1. Field of the Invention
This invention generally relates to transporting timer protocols over a network using the Generic Frame Procedure. More specifically, the invention relates to an architecture and a procedure well suited to enable the transport of Sysplex Timer protocols over Generic Frame Procedure networks.
2. Background Art
Over the past several years and continuing to the present, computer manufacturers are providing processing architectures based on a multi-system shared data approach. Through these architectures, multiple large-scale computer systems, each of which is often referred to as a computer processing complex (CPC) or a central electronic complex (CEC), are interconnected, through, for example, a coupling facility or other inter-processor communication mechanism, to permit each such system to gain read-write access to data residing on one or more shared input/output devices, such as a direct access storage device (DASD). The resulting inter-connected computer system is commonly referred to as a “sysplex”. In a sysplex, as with a typical multi-processing environment, a processing workload is generally distributed among all of the inter-connected computer systems such that each computer system is responsible for processing a portion of the entire workload. Owing to the inherent high reliability and highly cost-efficient expansion potential of a sysplex architecture, sysplexes are particularly attractive in handling so-called critical business support applications that involve real-time transaction processing and can tolerate essentially no downtime.
Certain currently available machines that can be readily incorporated into a sysplex, such as illustratively the Enterprise System/9000 (ES/9000) Series manufactured by the International Business Machines (IBM) Corporation, can each support, if appropriately configured, multiple actively and simultaneously executing copies of various operating systems (OS) to implement separate corresponding individual and unique application processing environments. (Enterprise System/9000 is a registered trademark, and ES/9000 is a trademark, of IBM Corporation)
Sysplexes, and other networks, may employ various technologies for transmitting data within the sysplex or network. For example, one technology, which has been in use for some time in telecommunication networks, but has only begun to find emerging applications in sysplex communications is referred to as SONET/SDH. SONET/SDH, which is an acronym for Synchronous Optical Network/Synchronous Digital Hierarchy, is a set of related standards for synchronous data transmission over fiber optic networks. SONET/SDH is currently used in wide area networks (WAN) and metropolitan area networks (MAN). A SONET system is comprised of switches, multiplexers, and repeaters, all connected by fiber. The connection between a source and destination is called a path.
More recently, the International Telecommunications Union (ITU) has proposed a new industry standard G.704.1 called Generic Frame Procedure (GFP). This is intended to allow standard datacom protocols such as ESCON or FICON to be encapsulated into a SONET/SDH compliant frame structure, so they can be transported across installed SONET networks. Since there is a large amount of SONET infrastructure installed by telecom carriers and other service providers, GFP is seen as the means for allowing enterprise systems to carry data traffic over existing SONET networks at very low incremental cost. In turn, this enables channel extensions over hundreds of kilometers for disaster recovery applications, such as large storage area networks. In order to remain competitive in the telecom carrier market, many wavelength division multiplexing (WDM) equipment manufacturers are adopting GFP transport.
Many networks, however, are not fully compatible with GFP. For example, in a Sysplex, timing data, referred to as Sysplex Timer links, cannot be readily transported over GFP at the present time.