• Must be unique in the context of the S_ID while the sequence is open
• Can be reused after the sequence is complete
– SEQ_CNT identifies the position of the frame in the sequence
• Used to verify in-order delivery, missing frames
DF_CTL
S_ID D_ID
F_CTL
SEQ_CNT
RX_ID
The N_Port that is sending the sequence is called the Sequence Initiator, and the N_port that receives the sequence is called the Sequence Recipient. The SEQ_ID field is an eight-bit field that is used by the Sequence Initiator and Responder to identify all frames in a given sequence:
• The Sequence Initiator assigns a SEQ_ID to the sequence and uses the same SEQ_ID for every frame in the sequence.
• As long as the sequence is open, SEQ_ID must be unique within the context of the sequence initiator (S_ID). However, a given SEQ_ID can be reused after the sequence is complete.
• SEQ_ID values are not assigned in numerical order, and cannot be used to infer the order of sequences in an exchange.