FIBRE CHANNEL and IP SAN INTEGRATION(8)

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

scenarios of overload and congestion that can result in performance and stability issues that impact the entire fabric. For a medium to large fabric, these are critical issues for concern. Most FCIP deployments are based on small fabrics, where there are a small number of devices and switches at each end of the FCIP link, and these issues are less critical.3.4 iFCPiFCP technology is a gateway-to-gateway protocol for providing FC device-to-FC device communication over TCP/IP. For each pair of FC devices, there is an iFCP session created between a pair of gateways supporting the devices. An iFCP session uses a TCP connection for transport and IPSec for security, and manages FC frame transport, data integrity, address translation, and session management for a pair of FC devices. Since an iFCP gateway handles the communications between a pair of FC devices, it only transports device-to-device frames over the session, and, hence, the FC fabrics across the session are fully isolated and independent. This is a major difference between iFCP and FCIP, in that FCIP builds an extended fabric, tunneled over IP. In contrast to an FC-iSCSI gateway, an iFCP gateway transports FC device-to-device frames over TCP, and in most cases original FC frames, including the original CRC and frame delimiters, are transported. An FC-iSCSI gateway terminates and translates SCSIFCP protocol from the FC side and similarly terminates and translates iSCSI protocol from the IP side. SERVER FC-4FCiFCP GWiFCP sessionsFCiFCP GWSTORAGEFCIPFC FC-4SERVERSTORAGE Figure 4 FC-iFCP GatewayThe iFCP draft standard specifies an address-translation mode as well as an addresstransparent mode, depending on whether the FC addresses of devices are translated or not. An FC device exchanges login and protocol parameters with another FC device using FC link service protocol frames as part of the session creation and parameter exchange protocol. In address-translation mode, a gateway intercepts these device-to-device link service protocol frames and translates device addresses embedded in the frames. It regenerates frame CRCs when the original frame content is changed, which imposes extra overhead on the iFCP gateway. Address translation is a particularly useful feature when interconnecting FC fabrics. It enables installation of a gateway between existing108