You wrote, "FC-IP is more of an encapsulation protocol that allows FC messages to be packaged inside of IP frames....
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Name server information is not passed between sites so the SAN islands remain separate."
Are you sure about this? I remember hearing David Black, co-chair of the IETF IPS Working Group, describe the connection between two FCIP gateways as conceptually being the connection of the E_Ports of two switches that would propagate name server information.
Editor's note: This question refers to Mr. Poelker's 2002 predictions.
iFCP is a bit more intrusive into the data flow between SAN islands. iFCP end nodes are the actual FC_N_ports within the respective fabrics. Sessions can be device specific thereby providing more granularity of control between the FC sites. iFCP is a bit more like iSCSI in implementation where the iFCP devices providing the FC to IP "gateway" (not a tunnel like FC-IP) use iSNS naming services so device-to-device communication can take place. ("In iFCP, naming is handled through a DNS/SNS entity allowing devices to be named by referencing the IP gateway and the MAC address (D_ID) behind it".) FC-IP session end nodes are the FC-IP tunnel devices themselves.
You are correct in that FC-IP does provide an "e-port" like connection between the SAN islands and that the SAN islands now become a single fabric. The difference is how FC-IP devices provide that connection. iFCP is a "GATEWAY" approach, where FC-IP is a "TUNNEL" approach. A gateway can be more intelligent than a tunnel and thus provide for implementation specific ways to provide naming services, addressing, and flow control. A tunnel just passes everything from one side to the other, and must always be up for data to flow through it. A gateway can provide for less reliable transport between devices.
Nishan systems has some great whitepapers on this topic. For the actual drafts discussing this topic go to: http://www.ietf.org/html.charters/ips-charter.html
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