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USE OF THE FICON ESTABLISH LOGICAL PATH FUNCTION TO INITIALIZE OPERATING FICON PARAMETERS

IP.com Disclosure Number: IPCOM000014305D
Original Publication Date: 2002-Mar-21
Included in the Prior Art Database: 2003-Jun-19
Document File: 2 page(s) / 28K

Publishing Venue

IBM

Abstract

This disclosure describes a method for a FICON (FC-SB-2) channel to discover the operating parameters which a control unit supports, and to set the mode of operation to use those parameters for all communication between the channel and that control unit. A method of discovering operating parameters is needed because initial releases of FICON used a default set of operating parameters. As enhanced modes of operation developed and were supported by control units and channels, a channel needed the ability to discover the set of parameters supported by a given control unit so that it could use the enhanced parameters when communicating with that control unit. Without this capability, there would be no mechanism to accommodate newly developed functions into the FICON definition without causing incompatibilities with existing products or forcing design changes.

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  USE OF THE FICON ESTABLISH LOGICAL PATH FUNCTION TO INITIALIZE OPERATING FICON PARAMETERS

    This disclosure describes a method for a FICON (FC-SB-2) channel to discover
the operating parameters which a control unit supports, and to set the mode of
operation to use those parameters for all communication between the channel and
that control unit. A method of discovering operating parameters is needed because
initial releases of FICON used a default set of operating parameters. As enhanced
modes of operation developed and were supported by control units and channels, a
channel needed the ability to discover the set of parameters supported by a given
control unit so that it could use the enhanced parameters when communicating with
that control unit. Without this capability, there would be no mechanism to
accommodate newly developed functions into the FICON definition without causing
incompatibilities with existing products or forcing design changes.

In order to discover the set of operating parameters, this scheme expands
the usage of the FC-SB-2 Establish Logical Path (ELP) function to (a)
discover the set of enhanced operating parameters common to a channel and a
control unit, and (b) set the mode of operation to use those features. To
accomplish this, a "supported optional feature vector" is included in the
ELP request. Each bit of this vector corresponds to an optional feature.
The bit for the optional feature is set to one if the optional feature is
supported; otherwise the bit is set to zero. Examples of optional features
which may be supported are: increased IU size (8K vs.16K vs. 32K), variable
link timeout values (500 microseconds vs. 1 millisec vs. 3 millisec), etc.

When a control unit...