multi-stage pipeline coupled to the plurality of ports, the multi-stage pipeline having a plurality of pipelining stages for transmitting a packet of information between a selected input port and a selected output port of the plurality of ports; and

a look-ahead pipeline coupled to the plurality of ports, the look-ahead pipeline having fewer pipelining stages than the main multi-stage pipeline, the look-ahead pipeline for transmitting the packet of information between the input port and the selected output port,

wherein the look-ahead pipeline having a first look-ahead stage, a second look-ahead stage, and a third look-ahead stage, the first look-ahead stage for providing a first look-ahead request, the packet of information being transmitted through the look-ahead pipeline in response to the first look-ahead request being granted, the second look-ahead stage for providing a second look-ahead request, the second look-ahead request for requesting use of the look-ahead pipeline for the packet of information in response to the first look-ahead request not being granted, and the third look-ahead stage for providing a third look-ahead request, the third look-ahead request being provided in response to the first and second look-ahead requests not being granted, wherein the packet of information being transmitted through the look-ahead pipeline in response to the third look-ahead request being granted, and wherein the packet of information being transmitted through the main multi-stage pipeline in response to the third look-ahead request not being granted.

14. The switch point of claim 13 , wherein the main multi-stage pipeline further comprises:

a plurality of storage elements;

arbitrator coupled to the plurality of storage elements;

a plurality of switches for interconnecting the plurality of ports, access to the plurality of switches by the packet being arbitrated for using the arbitrator; and

allocation logic coupled to the plurality of switches, the allocation logic for allocating use of the plurality of switches for the packet.

15. The switch point of claim 13 , wherein the look-ahead pipeline further comprises the first and second look-ahead stages being coupled in series to the plurality of switches.

16. The switch point of claim 14 , wherein the allocation logic further comprises:

fast allocation and arbitrator logic for allocating use of the plurality of switches when the packet is being transmitted using the look-ahead pipeline; and

slow allocation and arbitrator logic for allocating use of the plurality of switches when the packet is being transmitted using the main multi-stage pipeline.

Assignments (14)