IPC분류정보
국가/구분 |
United States(US) Patent
등록
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국제특허분류(IPC7판) |
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출원번호 |
UP-0894586
(2004-07-20)
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등록번호 |
US-7630384
(2009-12-16)
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발명자
/ 주소 |
- Dropps, Frank R
- Kohlwey, Ernest G
- Ross, Edward C.
- Owen, Mark A.
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출원인 / 주소 |
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대리인 / 주소 |
Klein, O'Neill & Singh, LLP
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인용정보 |
피인용 횟수 :
0 인용 특허 :
247 |
초록
▼
A method and system for distributing credit using a fiber channel switch element is provided. The switch element includes, a wait threshold counter that is used to set up a status for a port that has to wait for certain duration to send a frame due to lack of buffer to buffer credit; a credit module
A method and system for distributing credit using a fiber channel switch element is provided. The switch element includes, a wait threshold counter that is used to set up a status for a port that has to wait for certain duration to send a frame due to lack of buffer to buffer credit; a credit module that controls buffer to buffer credit for a transmit segment of the fiber channel switch element; and a virtual lane credit module with a counter that is incremented every time a frame assigned to a virtual lane is sent and decreased every time a VC_RDY is received. The method includes, determining if a VC_RDY primitive is received; and allocating credit to a virtual lane that is not at its maximum credit, after the VC_RDY primitive is received.
대표청구항
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What is claimed is: 1. A method for distributing credit in a fibre channel switch element, comprising: (a) determining if (i) a port for the fibre channel switch element using a plurality of virtual lanes has received a flow control link primitive, R_RDY instead of a VC_RDY, a flow control link pri
What is claimed is: 1. A method for distributing credit in a fibre channel switch element, comprising: (a) determining if (i) a port for the fibre channel switch element using a plurality of virtual lanes has received a flow control link primitive, R_RDY instead of a VC_RDY, a flow control link primitive used for credit in virtual lanes; and (ii) if the fibre channel switch element has internally generated the primitive, R_RDY for recovering lost credit due to loss of data frames; wherein each virtual lane is identified by an identification number; (b) determining if a first virtual lane from among the plurality of virtual lanes has reached a maximum credit value allocated for the first virtual lane; (c) if the first virtual lane has reached the maximum credit value, iteratively determining if another virtual lane for the port has not reached a maximum allocated credit value; and allocating the recovered lost credit to a virtual lane from among the plurality of virtual lanes that has not reached the maximum allocated credit value; (d) if an R_RDY primitive is not received or generated for credit recovery in step (a); determining if the primitive, VC_RDY indicating that credit is available at a virtual lane at a destination port has been received by the port; (e) determining if the virtual lane identified by the VC_RDY received in step (d) has already reached its maximum allocated credit; and (f) iteratively analyzing each of the remaining plurality of virtual lanes and applying the credit based on the received VC_RDY in step (d) to a virtual lane that has not reached a maximum allocated credit even if a VC_RDY virtual lane identification number indicates that credit be allocated to a different virtual lane. 2. The method of claim 1, wherein a processor for the fibre channel switch element resets a link if one or more of credit loss and frame loss exceeds a threshold value. 3. A method for distributing credit in a fibre channel system having a fibre channel switch element, comprising: (a) detecting lost credit at a port for the fibre channel switch element if fewer than expected VC_RDYs and R_RDYs are received between BB_SCrs; wherein VC_RDY is a link primitive indicating credit for a virtual lane of a port supporting a plurality of virtual lanes; wherein R_RDY is a link primitive indicating credit at a receive segment of a port, wherein BB_SCr is a link primitive used for tracking lost credit in the fibre channel system; and wherein each of the plurality of virtual lanes supported by the port in step (a) is assigned an identification number and is allocated a maximum credit value; (b) iteratively determining if a virtual lane from among the plurality of virtual lanes for the port has not reached its maximum allocated credit value; and (c) allocating the recovered lost credit from step (a) to the virtual lane from among the plurality of virtual lanes, that has not reached the maximum allocated credit value; wherein the recovered lost credit is allocated to a virtual lane that is different from the virtual lane identified by the VC_RDY, if the identified virtual lane has reached the maximum allocated credit value. 4. The method of claim 3, further comprising: determining if a BB_SCr, a link primitive, is lost or extra credit is received if a R_RDY or VC_RDY is received when a BB_SCr is expected; and setting a status bit to indicate if a BB_SCr was lost or an extra R_RDY or VC_RDY is received. 5. A fibre channel switch element for routing fibre channel frames, comprising: a plurality of ports for receiving and transmitting frames, each port including a transmit segment and a receive segment; a wait threshold counter that monitors a duration a transmit segment of a port has to wait for sending a frame due to lack of buffer to buffer credit and if the duration exceeds a programmable threshold value, the wait threshold counter generates a status signal; a credit module that controls buffer to buffer credit for a transmit segment of a port; and a virtual lane credit module with a counter that is incremented every time a frame assigned to a virtual lane is sent and decreased every time a VC_RDY, a link primitive indicating that credit is available at a virtual lane at a destination port has been received by the port is received; wherein for allocating recovered lost credit among a plurality of virtual lanes, based on a received R_RDY, a VC_RDY and a R_RDY generated by the switch element for lost data frames, the fibre channel switch element (a) determines if a first virtual lane from among the plurality of virtual lanes supported by a port at the fibre channel switch element has reached a maximum credit value allocated for the first virtual lane; (b) iteratively determines if another virtual lane for the port has not reached a maximum allocated credit value; and (c) allocates the recovered lost credit to a virtual lane from among the plurality of virtual lanes, that has not reached the maximum allocated credit value; and wherein the virtual lane to which credit is allocated is different from the virtual lane identified by the VC_RDY used for the lost credit, if the identified virtual lane has reached its maximum allocated value. 6. The fibre channel switch element of claim 5 further comprising: a logic module that generates a status signal if loss of more than a threshold number of frame credit due to loss of R_RDY and VC_RDY is detected, wherein R_RDY is a link primitive indicating available credit at a receive segment of a port. 7. The fibre channel switch element of claim 6, wherein the threshold number is programmable or fixed. 8. The fibre channel switch element of claim of 6, wherein if lost frames are detected, then the logic module generates an equivalent number of R_RDY link primitives that should have been received and sends the generated R_RDY link primitives to a device on another end of a link. 9. The fibre channel switch element of claim 6, wherein the fibre channel switch element firmware resets a link if loss of more than a threshold number of frame credit is detected. 10. The fibre channel switch element of claim 6, wherein the fibre channel switch element firmware resets a link if loss of more than a threshold number of R_RDY primitive or VC_RDY primitive is detected. 11. The fibre channel switch element of claim 6, wherein the fibre channel switch element firmware provides statistics when a loss of more than a threshold number of frame or credit is detected; and the statistics are used for trend analysis on a link. 12. The fibre channel switch element of claim 6, wherein the fibre channel switch element firmware provides statistics if loss of more than a threshold number of R_RDY primitive or VC_RDY primitive is detected; and the statistics are used for trend analysis on a link.
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