Difference Between iFCP and FCIP
Fibre Channel (FC) is the most widely used technology for storage networking. Data networking world is ruled by TCP/IP. FC and TCP/IP are two different worlds. Is there a way to send storage data across the omnipresent TCP/IP without losing the FC advantage? Is a connection between the two domains possible? The answer is yes, by using Internet Fibre Channel Protocol (iFCP) & Fibre Channel over Internet Protocol (FCIP). The Storage Networking Industry Association (SNIA) has standardized these protocols, but haziness exists on differences between the two and the suitability of each in the enterprise scenario. This paper aims to resolve the nebulosity.
How does iFCP work?
iFCP is a gateway to gateway protocol that is used to connect FC devices and/or FC SANs to existing IP infrastructure. As shown in Fig 1, individual FC devices can communicate via the IP network using iFCP gateways. The gateways talk using iFCP. FC messaging services and routing services are terminated at the gateways so the fabrics are not merged to one another.
iFCP has been designed to use the existing TCP/IP network’s transport services. It sends FC data on the transport connections provided by TCP. Thus the fabric services are provided by TCP/IP and not by FC. As can be seen from Fig. 2, the only the Top layer of FC-4 is utilized in the stack, the lower layers are TCP/IP layers. Thus the FC4 layer which is the upper level layer sends storage data it receives from applications, using the TCP transport services.
How does FCIP work?
FCIP is a protocol used for connecting geographically separated FC SAN’s. It does so by tunneling through the IP network to connect the FC SANs. Tunneling refers to the concept of transporting encapsulated FC frames across an IP network. Encapsulation means that the payload of the Ethernet frames carry FC frames. The fabric services are those of the individual FC SAN in this case.
Both the protocols are methods to connect the two worlds of FC and TCP/IP. They have their relative merits and areas of applications. They seem to be competing technologies and their application areas look similar. The key to choosing between them is to understand your requirements well. FCIP is useful in places with a low budget. It is so because the existing infrastructure does not need to be altered. Merely a FC to IP gateway needs to be installed. iFCP on the other hand is a costlier alternative as it requires an iFCP gateway for each device but with the advantage that each device to device connection, can utilize a different transport level service.