IBM 201 manual HTTP see Hypertext Transfer Protocol, IETF see Internet Engineering Task Force

higher level. In the hierarchical structure of a data station, the conceptual level of control or processing logic, above the data link level that determines the performance of data link level functions such as device control, buffer allocation, and station management.

host. (1) In TCP/IP, any system that has at least one internet address associated with it. A host with multiple network interfaces may have multiple internet addresses associated with it. The host can be (a) a client, (b) a server, or (c) both a client and a server simultaneously. (2) In Fibre Channel, any system that has at least one worldwide name associated with it. A host with multiple network interfaces may have multiple worldwide names associated with it.

host application program. An application program processed in the host computer.

host attachment. A mode of SNA communication in which the processor acts as a secondary SNA device.

host computer. (1) In a computer network, a computer that usually performs network control functions and provides end users with services such as computation and database access (T). (2) The primary or controlling computer in a multiple computer installation or network. (3) A computer used to prepare programs for use on another computer or on another data processing system; for example, a computer used to compile, link edit, or test programs to be used on another system. (4) Synonym for host processor.

hot-spare disk. A physical disk that is automatically mapped to a logical drive if one of the logical drive’s disks goes offline.

HTTP (see Hypertext Transfer Protocol).

Hypertext Transfer Protocol. In the Internet suite of protocols, the protocol that is used to transfer and display hypertext documents.

I

IBM Disk Operating System (DOS). A disk operating system based on MS-DOS that operates with all IBM-compatible personal computers.

IETF (see Internet Engineering Task Force).

iLUN. iSCSI client logical-unit number.

initial microcode load (IML). The action of loading the operational microcode.

initialize. In a LAN, to prepare the adapter (and adapter support code, if used) for use by an application program.

inoperative. The condition of a resource that has been active, but is no longer active. The resource could have failed or could have been suspended while a reactivate command was being processed.

interference. (1) The prevention of clear reception of broadcast signals. (2) The distorted portion of a received signal. (3) In optics, the interaction of two or more beams of coherent or partially coherent light.

Internet Engineering Task Force (IETF). The task force of the Internet Architecture Board (IAB) that is responsible for solving the short-term engineering needs of the Internet. The IETF consists of numerous working groups, each focused on a particular problem. Internet standards are typically developed or reviewed by individual working groups before they can become standards.

Internet Protocol (IP). A protocol that routes data through a network or interconnected networks. IP acts as an intermediary between the higher protocol layers and the physical network.

Internetwork Packet Exchange (IPX). The routing protocol used to connect Novell’s servers or any workstation or router that implements IPX with other workstations. Although similar to TCP/IP, it uses different packet formats and terminology.

interrupt level. The means of identifying the source of an interrupt, the function requested by an interrupt, or the code or feature that provides a function or service.

IOPS. Input/output operations.

IP (see Internet Protocol).

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