HP-UX iSCSI Software Initiator Support Guide, HP-UX 11i v1 and 11i v2, July 2005

Chapter 1

iSCSI Overview

iSCSI Login

The iSCSI Login Phase consists of Login requests and responses. Once authentication has occurred and

operational parameters have been set, the session transitions to the Full Feature Phase and the initiator

begins performing SCSI I/Os. NOTE: Using authentication is optional.

iSCSI parameters are negotiated using Login Requests and Responses, during session establishment. During

the Full Feature Phase, iSCSI parameters are negotiated using Text Requests and Responses. In both cases

the mechanism is an exchange of iSCSI-text-key=value pairs (also referred to as key=value pairs).

The Login Phase proceeds in two stages:

• Security/Authentication Stage

This stage consists of text exchanges using IDs, Certificates, etc., using key=value pairs.

One of the keys that is negotiated in this stage of the Login Phase is AuthMethod. For example:

key=value AuthMethod=CHAP

AuthMethod defines the authentication method.

• Operational Parameters Negotiation Stage

This stage consists of text string negotiation of operating parameters using key=value pairs of login

parameter exchanges.

Two of the many login keys that are negotiated in the Operational Parameters Negotiation stage of the

key=value MaxRecvDataSegmentLength=<numerical-value>

MaxRecvDataSegmentLength defines the maximum data segment length an initiator or target can

receive in an iSCSI PDU (in bytes).

key=value FirstBurstLength=<numerical-value>

FirstBurstLength defines the maximum amount of unsolicited data the initiator can send to the

target during the execution of a single SCSI command (in bytes).

NOTE For a complete list of iSCSI login keys, consult RFC 3720 at:

http://www.ietf.org/rfc/rfc3720.txt

iSCSI Full Feature Phase

After successfully completing the Login Phase on the first (leading) connection of the session, a session is in

Full Feature Phase.

In the Full Feature Phase, the initiator sends SCSI commands and data to the target by encapsulating them

in iSCSI PDUs that go over the iSCSI session (transport). The initiator receives SCSI responses embedded in

iSCSI PDUs, from the target. SCSI I/O only occurs after the Full Feature Phase begins.