Seagate Fibre Channel Interface - Manual (Page 104)

90 Fibre Channel Interface Manual, Rev. D
9.2.9 Port Discovery (PDISC)
Port Discovery (PDISC) is sent by an initiator to a drive after loop initialization to verify addresses have not
changed. The PDISC transfers the same information as the PLOGI except that the LS Command code in the
first word of the payload is 50000000h. The PDISC does not cause the open exchanges (commands) to be dis-
carded if the initiator address and parameters have not changed. For other contents of the payload, see Sec-
tion 9.2.1, Port Login (PLOGI).
The accept for the PDISC is the same as for the PLOGI if the drive detects the initiator AL_PA (Physical
Address) or parameters have not changed from a previous login. Section 9.2.1, Port Login (PLOGI). If the drive
detects either the initiator addresses or parameters have changed from a previous login, the drive will not send
an accept. The drive will return a LOGO to indicate to the initiator a PLOGI is required.