Chapter 3. Optimizing communications performance

Many factors can affect the performance of AS/400 application programs. To achieve the best performance with your particular communications environment, you may want to review these topics:

vImproving wide area network (WAN) performance.

vImproving local area network (LAN) performance.

vImproving data path performance.

Improving wide area network performance

To achieve better performance with your AS/400 when communicating in a wide area network (WAN), you need to consider the following:

v“Adjusting WAN protocols for optimum AS/400 performance”

v“Adjusting the WAN line speed for optimum AS/400 performance”

v“WAN line speed considerations for IOPs” on page 8

Adjusting WAN protocols for optimum AS/400 performance

Wide area network (WAN) protocols affect the communications performance on AS/400. Let us use X.25 for our example. For each X.25 communications controller, the AS/400 has some processing limitation for the line, the line speed, and the total number of virtual circuits that can be used. Performance degradation can be reduced by observing these limitations.

To optimize AS/400 performance for wide area networks, perform these tasks:

vReduce the total number of frames by using larger frames.

vTo take advantage of these large frame sizes, change the MAXFRAME parameter on the line description (LIND) to reflect the maximum value. For X.25, increase the DFTPKTSIZE and MAXFRAME parameters to their maximum value.

vConfigure a WAN line as full-duplex to provide you with a higher throughput for applications that can take advantage of this mode. This can also provide higher throughput for multiple users.

vIncrease frame relay to capacity.

The data rate for a given protocol may increase as frame size increases. Under these circumstances, the central processing unit (CPU) and the input/output processor (IOP) do not do as much processing. Fewer and larger frames also make more efficient use of the communications line (higher effective data rate) because of fewer overhead bytes and line turn-arounds.

Frame relay has equivalent performance over RS449, X.21, and V.35 assuming equal line speeds and conditions. Frame relay performance (CPU time) is similar to or slightly better than Synchronous Data Link Control. For properly tuned large transfer applications, the CPU and IOP have no problem using the line speed to capacity.

For information about configuring AS/400 communications, see the Communications Configuration book.

Adjusting the WAN line speed for optimum AS/400 performance

In many cases, the communications line is the largest contributor to overall response time in the wide area network (WAN). Therefore, you should closely plan and manage its performance. In general, having the appropriate line speed is the key consideration for gaining the best performance.

To adjust the line speed for your wide area network, perform these tasks:

vCheck the difference in performance between half-duplex utilization and full-duplex utilization on the line description.

© Copyright IBM Corp. 1998, 2001

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IBM AS/400 manual Optimizing communications performance, Improving wide area network performance
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AS/400 specifications

The IBM AS/400, now known as the IBM iSeries, is a midrange computer system that has been a cornerstone of enterprise computing since its introduction in 1988. Designed to provide a robust platform for business applications, the AS/400 is celebrated for its reliability, scalability, and integrated database capabilities.

One of the key features of the AS/400 is its Integrated Operating Environment, which blends hardware and software resources seamlessly. This integration allows businesses to execute diverse workloads, ranging from traditional applications to modern web-based services, all on a single platform. The operating system, OS/400 (now IBM i), offers a rich set of APIs and tools for developers, simplifying application development and management.

Another standout characteristic of the AS/400 is its built-in database, DB2 for i. This powerful relational database management system allows for efficient data handling and provides advanced features such as support for SQL, XML, and JSON, making it easier for businesses to manage their data and integrate it with other systems. The database's tight integration with the operating system enables high performance and security.

In terms of scalability, the AS/400 can accommodate small businesses as well as large enterprises, with the ability to support hundreds of users simultaneously. Its architecture allows for easy upgrades in hardware, meaning that organizations can scale their systems without replacing the entire infrastructure.

Security is another critical attribute of the AS/400. With a sophisticated security model, it offers built-in user authentication, access control, encryption, and auditing capabilities to protect data and applications from unauthorized access.

The AS/400 also supports multiple programming languages, including RPG, COBOL, Java, and PHP, giving organizations the flexibility to choose the development tools that best fit their needs. This diversity helps maintain legacy applications while also developing new ones that leverage modern technologies.

Moreover, the platform supports both traditional green-screen interfaces and modern graphical user interfaces, allowing organizations to transition smoothly into contemporary user experience paradigms.

Overall, the IBM AS/400 stands out as a resilient, flexible, and secure computing platform that enables organizations to effectively manage their business operations, streamline processes, and adapt to changing market demands. Its unique combination of integrated features and capabilities ensures that it remains relevant in today's fast-paced technology landscape.
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