What is Fibre Channel over IP (FCIP)

We already wrote about Fiber Channel, and if you remember, the default configuration for using a Fiber Channel system is to install a fiber channel card in our server and connect it to a Fiber Channel switch using fiber optic cable. All the transmission between server and the storage device goes through fiber-optic cabling.

We can, however, send fiber channel data to and from our storage devices using standard Ethernet copper wire cabling and switches. This is called Fiber Channel over IP or FCIP.  So, we connect with Ethernet cabling and Ethernet switches instead of fiber channel cabling and switches. FCIP was developed by the Internet Engineering Task Force (IETF).

Fiber Channel over IP has some great advantages over standard fiber channel. First, it is much cheaper in comparison. The downside of FCIP is the fact that it is not as fast as the standard Fiber Channel.

When we set up FCIP, we should use the fastest Ethernet hardware available, gigabit Ethernet at a minimum (gigabit NIC, gigabit switch, and CAT5e cable. Even when we use gigabit hardware, we will still not going to be quite as fast as the slowest fiber channel specification, but it’s going to cost us a lot less.

Fiber Channel Frames and Ethernet

Fiber channel frames which would be transferred on the fiber channel network, are encapsulated within the standard IP packet. This is called tunneling. Essentially, a particular fiber channel frame is put inside of an IP packet. By doing this, IP packet can transmit on our Ethernet network just like any other IP packet. Switch or any other hardware on our network don’t know that it is any different. They don’t know that inside we have a hidden fiber channel frame.

Software on both ends of the connection is configured to strip off the IP information leaving the native fiber channel frame available.

A hybrid technology called Internet Fibre Channel Protocol (iFCP) is an adaptation of FCIP that is used to move Fibre Channel data over IP networks using the iSCSI protocols. iSCSI and FCIP are typically used for different purposes. With iSCSI, SCSI commands and data frames are encapsulated in IP to support I/O disk access over an IP network. With FCIP, FC frames are encapsulated in IP so that both SCSI and non-SCSI frames can be transported over an IP network.

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