vFor interactive environments, keep line use below 30% to maintain predictable and consistent response times. Exceeding 50% line use usually slows down response time. The line use can be measured with the AS/400 performance tools.

vFor large transfer environments, or for environments in which only a small number of users are sharing a line, increase line use to allow for acceptable response times.

vThe CPU usage for fractional T1 support and other high-speed WAN connections is similar to any other line that runs the same type of work. As the speed of a line increases from a traditional low speed to a high-speed or full T1/E1/J1 speed, performance characteristics may change as follows:

–With interactive transactions, performance may be slightly faster.

–With a large transfer, performance may be significantly faster.

–With a single job, performance may be too serialized to use the entire bandwidth.

–With high throughput, performance is more sensitive to frame size.

–With high throughput, performance is more sensitive to application efficiency.

–With synchronous data link control (SDLC), the communications controller CPU usage increases because of polling.

Additional considerations for adjusting the wide area network line speed are the following:

vA common misconception about the line speed of each attached communications line is that central processing unit (CPU) resource is used in a uniform fashion. Exact statements cannot be made about the number of lines that any given AS/400 model can support.

vMost communications applications use a lot of CPU resource (to process data, to support disk input and output) and communications line resource (to send and receive data or display I/O). The amount of line resource that is used is proportional to the total number of bytes that are sent or received on the line.

Some additional CPU resource is used to process the communications software to support the individual sends (puts or writes) and receives (gets or reads). Communications input/output processor resource is also used to support the line activity.

vWhen a single job is running disk operations or doing non-overlapped CPU processing, the communications link is idle. If several sessions transfer concurrently, then the jobs are more interleaved and make better use of the communications link.

vPolling is an important consideration for synchronous data link control (SDLC) environments. All SDLC polling is handled by the communications controller and is governed by parameters in both the line and controller descriptions.

vFor information about AS/400 configuration, see the Communications Configuration book.

vFor more information about performance tools, see the Performance Tools for AS/400 book.

WAN line speed considerations for IOPs

When configuring a communications controller, you should consider both subsystem storage and aggregate line speed. Subsystem storage is the amount of storage available on the communications controller. Aggregate line speed is the sum of individual lines speeds that are attached to the communications controller.

The following information can help you understand network line speed considerations for input/output processors (IOPs).

vFor interactive environments, you should not exceed 60% use on the communications IOP. Exceeding this threshold in a large transfer environment or with a small number of concurrent users may still offer acceptable performance. Use the AS/400 performance tools to get the utilization.

vYou can attach multiple IOPs to an AS/400 system. The maximum number of IOPs that can be attached is determined by the AS/400 model. It is important to distribute the work load across several IOPs if the performance capabilities of a single IOP is exceeded.

vEven though an IOP can support certain configurations, a given AS/400 model may not have enough system resource (for example, CPU processing capacity) to support the work load over the lines.

vThe use of larger frames generally improves large transfer performance in terms of capacity for the communications IOP and in terms of system response time. The amount of time that the IOP spends

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IBM AS/400 manual WAN line speed considerations for IOPs
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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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