Method and system for congestion control based on optimum bandwidth allocation in a fibre channel switch
View Patent ↗A method and system for optimizing bandwidth allocation in a fiber channel network having a fiber channel switch element, is provided. The switch element includes, a port control module having a receive and transmit segment, wherein the transmit segment is programmed to block frame transmission from a particular frame source port for a certain duration based on a programmable threshold value. The method includes, enabling a bandwidth limitation counter; and programming the threshold value for blocking frame transmission from a frame source port for a certain duration and during this duration, other source ports may be chosen for frame transmission. After a frame is transmitted from a source port, a tag valid blocking from the same source port is used to block frame transmission. A quality of service register is used to store the threshold value and the threshold value is programmable.
1. A method for optimizing bandwidth allocation in a fibre channel network having a fibre channel switch element, comprising:
enabling a first bandwidth limitation counter in bandwidth limiting logic, the first bandwidth limitation counter being configured to measure a first duration corresponding to an amount of time to pass a full-length frame;
enabling a second bandwidth limitation counter in the bandwidth limiting logic, the second bandwidth limitation counter being configured to count from zero to a threshold value x;
sending a frame from a source port and generating a frame depart signal denoting that the source port has completed transfer of the frame;
the second bandwidth limitation counter, upon receiving the frame depart signal, counting an interval from zero to x;
wherein a signal from the first bandwidth limitation counter increments the second bandwidth limitation counter; and
during the interval frame transmission from the source port is blocked but other source ports may be chosen for frame transmission.
2. The method of claim 1 , wherein blocking frame transmission from the source port comprises blocking a valid bit in a transmit tag register of the bandwidth limiting logic.
3. The method of claim 1 , further comprising the step of programming the value of x in a quality of service register.
4. The method of claim 1 further comprising a transmit credit signal stopping the first bandwidth limitation counter from counting when no transmit credit is available.
5. The method of claim 1 , further comprising the second bandwidth limitation counter receiving a bandwidth limiting enable signal to enable bandwidth limiting.
6. Bandwidth limiting logic in a transmit segment of a fibre channel switch element, comprising:
a first bandwidth limitation counter configured to measure a first duration corresponding to an amount of time to pass a full-length frame; and
a second bandwidth limitation counter configured to count an interval from zero to a threshold value x upon receiving a frame depart signal denoting that a source port has completed transfer of a frame, and during the interval frame transmission from the source port is blocked but other source ports may be chosen for frame transmission;
wherein the first bandwidth limitation counter is configured to generate a signal that increments the second bandwidth limitation counter.
7. The bandwidth limiting logic of claim 6 , wherein during the interval the transmit segment may select another source port for frame transmission.
8. The bandwidth limiting logic of claim 6 , further comprising a programmable register configured to store the programmable threshold value x.
9. The bandwidth limiting logic of claim 6 , wherein a value of the second bandwidth limitation counter is compared to the threshold value x to determine whether the source port should be blocked.
10. The bandwidth limiting logic of claim 6 , further comprising a transmit credit signal configured to stop the first bandwidth limitation counter from counting when no transmit credit is available.
11. The bandwidth limiting logic of claim 6 , further comprising a bandwidth limiting enable signal configured to enable bandwidth limiting.