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Communications "Port Manager" for Computer Systems

IP.com Disclosure Number: IPCOM000035730D
Original Publication Date: 1989-Aug-01
Included in the Prior Art Database: 2005-Jan-28
Document File: 5 page(s) / 45K

Publishing Venue

IBM

Related People

Labriola, MH: AUTHOR [+2]

Abstract

A technique is described whereby a structured software implementation, called "Port Manager" (PM), provides an efficient means of managing input/output (I/O) communication ports in the supervision of a variety of tasks. The structured supervisor PM enables many different kinds of hardware I/O ports to be shared by many different communications protocols by identifying a structure of functions for computers interacting with each other, as used in real-time multi-tasking computer networks. The PM concept can be applied from the simplest form of supervising computer to printer, or terminal, to the supervision of multilayer data link controls.

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Communications "Port Manager" for Computer Systems

A technique is described whereby a structured software implementation, called "Port Manager" (PM), provides an efficient means of managing input/output (I/O) communication ports in the supervision of a variety of tasks. The structured supervisor PM enables many different kinds of hardware I/O ports to be shared by many different communications protocols by identifying a structure of functions for computers interacting with each other, as used in real- time multi-tasking computer networks. The PM concept can be applied from the simplest form of supervising computer to printer, or terminal, to the supervision of multilayer data link controls.

In layered communications, as defined by the International Standards Organization, the PM is designed to supervise all physical layer, port-related activity. Although not part of the physical layer of any one data link control (DLC) task, it provides support to all active tasks present in a system. Among a variety of functions, the PM may be used to activate a leased line, set up a switched connection or supervise the sharing of physical I/O ports, among a number of active DLC tasks. Although the PM removes most of the hardware dependency from the DLC and its physical layer, some hardware functions remain in the physical layer of each DLC.

The PM is essentially a task which supervises tasks that run under its control, as shown in Fig. 1. As new interfaces are added, the software to support the interface can be configured below the PM. As more links are added, the DLC and physical layer support for the link will use the PM to provide the necessary link service.

(Image Omitted)

Typically, communications I/O is supported in layer form. A communications link is supported by the DLC protocol software and its associated physical layer. One link, such as point-to-point or multi-dropped, is supported by one instance of physical layer code which performs all interface related functions. As a result, the physical layer code is defined for a fixed type of interface, as shown in Fig. 2. Through the use of the PM, the physical layer code is allowed to be independent of interface type. Once the interface is initialized, the data transfer mechanism for most of the interfaces are then similar. It is at this point that the port is returned to the requesting physical layer.

In most systems, port supervision is placed on the same level as link supervision. Links are usually configured to be associated with a predefined port. If a port/link configuration is changed, it must be done at higher layers. Sharing of ports between active links is therefore a cumbersome and time- consuming processes. However, by using the PM concept, higher layers are allowed to be freed of this responsibility. Port groupings can be configured and can be shared between links when these ports are connected to a switched network. This feature is especially useful for X.21 interfaces. A smal...