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Link Services Architecture Reference Model

IP.com Disclosure Number: IPCOM000122658D
Original Publication Date: 1991-Dec-01
Included in the Prior Art Database: 2005-Apr-04
Document File: 5 page(s) / 188K

Publishing Venue

IBM

Related People

Horton, VG: AUTHOR [+6]

Abstract

The Link Services Architecture (LSA) Reference Model provides a single, consistent framework to support the concepts, terminologies, and structure needed for communications functions which exist in a variety of upper level communication systems. The model allows service definitions which are independent of the system facilities of the product implementing the communications services.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 39% of the total text.

Link Services Architecture Reference Model

      The Link Services Architecture (LSA) Reference Model
provides a single, consistent framework to support the concepts,
terminologies, and structure needed for communications functions
which exist in a variety of upper level communication systems.  The
model allows service definitions which are independent of the system
facilities of the product implementing the communications services.

      In today's world of differing communications environments, it
is desirable to achieve a common Data Link appearance to allow using
and managing upper level communications resources to have a common
configuration, operation, management and problem analysis across all
types of link connections.  The LSA reference model is defined to
serve as a framework for services and protocols, providing a
well-defined lower- layer system structure for systems incorporating
existing and evolving communications standards.

      The LSA reference model is an abstract model of a real open
system.  As a conceptual and functional framework, its goal is to
define a common basis for coordinated development.  The LSA reference
model consists of the functional entities and external resources
depicted in the figure.

      Functions that must be performed by upper level software are
identified as external resources.  These functions are depicted in
the figure by the CNM, CONNECTION, ERROR LOG, XID Managers the ENTITY
ENABLER and the DATA USER.  These external resources are needed to
define where LSA sends asynchronous primitives.  For example, when an
unsolicited XID is received, LSA must know to route the XID to the
XID manager for validation.

      All of the external resources may not be required by every
protocol.  The LSA reference model identifies a superset of external
functional resources and each protocol identifies the resources that
it requires.
CNM Manager

      This manager provides communication network management (CNM)
functions to LSA.
Connection Manager

      This manager performs the required connection procedures using
the primitives defined and supported by LSA.
XID Manager

      The exchange identification (XID) manager uses LSA primitives
to send and receive XID commands.  This XID exchange is performed for
node identification and role negotiation.
Error Log Manager

      The error log manager receives indications of protocol or LSA
entity errors.
Entity Enabler

      The entity enabler component provides the initial configuration
parameters to a newly created entity.  The entity enabler also clears
the configuration when desired.
Data User

      The data user uses LSA primitives to send and receive protocol
data units (PDUs) and to control the data flow between the user and
the protocol entity.
LSA Entities

      LSA defines the following functional entities: 1) port
connection manager; 2) short hold manager; 3) SNA X.25 logical link
control;...