TCPIP Suite and the ARPANET Model


TCP/IP Suite and the ARPANET Model

The TCP/IP suite originally grew out of the activities of the U.S. military. The TCP/IP suite was the implementation of the four-layer networking model developed by the U.S. military and known as the ARPANET model, which predates the OSI reference model. The principal routed protocols of the TCP/IP suite include Internet Control Message Protocol (ICMP), Address Resolution Protocol (ARP), IP, TCP, and User Datagram Protocol (UDP). ICMP, ARP, and IP are specified in IETF RFCs 792, 826, and 791 respectively, and all three operate at the OSI network layer. TCP and UDP are specified in IETF RFCs 793 and 768 respectively, and both operate at the OSI transport layer. Of course, there are many routing protocols in the TCP/IP suite such as Enhanced Interior Gateway Routing Protocol (EIGRP), Open Shortest Path First (OSPF), and Border Gateway Protocol (BGP). All IP routing protocols operate at the OSI network layer.

The principal block storage protocols of the TCP/IP suite are routed protocols that operate on TCP. These include Internet SCSI (iSCSI), Fibre Channel over TCP/IP (FCIP), and Internet Fibre Channel Protocol (iFCP) defined in IETF RFCs 3720, 3821, and 4172 respectively. The iSCSI protocol enables delivery of SCSI-3 traffic by providing functionality equivalent to the OSI session, presentation, and application layers. Though iSCSI spans the top three OSI layers, many of the upper-layer protocols in the TCP/IP suite map closely to just one or two of the upper OSI layers. Examples include FCIP and iFCP, each of which map to the OSI session layer. The Common Internet File System (CIFS) and Network File System (NFS) file-level protocols discussed in Chapter 1 also run on TCP. CIFS maps to the OSI application and presentation layers and makes use of NetBIOS at the OSI session layer. NFS spans the top three OSI layers. Figure 2-5 compares the ARPANET model to the OSI reference model and lists the principal protocols of the TCP/IP suite.

Figure 2-5. ARPANET Relative to OSI





Storage Networking Protocol Fundamentals
Storage Networking Protocol Fundamentals (Vol 2)
ISBN: 1587051605
EAN: 2147483647
Year: 2007
Pages: 196
Authors: James Long

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