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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: iSCSI : Login Phase ProblemsSantosh, That is already in in 04 as I was refining the security negotiation. Regards, Julo Santosh Rao <santoshr@cup.hp.com> on 24/01/2001 09:18:30 Please respond to Santosh Rao <santoshr@cup.hp.com> To: ips@ece.cmu.edu (ips) cc: santoshr@hpcuhe.cup.hp.com (Santosh Rao) Subject: iSCSI : Login Phase Problems Julian & All, Problem : ========= The login phase is intended to be driven by the initiator and it is the one to decide if only a Login PDU is sufficient or it needs a Login + Text PDU. The initiator needs a mechanism to indicate to the target that a Text command will [or will not] follow the login command. However, by placing the "F" bit in the login response and NOT the login command, the iSCSI login phase opens up a number of questions : Reference ======== Section 4, 4.1 of rev 03 iSCSI draft. The login phase is negotiated as follows : =========================================== Initiator Target =========================================== 1) Login -----------> <---------- 1) Login response of "accept login" with F=0 2) Text ------------> <----------- 2) Text Response : : <------------ 3) Login Response of "accept login" with F=1 Issues : ======== 1) Without a communication from the initiator on whether it intends to follow the login command with a text command, the target may send back a login accept with the "final" (F) bit set, when the initiator was still interested in negotiating more keys. 2) The target may send back an interim login accept ("F" bit is not set), expecting the initiator to continue negotiation with a text command. The initiator may have no further keys to negotiate and so, does nothing. When is the login phase then deemed to be complete ? (i.e. what causes the tgt to do a final login accept (F bit set)). 3) If multiple Text commands are to be allowed in the login phase, how does a target know that the initiator is done with all its key negotiations and has sent all its text commands ? If multiple Text commands are NOT allowed in the login phase, then, the draft MUST state this explicitly. It is the initiator that drives the Login/Text negotiations and hence, it is the initiator that must decide whether a login is sufficient or a login will be followed by a text phase. Therefore, the "F" bit currently in the login response should actually be in login command. The initiator is the master of the login phase and it should drive the login + text phases. Solution : ========== Case I (only login command used ) --------------------------------- Initiator Target ====================================== Login(F bit set) ------> <----- Login Accept (F bit set) Case (II) (login + text commands used in login phase) ----------------------------------------------------- Initiator Target ====================================== Login(F bit NOT set) ------> <----- Login Accept (F bit NOT set) Text (F bit NOT set) ------> <----- Text Response : : Text (F bit set) -----> <---- Text Response <---- Login Response (F bit set) Comments ? Regards, Santosh -- ################################# Santosh Rao Software Design Engineer, HP, Cupertino. email : santoshr@cup.hp.com Phone : 408-447-3751 #################################
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