hesela.devFibre Channel over TCP/IP
Fibre Channel over TCP/IP (FCIP) transports encapsulated FC frames over TCP connections to join separated portions of one Fibre Channel fabric.
An FCIP link may use several TCP connections; ordering is per connection, not an unconditional guarantee across the link. [1] The common encapsulation retains the FC CRC and represents frame delimiters separately; FC frame-lifetime limits still matter across the IP path. [2]
IP protocol number 133 belongs to a pre-standard format, not standardized FCIP, which uses TCP. [4] iFCP is a different gateway protocol: its session binds an N_PORT pair to one TCP connection. [3] Its address-translation mode was deprecated; address-transparent mode was not. [4]
A transport acknowledgement is not evidence of storage-command completion or durable data. This is a protocol-layer inference, not a power-failure measurement. [1]
FC credits and TCP windows operate independently; coordination belongs to the implementation. FC Primitive Signals, Primitive Sequences and Class 1 frames are not tunneled. TCP keepalive alone does not guarantee prompt failure detection; the FC side should provide detection, and discovered TCP loss must be reported to it. [1]
When no synchronized timestamp is available, RFC 3821 requires a zero timestamp; that does not mean the frame spent zero time in transit. [1] Transit-time calculation requires a valid timestamp and aligned, synchronized time bases. [2]
Relations
- related
- Fibre Channel, Fibre Channel frame, SAN, iSCSI
Advantages
- Connects separated FC fabric portions through an IP network. [1]
Limitations
- Round-trip delay, TCP windows and buffering constrain the usable path, beyond nominal bandwidth. [1]
Citations
- RFC 3821 (July 2004): FCIP, sections 4, 5.2, 5.6, 6, 8.3.2, 8.4, 8.5 and 10.1
- RFC 3643 (December 2003): FC frame encapsulation, sections 2, 4 and 5
- RFC 4172 (September 2005): iFCP session model, section 5.2.1
- RFC 6172 (March 2011): iFCP mode deprecation and FCIP protocol number, sections 3.2 and 4
- RFC 7146 (April 2014): IPsec requirements update for storage protocols
Sources & caveats
- Foundational architecture review, not a WAN benchmark; status unknown means current commercial availability was not assessed.
- RFC 7146 updates the older security requirements. This record is not current cryptographic configuration guidance; TCP alone does not establish encryption. [5]