Electrical computers and digital processing systems: multicomput – Computer-to-computer data routing – Least weight routing
Reexamination Certificate
1995-10-31
2001-10-02
Donaghue, Larry D. (Department: 2154)
Electrical computers and digital processing systems: multicomput
Computer-to-computer data routing
Least weight routing
C709S226000
Reexamination Certificate
active
06298371
ABSTRACT:
BACKGROUND OF THE INVENTION
The invention relates to a method of dynamically altering the memory management procedures of the Network Control Program's (NCP's) in a Systems Network Architecture (SNA) network. For purposes of illustration, one implementation of the invention is described in connection with the well-known IBM Virtual Terminal Access Method (VTAM) software running on IBM or plug-compatible mainframe computers. It will be appreciated by those of ordinary skill having the benefit of this disclosure that the invention can be similarly implemented in other SNA-compliant networks, e.g., those involving an IBM AS/400 or similar computer. (This application is related to my commonly-assigned application Ser. No. 08/001,195, filed Jan. 7, 1993, which is incorporated by reference).
Details of the NCP program and its operational characteristics as part of the SNA protocol are extensively documented in a variety of widely available publications and other references. The IBM publications “SNA Technical Overview,” publication no. GC30-3073-3, hereafter “[SNATechOv],” and “NCP Version 5 Network Performance and Tuning,” publication no. GG24-3469, are incorporated by reference as nonessential background information familiar to those of ordinary skill. Chapters 1 and 2 and the glossary of [SNATechOv] are, potentially, especially helpful.
Appendix 1 sets out selected source code extracts from a copyrighted commercial software package distributed by the assignee of this application under the trademark OPERTUNE which manifests the invention. Permission is granted to make copies of the appendix solely in connection with the making of facsimile copies of this application in accordance with applicable law; all other rights are reserved, and all other reproduction, distribution, creation of derivative works based on the contents, public display, and public performance of the microfiche appendices or any part thereof are prohibited by the copyright laws.
1.2 Overview of SNA Architecture & Glossary of Terms
The concepts discussed in the overview explanation that follow are illustrated in
FIG. 1
, which is a block diagram showing the hierarchical nature of the SNA architecture.
SNA was developed as a hierarchical architecture organized into groups that have specific functions. SNA “nodes” are collected into a structure of “networks,” “domains,” and “subareas” as explained in the following glossary of selected terms well known to those of ordinary skill:
37xx: the product number of a series of communication controllers introduced by IBM between 1975 and the present. The 37xx series controllers execute a software program called Network Control Program (NCP) that controls and directs communication controller activity. These controllers are responsible for relieving the central processing unit of much of the burden of communications management.
Boundary link: a link comprising part of a path between two SNA nodes and physically terminating in or attached to one of the nodes. See also Intermediate link.
Channel: an SNA channel (sometimes referred to as a “370 data channel”) is a communications path, largely local to a host computer and its on-site peripherals, that makes use of a specific SNA communications protocol. See [SNATechOv], FIGS. 1-3. Channels are sometimes referred to colloquially as “channel attachments” attached to a host computer. The protocol used in channel attachments is characterized by comparatively high data throughput, e.g., 3 million bytes per second (Mbps) and higher.
Controller: a communication's controller (sometimes referred to as a “cluster controller”) provides an interface between an SNA network and one or more end users at terminals to the SNA network. It buffers the entries that users make at their terminals. When polled by the NCP, the cluster controller delivers the buffers to the NCP. When the NCP selects and delivers messages to the cluster controller, the cluster controller receives the buffers and delivers each message to the correct terminal.
Domain: all subareas that are controlled by a common VTAM (P
5
) node.
FEP: Front End Processor, a name given to the 37xx series and compatible communication controllers.
Intermediate link: a link comprising an intermediate part of a path between two SNA nodes but not physically terminating in or attached to either node. See also Boundary link.
Load module: a module of executable program code and preallocated/preformatted memory loaded into NCP processor memory during NCP initialization. The load module provides the data storage and manipulation routines necessary for NCP execution.
Link: a communications path between two nodes in a SNA network, normally operating in conformance with the Synchronous Data Link Control (SDLC) communications protocol.
LU: logical unit.
NCP: see Network Control Program.
Network: all connected domains.
Network architecture: the rules that govern the services, functions, and protocols of network components. A widely used network architecture is the Systems Network Architecture (SNA) developed by IBM.
Network Control Program (NCP): an IBM computer program that executes in the communication controller's hardware to perform the work of network communication for remote connections. The NCP polls the cluster controllers to send and receive messages and controls dialing and answering modems that are attached to it. The NCP routes messages that are destined for other subareas.
Network resource: the speed or capacity of a physical network component that is needed by network users to move data from one point to another in a network.
Network user: an end user or application that requires network resources to complete assigned tasks.
Node: a set of hardware, and the software associated with that hardware, that implements all seven standard layers of the SNA architecture (which are physical control, data link control, path control, transmission control, data flow control, presentation services, and transaction services).
Overutilization: a network problem that occurs when the number of network users exceeds the capacity of a network resource. Network users must either accept less of the resource than they requested, or wait longer to acquire the requested amount. See also Underutilization.
P
2
: a designation for a cluster controller.
P
4
: a designation for an NCP node.
P
5
: a designation for a VTAM node.
Path information unit: a unit of message traffic.
PIU: path information unit.
PU: physical unit.
SDLC: Synchronous Data Link Control.
Session: a connection between two logical units (e.g., two applications or an application and an end user) that establishes the rules and a path for communication between the two. All sessions are initiated through a host processor executing VTAM. Two logical units that are connected in this way are often referred to as being “in session.”
SNA: Systems Network Architecture.
Subarea: a VTAM or NCP node (P
5
or P
4
) and all the cluster controllers (P
2
s) or token rings that are attached and controlled by it.
Underutilization: a network problem that occurs when much of the capacity of a network resource is not needed by network users and is being wasted. See also Overutilization.)
DOS/VSE: Disk Operating System/Virtual Storage Extended. A mainframe operating systems developed by IBM that is an extension of an earlier operating system, Disk Operating System/Virtual Storage (DOS/VS).
VTAM: Virtual Telecommunications Access Method software. VTAM executing in a host processor system controls the interface between host applications and the network. It also maintains the domain configuration and initiates communications called “sessions” between the other network components. A newer type of SNA component can initiate sessions between two PU nodes without VTAM; a process known as Advanced Peer-to-Peer Networking or “APPN.”)
1.3 Initialization of a SNA Network
A key aspect of the background of the invention is the manner in which initialization of a SNA network is normally accomplished. As is well known to those of ordinary sk
BMC Software Inc.
Donaghue Larry D.
Howrey Simon Arnold & White , LLP
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