Multi-level flow control
Various methods, systems, and apparatuses can be used to control flow in an ethernet environment. In some implementations, methods can include receiving a flow of ethernet frames at a first device via an ethernet switch, determining that a buffer at the first device exceeds a threshold for an incoming flow, generating an initial pause frame operable to pause only a second device, and transmitting the initial pause frame to the ethernet switch.
1. A computer-implemented method, comprising:
receiving a flow of ethernet frames at a first device via an ethernet switch;
determining that a buffer at the first device exceeds a first threshold for an incoming flow;
generating a first initiate pause frame operable to pause only a second device, the second device being the device that initiated the flow of ethernet frames that caused the buffer to exceed the first threshold, the first initiate pause frame comprising a substantially conventional pause frame but operating to pause the originating device at a link layer using a destination media access control address and length/type field within the first initiate pause frame that is operable to pass through intermediate switching and cause the second device to immediately stop sending data;
transmitting the first initiate pause frame to the ethernet switch;
continuing to receive ethernet frames associated with the flow from the ethernet switch based upon ethernet frames already received at the ethernet switch prior to the second device suspending transmission of the ethernet frames associated with the flow;
continuing to monitor the buffer; and
if the buffer exceeds a second threshold, transmitting a second initiate pause frame addressed directly to the ethernet switch.
2. The computer-implemented method of claim 1 , wherein the ethernet switch is operable to forward the first initiate pause frame to the second device.
3. The computer-implemented method of claim 2 , wherein the second device is operable to parse the first initiate pause frame and to suspend transmission of ethernet frames associated with the flow to the first device.
4. The computer-implemented method of claim 1 , wherein the first initiate pause frame includes a field operable to identify a duration during which the transmission of ethernet frames associated with the flow should be suspended.
5. The computer-implemented method of claim 4 , further comprising transmitting a first terminate pause frame identifying a duration of the pause to be zero, wherein receipt of the first terminate pause frame causes the second device to resume transmitting ethernet frames associated with the flow.
6. The computer-implemented method of claim 1 , wherein the ethernet switch is operable to suspend transmission of ethernet frames associated with the flow to the first device responsive to receipt of the second initiate pause frame from the first device.
7. The computer-implemented method of claim 1 , wherein the second initiate pause frame includes a duration during which the ethernet switch should suspend transmission of ethernet frames associated with the flow.
8. The computer-implemented method of claim 7 , further comprising transmitting a second terminate pause frame identifying a duration of the pause to be zero, wherein receipt of the second terminate pause frame causes the ethernet switch to resume transmitting ethernet frames associated with the flow.
9. The computer-implemented method of claim 1 , wherein the first and second devices and ethernet switch comprise integrated circuits integrated into a single apparatus, and being operable to communicate with each other using an ethernet protocol.
10. A system, comprising:
a first integrated module operable to receive a flow of ethernet frames via an integrated ethernet switch;
fill level logic operable to determine that a buffer at the first integrated module exceeds a first threshold for an incoming flow;
a pause generator operable to generate a first initiate pause frame operable to pause only a second integrated module, the second integrated module being an initiator of the flow of ethernet frames that caused the buffer to exceed the first threshold, the first initiate pause frame comprising a substantially conventional pause frame but operating to pause the originating device at a link layer using a destination media access control address and length/type field within the first initiate pause frame that is operable to pass through intermediate switching and cause the second device to immediately stop sending data;
wherein the first integrate module is operable to cause the first initiate pause frame to be transmitted to the integrated ethernet switch;
wherein the buffer is operable to continue to receive ethernet frames associated with the flow from the integrated ethernet switch based upon ethernet frames already received at the integrated ethernet switch prior to the second integrated module suspending transmission of the ethernet frames associated with the flow;
wherein the fill level logic is operable to continue to monitor the buffer, and instruct the pause generator to generator a second initiate pause frame addressed directly to the integrated ethernet switch if the buffer exceeds a second threshold.
11. The system of claim 10 , wherein the integrated ethernet switch is operable to forward the first initiate pause frame to the second integrated module.
12. The system of claim 11 , wherein the second integrated module is operable to parse the first initiate pause frame and to suspend transmission of ethernet frames associated with the flow to the first integrated module.
13. The system of claim 10 , wherein the first initiate pause frame includes a field operable to identify a duration during which the transmission of ethernet frames associated with the flow should be suspended.
14. The system of claim 13 , wherein the pause generator is further operable to transmit a first terminate pause frame, the first terminate pause frame being identical to the first initiate pause frame except that it identifies a duration of the pause to be zero; wherein receipt of the first terminate pause frame causes the second integrated module to resume transmitting ethernet frames associated with the flow.
15. The system of claim 10 , wherein the integrated ethernet switch is operable to suspend transmission of ethernet frames associated with the flow to the first integrated module responsive to receipt of the second initiate pause frame from the first integrated module.
16. The system of claim 10 , wherein the second initiate pause frame includes a duration during which the integrated ethernet switch should suspend transmission of ethernet frames associated with the flow.
17. The system of claim 16 , wherein the first integrated module is further operable to transmit a second terminate pause frame identifying a duration of the pause to be zero, wherein receipt of the second terminate pause frame causes the integrated ethernet switch to resume transmitting ethernet frames associated with the flow.