Apparatus and method for efficient detection and suppression of corrupted fibre channel frames in a protected transmission medium
An apparatus and method for detecting and suppressing corrupted data frames transported from a SONET network to a receiver utilizing the SOF frame indicator to manage the buffer-to-buffer credit count. By verifying the integrity of the SOF frame indicator prior to forwarding it to the client receiver the apparatus and method ensure that the buffer-to-buffer credit count integrity is maintained while avoiding the introduction of latency.
1. An apparatus for detecting and suppressing corrupted data frames transported from a SONET network to a receiver, said apparatus comprising:
a buffer-to-buffer credit counting means to control the flow of data frames, wherein said buffer-to-buffer credit counting means comprises:
(a) a frame de-encapsulation component configured for producing data frames compatible with said receiver from SONET frames input thereto, and outputting said receiver-compatible data frames;
(b) an idle frame signal generator configured for generating idle frame signals;
(c) a Start of Frame (SOF) indicator detector configured for detecting a Start of Frame indicator in each said receiver-compatible data frame output from said frame de-encapsulation component and determining whether said Start of Frame indicator is valid or corrupted, wherein said detector produces an output signal indicative of said determination; and
(d) a multiplexer configured for selecting for output to said receiver one of a first and a second signal input thereto on the basis of said output signal produced by said Start of Frame (SOF) indicator detector wherein said first input signal is a current said receiver-compatible data frame and said second input signal is said idle frame signal, said first input signal being selected when said output signal produced by said Start of Frame (SOF) indicator detector indicates that said Start of Frame indicator is valid and said second input signal being selected when said output signal produced by said Start of Frame (SOF) indicator detector indicates that said Start of Frame indicator is corrupted;
wherein said apparatus verifies said Start of Frame indicator in each of said receiver-compatible data frames and suppresses a receiver-compatible data frame responsive to corruption in said Start of Frame indicator prior to forwarding to said receiver to ensure buffer-to-buffer credit count integrity is maintained; and
wherein the integrity of the remainder of said receiver-compatible data frame is verified by the receiver.
2. An apparatus according to claim 1 wherein said receiver is for a fibre channel (FC) link.
3. A method for detecting and suppressing corrupted data frames transported from a SONET network to a receiver, said method comprising:
(a) receiving SONET frames from said SONET network and producing data frames compatible with said receiving from said received SONET frames;
(b) detecting a Start of Frame indicator in each said receiver-compatible data frame and determining whether said Start of Frame indicator is valid or corrupted; and
(c) selecting for output to said receiver a current said receiver-compatible data frame when said Start of Frame indicator is valid and selecting for output to said receiver said idle frame signal when said Start of Frame indicator is corrupted;
wherein said method utilizes a buffer-to-buffer credit counting means to control the flow of data frames;
wherein said method verifies said Start of Frame indicator in each of said receiver-compatible data frames and suppresses a receiver-compatible data frame responsive to corruption in said Start of Frame indicator prior to forwarding to said receiver to ensure buffer-to-buffer credit count integrity is maintained; and
wherein the integrity of the remainder of said receiver-compatible data frame is verified by the receiver.
4. A method according to claim 3 whereby said receiver is for a fibre channel (FC) link.