Patent ID: 7562137

Claim:
A method, comprising: sending a PDISC Extended Link Service frame from a first device to a second device, wherein the first device is coupled to the second device via a fabric, and wherein the PDISC Extended Link Service frame is capable of determining a presence of the second device without disrupting I/O operations between the first device and the second device; receiving the PDISC Extended Link Service frame at the second device, and determining whether an initiator with the same port address but a different World Wide Port Name (WWPN) or World Wide Node Name (WWNN) than the first device is in a logged in state to the second device; logging out the first device, and responding to the PDISC Extended Link Service frame with a LOGO frame, in response to determining that an initiator with the same port address but a different WWPN or WWNN than the first device is in a logged in state to the second device; determining, at the second device, whether the first device is considered to be logged in to the second device, in response to determining that an initiator with the same port address but a different WWPN or WWNN than the first device is not in a logged in state to the second device; accepting, by the second device, the PDISC Extended Link Service Frame, and sending an LS_ACC frame indicating that the second device considers the first device to be logged in, wherein the LS_ACC frame includes the WWNN and WWPN of the second device, in response to determining that the first device is considered to be logged in to the second device; sending, by the second device, an LS_RJT frame or a LOGO frame that includes an indication that the second device does not consider the first device to be logged in to the second device; and determining, by the first device, whether to continue the I/O operations from the first device to the second device based on receiving a response to the PDISC Extended Link Service Frame within a time period.