iSCSI Protocol
FUNDAMENTAL ELEMENTS OF iSCSI
This section identifies the basic features of and the premises upon which iSCSI products have been designed to date. iSCSI is discussed in terms of the OSI model of computer networking. Upon completion students are able to:
- Identify the basic features of iSCSI.
- Describe iSCSI in terms of the OSI model of networking.
- Describe common design approaches to iSCSI.
- Define an iSCSI Node.
iSCSI ARCHITECTURE AND THE TCP/IP NETWORK
This section discusses the architectural design of iSCSI and the implications of transport though the TCP/IP stack is discussed and illustrated. Trace analysis is used to investigate the TCP connection creation process and the embedding of iSCSI PDUs. Upon completion students are able to:
- Identify the roles of TCP and IP.
- Identify when a new TCP connection is created.
- Define iSCSI Node, Network Entity, Session, Connection, and Target Portal Group.
- Describe an iSCSI Target Portal Group and identify how it is used.
- Describe how segmentation by other network layers affects iSCSI transmissions.
iSCSI COMMUNICATION MODEL - PROTOCOL DATA UNITS
This section introduces the iSCSI Protocol Data Unit (PDU) format, usage, and management. Upon completion students are able to:
- Describe the function of an iSCSI PDU.
- Identify the headers in an iSCSI PDU and when each is used.
- Describe the iSCSI-layer acknowledgement model.
- Describe how iSCSI orders commands.
- Identify the element with which iSCSI tracks PDUs related to a common IO or task.
iSCSI DISCOVERY
This section covers the discovery of iSCSI objects, including the use of ISNS (internet Storage Name Server). ISCSI traces are used to illustrate the discovery process. Upon completion students are able to:
- List the key information sought during discovery.
- Describe how iSCSI uses the SendTargets method of discovery to find Targets.
- Describe how iSCSI nodes register with and query the iSNS server.
CONFIGURING TARGETS: THE LOGIN PROCESS
This section discusses the Normal Login process in iSCSI. Trace analysis is used to investigate the login processes of a variety of iSCSI vendors. Upon completion students are able to:
- Identify the two types of iSCSI Login.
- Explain how the iSCSI Login relates to the TCP connection.
- Describe the two stages of the Login process.
- List the parameters which may be negotiated during Security Negotiation.
- Describe how iSCSI handles in-band authentication (CHAP) within the Login process.
- List multiple parameters which may be negotiated during Operational Negotiation.
MAPPING SCSI INTO iSCSI
This section covers the actual mapping of SCSI commands, data and status into iSCSI PDUs. Trace analysis covers various SCSI commands (Read, Write, Inquiry, etc) carried on the iSCSI transport layer. Upon completion students are able to:
- Associate SCSI commands, data & status with the appropriate iSCSI PDU.
- Chart the flow of an iSCSI transmission (IO).
- Explain under what circumstances the SCSI status phase may be collapsed into the data phase in iSCSI, including how this affects the layout of the PDU.
- Explain how Targets use R2T PDUs to flow control SCSI write operations.
- Locate embedded iSCSI PDUs in GbE frames on any protocol bit analyzer tool.
iSCSI ERROR RECOVERY AND DETECTION
This section discusses the error recovery hierarchy as outlined in the iSCSI standards. Students explore issues ranging from failed login negotiations to SCSI Check Conditions. Upon completion students are able to:
- Differentiate between the 3 main iSCSI error recovery levels, identifying the dependencies of each.
- Identify how digest errors affect iSCSI transmission flow.
- Identify how iSCSI recovers from errors that are within-command and within-connection.
- Describe how iSCSI detects and recovers from connection failure.
- Describe the effects of iSCSI Session Recovery.
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