Patent ID: 7496700

Claim:
A method of serial advanced technology attachment tunneling protocol (STP) flow control in a serial attached small computer system interface (SAS) expander, said method comprising: when primitives of a first type are received by said SAS expander, forwarding said primitives of said first type through an ingress buffer and sending primitives of a second type on an egress buffer; when said primitives of said first type are not received by said SAS expander, but said primitives of said second type are received, discarding a data word incoming to said SAS expander; when neither said primitives of said first type nor said primitives of said second type are received by said SAS expander and a fill level of said ingress buffer is not greater than a threshold, writing said data word to said ingress buffer; when neither said primitives of said first type nor said primitives of said second type are received by said SAS expander and said fill level of said ingress buffer is greater than said threshold and said data word is a repeatable data word, discarding said data word incoming to said SAS expander; and when neither said primitives of said first type nor said primitives of said second type are received by said SAS expander and said fill level of said ingress buffer is greater than said threshold and said data word is not a repeatable data word, writing said data word to said ingress buffer; wherein said primitives of said first type and said primitives of said second type are interlocking relative to one another.