Executive Summary

This White Paper provides a conceptual overview of iSCSI emphasizing the relationship of the iSCSI protocol to other computer subsystems. A basic understanding of mass storage and networking technologies is assumed. Concepts presented in this document include:

•iSCSI relationship with SCSI and TCP/IP

•iSCSI co-existence with current network traffic

•iSCSI utilization of mass storage and networking concepts

•iSCSI definition in terms of current network model

•iSCSI definition in terms of current mass storage model

1.Introduction

The Internet Small Computer Systems Interface (iSCSI) is a SCSI mass storage transport that operates between the Transport Control Protocol (TCP) and the SCSI Protocol Layers. The iSCSI protocol is defined in RFC 3720 [iSCSI], which was finalized by the Internet Engineering Task Force (IETF) in April, 2004. A mandate of the iSCSI protocol design required no modifications to the existing SCSI or TCP/IP protocols.

Figure 1. SCSI Transport Protocols

Applications

File Systems

Volume Management

SCSI Protocol Layer

Parallel SCSI	FCP and	iSCSI
Transport	Fibre Channel	Transport
	Transport

Networking

Upper

Level

Protocols

TCP

Ethernet

The Small Computer Systems Interface (SCSI) Architectural Model [SAM] is a family of protocols defining a communication protocol with SCSI I/O devices. SCSI is a client-server architecture. The phrase “SCSI Client” is synonymous with “SCSI initiator” and “SCSI server” is synonymous with