Which two ELS request and reply sequences advertise buffer-to-buffer credits between Fibre Channel devices? (Choose two.)
A. ESC
B. FLOGI
C. PLOGI
D. PRLI
Explanation:
One Comment on “Which two ELS request and reply sequences advertise buffer-to-buffer credits between Fibre Channel devices?”
alexeysays:
BB_credits are used by Class 2 and Class 3 service and rely on the receiver sending back
receiver-readies (R_RDY) to the transmitter. As was previously discussed, node pairs
communicate their number of credits available during FLOGI/PLOGI. This value is used by the
transmitter to track the consumption of receive buffers and pace transmissions if necessary.
FICON directors track the available bb_credits in the following manner:
• before any data frames are sent, the transmitter sets a counter equal to the BB_credit
value communicated by its receiver during FLOGI,
• for each data frame sent by the transmitter, the counter is decremented by one,
• upon receipt of a data frame, the receiver sends a status frame (R_RDY) to the
transmitter indicating that the data frame was received and the buffer is ready to receive
another data frame, and
• for each R_RDY received by the transmitter, the counter is incremented by one.
BB_credits are used by Class 2 and Class 3 service and rely on the receiver sending back
receiver-readies (R_RDY) to the transmitter. As was previously discussed, node pairs
communicate their number of credits available during FLOGI/PLOGI. This value is used by the
transmitter to track the consumption of receive buffers and pace transmissions if necessary.
FICON directors track the available bb_credits in the following manner:
• before any data frames are sent, the transmitter sets a counter equal to the BB_credit
value communicated by its receiver during FLOGI,
• for each data frame sent by the transmitter, the counter is decremented by one,
• upon receipt of a data frame, the receiver sends a status frame (R_RDY) to the
transmitter indicating that the data frame was received and the buffer is ready to receive
another data frame, and
• for each R_RDY received by the transmitter, the counter is incremented by one.
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