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Reason Code for Logical Path Removed

IP.com Disclosure Number: IPCOM000120023D
Original Publication Date: 1991-Mar-01
Included in the Prior Art Database: 2005-Apr-02
Document File: 2 page(s) / 81K

Publishing Venue

IBM

Related People

Sachs, MW: AUTHOR

Abstract

Dynamic creation of logical paths between channels and control units in an I/O system is an essential component of automated configuration management because it allows communication associations between channels and control units to be created without the customer having to manually enter the addresses of the channels into the control units.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 52% of the total text.

Reason Code for Logical Path Removed

      Dynamic creation of logical paths between channels and
control units in an I/O system is an essential component of automated
configuration management because it allows communication associations
between channels and control units to be created without the customer
having to manually enter the addresses of the channels into the
control units.

      In such a system, a logical path is created when a channel
issues a specific link control message, which might be called
Establish Logical Path (ELP), to a control unit. The ELP message may
also contain information which controls subsequent operations on the
logical path, such as values of parameters of the data flow control
algorithm.  If the control unit is able to accept the logical path,
it responds with a message which might be called Logical Path
Established (LPE).  If it is unable to accept the logical path, it
refuses by responding with a message which we call Logical Path
Removed (LPR).

      There are several reasons why a control unit might refuse a
logical path.  Some reasons are listed below.  If the control unit
can indicate why it refused the logical path, the recovery action for
refusal of a logical path can be based on the reason why the logical
path was refused. Without an indication of why the logical path is
being refused, the value of dynamic creation of logical paths is
severely limited because it is not possible to take intelligent
corrective action.

      It is particularly important to be able to determine why a
logical path was refused when the system provides physical
connectivity from channels to a particular control unit which may
considerably exceed the resources in that control unit for
establishing logical paths.  This makes it essential to be able to
determine whether the control unit refused the logical path because
of resource limitations or because of a configuration error.

      This invention provides a means of indicating why the logical
path was refused.  In this...