FIBRE CHANNEL and IP SAN INTEGRATION(6)

The maturity and mission-critical deployment of Fibre Channel (FC) in storage area networks (SANs) creates a unique class of multi-terabit networks with demanding throughput, latency, scalability, robustness, and availability requirements. This paper revie

3.2 iSCSIiSCSI is a SCSI over TCP transport protocol used between a SCSI initiator and a SCSI target for storage-block level transport of SCSI commands and payloads. iSCSI protocol uses TCP/IP and IPSec as its network transport and security protocols. It has many features designed to leverage standard TCP/IP protocols to block storage needs. These features include the use of multiple TCP connections (for a given session), cyclic redundancy check (CRC) digests, out of order data placement, and TCP connection failure recovery options. iSCSI design and analysis have been presented in several papers [12, 13, 14, 15, 16]. STORAGE SERVER FC-4 FC FCiSCSI GW ISCSI IP iSCSI STORAGE STORAGE Figure 2 FC-iSCSI Gateway In Figure 2, the FC-iSCSI gateway provides the internetworking of iSCSI devices with FC devices, while communicating with each of the networks appropriately. While the FC SAN and the IP SAN are operating independently, the gateway maps selected iSCSI devices into the FC SAN and selected FC devices into the IP SAN. When a FC server creates a SCSI-FCP session to a storage device, the gateway intercepts the request and acts as a proxy for the storage device. On the IP side, the gateway acts as a proxy initiator (for the server), and creates an iSCSI session for the storage device. The gateway maintains and manages the state of the gateway portion of supported sessions. For an IPbased server creating an iSCSI session to a FC storage device, the gateway performs similar roles as proxy target on iSCSI session and proxy initiator for the SCSI-FCP session. An iSCSI gateway performs several important functions, including FCP and iSCSI session-level protocol translations, command and payload forwarding, error checking, and command/session-level error propagation. A gateway has to manage device discovery and registry (on the IP side with an iSNS server, and on the FC side with FC name services), authentication of FC and IP devices, and mapping of device names to local addresses, etc. It is important that a gateway is as transparent as possible to the servers and storage devices using the gateway, while maintaining high data integrity. It106